This PDF file contains the front matter associated with SPIE Proceedings Volume 10021, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

Wavelength Raman converters have been developed for years to provide an elegant solution to easily shift the wavelength of existing lasers. In the pulse regime, due to relatively low Raman gains, these converters are usually limited to high-energy pulses, typically a few J or a few mJ in the nanosecond or picosecond regime. In order to build efficient Raman converters with lower energy pulses, we have developed a new class of fiber wavelength shifters based on Stimulated Raman Scattering in the liquid filling the hollow core of photonic bandgap fibers or Kagome fibers. The liquid choice, the design of the photonic crystal microstructure, the fiber length and its diameter give us enough degrees of freedom to realize efficient and versatile shifters, each being optimized for a specific wavelength shift. Connecting such a fiber device to a fixed wavelength laser allows delivering a new wavelength. With the same laser, another wavelength can be obtained by connecting another shifter. Using microlasers delivering 532 nm sub-nanosecond pulses of about 1 μJ, we already built a full series of shifters to reach any wavelength among: 556 nm; 561 nm; 582 nm; 595 nm; 612 nm; 630 nm; 650 nm; 667 nm; 772 nm. Hereafter, we detail how we design and optimize these new devices.

We present diffractive optical elements (DOEs) for generating wavelength-multiplexing and three-dimensional (multi-dimensional) arrays of spots that are smaller than the single diffraction limit spot. Such small spots are referred to as subdiffraction-limit spots. This method is based on the use of propagating light, and its superior features, including spatial parallelism and remote accessibility to matter, can be utilized in applications. In design, special constraints are introduced into the Gerchberg-Saxton algorithm to control the phases of spots and to disperse light energy to a surrounding area. In each iteration, the phase distribution of a wavelength- multiplexing DOE is synthesized from the phase distributions obtained tentatively for the individual wavelengths. As an example, a two-wavelength two-plane DOE was investigated. The design result showed that expected spot arrays were generated for two wavelengths on the individual output planes. We constructed an experimental system with a spatial light modulator and demonstrated that the generated spot arrays were in conformity with the design result. Spot sizes were reduced to about 80% of that of the diffraction limit spot. Characteristics of this type of DOEs were also evaluated by numerical calculation. For example, the result shows that the depth of focus is extended in subdiffraction-limit spot generation. We believe that this study contributes to expand application fields of DOEs.

The improvement of the optical devices in this decade, such as the MEMS-SLM ( Micro Electro Mechanical Systems- Spatial Light Modulator ) and wave front sensor with micro lens device, is making adaptive optics commonly available. It also gives the new basis of the design of adaptive optics with the improved accuracy and the compactness. We have developed an adaptive optics bench from such a point of view, and the application to the optical microscope has attained effective results in the observation of the live cell samples. In this presentation, our recent results will be shown. The result includes analysis of blur by the fine structures in biological sample and result of the image correction by the adaptive optics.

Chromostereopsis can be sight and feel in “Virtual Reality” adapters, that induces the appearance of color dependant depth sense and, finally, combines this sense with the source conceived depth scenario. Present studies are devoted to investigation the induced chromastereopsis when using adapted “Virtual Reality” frame together with mobile devices as smartphones. We did observation of composite visual stimuli presented on the high spatial resolution screen of the mobile phone placed inside a portable “Virtual Reality” adapter. Separated for the left and right eyes stimuli consisted of two areas: a) identical for both eyes color chromostereopsis part, and b) additional conventional color neutral random-dot stereopsis part with a stereodisparity based on the horizontal shift of a random-dot segment in images for the left and right eyes, correspondingly. The observer task was to equalize the depth sense for neutral and colored stimuli areas. Such scheme allows to determine actual observed chromostereopsis disparity value versus eye stimuli color difference. At standard observation conditions for adapter with +2D ocular lenses for mobile red-blue stimuli, the perceptual chromostereopsis depth sensitivity on color difference was linearly approximated with a slope S_ChS ≈ 2.1[arcmin/(Labcolor difference)] for red-blue pairs. Additional to standard application in adapter the tuneable “Varioptic” liquid lens oculars were incorporated, that allowed stimuli eye magnification, vergence and disparity values control electrically.

Aberration vignetting phenomena changes light distribution in the image plane. A method of physically accurate simulation of this effect in optical devices is presented. We modified a stochastic ray tracing technique to use it for the analysis and visualization of the aberration vignetting. Some useful illustrations with a number of visual examples of these phenomena for different optical systems are given: bi-concentric lens, wide-angle lens, fish-eye lenses, etc.

In this paper, we report on comparisons of single-pixel imagings using Hadamard Transform (HT) and the ghost imaging (GI) in the view point of the visibility under weak light conditions. For comparing the two methods, we have discussed about qualities of images based on experimental results and numerical analysis. To detect images by the TH method, we have illuminated the Hadamard-pattern mask and calculated by orthogonal transform. On the other hand, the GH method can detect images by illuminating random patterns and a correlation measurement. For comparing two methods under weak light intensity, we have controlled illuminated intensities of a DMD projector about 0.1 in signal-to-noise ratio. Though a process speed of the HT image was faster then an image via the GI, the GI method has an advantage of detection under weak light condition. An essential difference between the HT and the GI method is discussed about reconstruction process. Finally, we also show a typical application of the single-pixel imaging such as hyperspectral images by using dual-optical frequency combs. An optical setup consists of two fiber lasers, spatial light modulated for generating patten illumination, and a single pixel detector. We are successful to detect hyperspectrul images in a range from 1545 to 1555 nm at 0.01nm resolution.

Geometrical waveguide has obvious advantage over other see-through technologies to achieve high resolution, ultra-thin thickness, light weight and full-color display. The general principle of waveguide display is introduced and the key challenges involved with geometrical waveguide display and the way to conquer them is discussed. Ultra-thin geometrical waveguide for see-through HMDs with different properties is reviewed in this paper, including waveguide with partially-reflective mirrors array (PRMA), trapezoidal microstructures and triangular microstructures. Finally, a type of ultra-thin waveguide display which can be fabricated with the technology of injection molding is presented, and the thickness can be reduced to less than 2mm with an EPD of 12mm and a FOV of 36°.

Design and analysis of an optical system is often a multidisciplinary task, and can involve the use of specialized software packages for imaging, mechanics, and illumination. This paper will present a case study on the design and analysis of a basic heads-up display (HUD) for automotive use. The emphasis will be on the special requirements of a HUD visual system and on the tools and techniques needed to accomplish the design. The first section of this paper will present an overview of the imaging design using commercially available imaging design software. Topics addressed in this section include modeling the windshield, visualizing the imaging performance, using constraints and freeform surfaces to improve the system, and meeting specific visual performance specifications with design/analysis methods. The second section will address the use of a CAD program to design a basic mechanical structure to support and protect the optics. This section will also discuss some of the issues and limitations involved in translating data between a CAD program and a lens design or illumination program. Typical issues that arise include the precision of optical surface prescriptions, surface and material properties, and the management of large data files. In the final section, the combined optical and mechanical package will be considered, using an illumination design program for stray light analysis. The stray light analysis will be directed primarily toward finding, visualizing, and quantifying unexpected ray paths. Techniques for sorting optical ray paths by path length, power, and elements or materials encountered will be discussed, along with methods for estimating the impact of stray light on the optical system performance.

Optical processing using a pair of counterpropagating pulse-shaped spatial solitons to control the molecular structure deep inside an optical material is investigated. A femtosecond pulsed laser focused at the surface of a strontium barium niobate single crystal induces a pulse-shaped self-focusing second-harmonic beam. The two counterpropagating beams are involved in a head-on collision. Locally reversed crystal domains are formed at the collision point, assisted by external threshold controls such as crystal temperature and an electric dc field. The nonlinear interaction between the soliton collision and the approximate nonperiodic reversed domains induces a change in the second-harmonic intensity of the scattered and transmitted beams, thereby enabling the detection of locally reversed crystal domains.

In glass molding, residual stresses, refractive index variation and geometric deviation are inevitable, and result in aberrations. In order to achieve optimal performance, residual stresses, refractive index variation and geometric deviation have to be taken into account simultaneously and reduced into a reasonable level. This paper proposed an integrated procedure to reduce residual stresses, refractive index variation and geometric deviation. Geometry and refractive index predicted by simulation were used to provide feedback to modify the model geometry design. Measurement of geometry, refractive index and residual stresses before and after annealing confirmed that a post molding step is beneficial.

A two-dimensional thin film thickness model based on the geometry of a commercial coater which can calculate more effectively the profiles of linear variable filters (LVFs) has been developed. This is done by isolating the substrate plane as an independent coordinate (local coordinate), while the rotation and translation matrices are used to establish the coordinate transformation and combine the characteristic vector with the step function to build a borderline which can conclude whether the local mask will block the deposition or not. The height of the local mask has been increased up to 40 mm in the proposed model, and two-dimensional simulations are developed to obtain a thin film profile deposition on the substrate inside the evaporation chamber to achieve the specific request of producing a LVF zone width in a more economical way than previously reported.

ITRC dedicates in high precision optics for more than 40 years and focuses in lithography optics for projection system recently. The first project of the lithography optics in ITRC is an i-line Wynne-Dyson projection lens for 3D-ICs applications. The Wynne-Dyson projection lens is a classical design for unity magnification projection system. We take the advantages of the established benefits of Wynne-Dyson lens and modify it. ITRC‘s Wynne-Dyson lens is a 0.16 NA system with unity magnification, which is designed in double telecentricity and long working distance. The projection lens comprises three lenses and one concave mirror. Two aspheric surfaces are deployed in lens 1 and concave mirror. A lens with aspheric surfaces can correct for aberration and deliver a higher performance with fewer lens elements; therefore it has advantages of compact and light. However, aspheres are more difficult to fabricate and higher cost than spherical surface. In order to control the testability and manufacturability of the aspheric surface, the Q-type aspheric surfaces are applied in our design phase and manufacture process. We optimize for both performance and manufacturability by Q-type aspheric surfaces. Not only a testable and manufacturable asphere can be approached but also an additional benefits of less sensitive and cost-effective to manufacture to the required specification. In this paper, the Q-type aspheric surfaces and slope constraint are applied to a Wynne-Dyson projection lens, the testability of Q-type aspheric surfaces by the departure from best-fit-sphere and fringe density of interferometry are estimated. Furthermore, subaperture stitching interferometer system (ASI, from QED technologies) is also applied for testability comparison. The tolerance and sensitivity are also discussed. Finally, the results show a diffraction limit approached lens with testable aspheric surface is designed using Q-type aspheric surface. One of the asphere is 150 m departure from best-fit-sphere in 205 mm clear aperture, that can be tested by subaperture stitching interferometer system (ASI). The alignment tolerance of lens in decenter and tilt can be controlled in the range of ±30 micron and 20 arc-second, respectively.

Laser sources have become indispensable for industrial materials processing applications like surface treatment, cutting or welding to name a few examples. Many of these applications pose different requirements on the delivered laser irradiance distribution. Some applications might not only favor a specific irradiance distribution (e.g. a at-top) but can additionally benefit from time-varying distributions. We present an overview of a recently developed design approach that allows direct calculation of virtually any refractive or reflective laser beam shaping system. The derived analytic solution is fully described by few initial parameters and does allow an increasingly accurate calculation of all optical surfaces. Unlike other existing direct design methods for laser beam shaping, there is almost no limitation in the number of surfaces that can be calculated with this approach. This is of particular importance for optical designs of dynamic systems such as variable optical beam expanders that require four (or more) optical surfaces. Besides conventional static beam shapers, we present direct designs of zoom beam expanders, and as a novelty, a class of dynamic systems that shape and expand the input beam simultaneously. Such dynamic zoom beam shapers consist of a minimal number of optical elements and provide a much more compact solution, yet achieving excellent overall optical performance throughout the full range of zoom positions.

This paper presents a solution for design aspheric multifocal contact lens with various add powers. The multi-aspheric curve on the optical surface profile is replaced by a single freeform spline curve. A cubic spline curve is optimized to remove all unsmooth transitions between different vision correction zones and still satisfy the power distribution of the aspheric multifocal contact lens. The result shows that the contact lens using a cubic spline curve could provide not only a smooth lens surface profile but also a smooth power distribution that is difficultly obtained by an aspheric multifocal contact lens. The proposed contact lens is easily transferred to CAD format for further analysis or manufacture. Results of this study can be further applied for progressive contact lens design.

An optimization process to control the aberration of a concave grating is developed. The approach has a dramatic reduction in aberration and great improvement in spectral resolution.

A free-form surface sub-aperture stitching interferometry (FSSI) is proposed for aspheric and free-form surfaces testing. Different from normal annular and circular sub-aperture stitching method, non-null interferometric configuration and irregular sub-apertures are employed to make the best use of the resolved fringes. Meanwhile, a multi-aperture simultaneous reverse optimizing reconstruction (MSROR) process is proposed for full aperture figure error reconstruction. With the multi-configuration model, full aperture figure error would be extracted in form of Zernike polynomials from sub-apertures wavefront data by the MSROR method. This method concurrently accomplishes sub-aperture retrace error and misalignment correction, requiring neither complex mathematical algorithms, nor sub-aperture overlaps. The experiments show that, the aspheric annular sub-aperture stitching accuracy with the proposed FSSI is more than 1/50λ (rms) comparing with the result of ZYGO Verifier Asphere interferometer. The bi-conic surface sector sub-aperture stitching accuracy is about 1/ 50λ (rms) comparing with result of Taylor Hobson contourgraph in longitudinal section contour.

In this paper, we demonstrated the design method of freeform unobscured reflective imaging systems using the point-bypoint Construction-Iteration (CI) method. Compared with other point-by-point design methods, the light rays of multiple fields and different pupil coordinates are employed in the design. The whole design process starts from a simple initial system consisting of decentered and tilted planes. In the preliminary surfaces-construction stage, the coordinates as well as the surface normals of the feature data points on each freeform surface can be calculated point-by-point directly based on the given object-image relationships. Then, the freeform surfaces are generated through a novel surface fitting method considering both the coordinates and surface normals of the data points. Next, an iterative process is employed to significantly improve the image quality. In this way, an unobscured design with freeform surfaces can be obtained directly, and it can be taken as a good starting point for further optimization. The benefit and feasibility of this design method is demonstrated by two design examples of high-performance freeform unobscured imaging systems. Both two systems have good imaging performance after final design.

The Industrial Revolution, beginning primarily in the UK, generated an increasing need for highly skilled technical people. Throughout the 19th century, technical instruction increased dramatically and the formation of schools specializing in science and technology grew quickly. In England, there was much motivation in favour of a national prestige center for science and technology centered in London. Central among the motivating forces was Queen Victoria’s husband, Prince Albert. Although there were already existing specialist science and technology institutions in major English cities, the growth of superior institutions in other countries within Europe, especially Germany and the Charlottenburg area of Berlin (e.g., the Berlin Technical High School), encouraged important English dignitaries to become more competitive with continental Europe. As a result of this strong continental motivation, several science and technology institutions were built in the south Kensington part of London during the latter half of the 19th century. Imperial College, founded at the start of the 20th century, was a culmination and consolidation of several of these 19th century English institutions. Optical science and technology was an early beneficiary of the founding of Imperial College. This paper will attempt to provide the reader with an understanding of how great was the influence of the optical section of Imperial College in the further development of the world’s optical science and technology.

We have since 2 years ago been doing a research in term of an IR Micrometer Bolometer which aims to fulfill our office, LAPAN, desire to put it as one of payloads into LAPAN’s next micro satellite project, either at LAPAN A4 or at LAPAN A5. Due to the lack of experience on the subject, everything had been initiated by spectral radiance analysis adjusted by catastrophes sources in Indonesia, mainly wild fire (forest fire) and active volcano. Based on the result of the appropriate spectral radiance wavelength, 3.8 – 4 μm, and field of view (FOV), we, then, went through the further analysis, optical analysis. Focusing in illumination matter, the process was done by using Zemax software. Optical pass Interference and Stray light were two things that become our concern throughout the work. They could also be an evaluation of the performance optimization of illumination analysis of our optical design. The results, graphs, show that our design performance is close diffraction limited and the image blur of the geometrical produced by Lapan’s IR Micro Bolometer lenses is in the pixel area range. Therefore, our optical design performance is relatively good and will produce image with high quality. In this paper, the Illumination analysis and process of LAPAN’s Infra Red (IR) Micro Bolometer is presented.

Typical results of the optic simulation are images generated on the virtual sensors of various kinds. As a rule, these images represent two-dimensional distribution of the light values in Cartesian coordinates (luminance, illuminance) or in polar coordinates (luminous intensity). Using the virtual sensors allows making the calculation and design of different kinds of illumination devices, providing stray light analysis, synthesizing of photorealistic images of three-dimensional scenes under the complex illumination generated with optical systems, etc.

Based on rich experience in the development and practical using of computer systems of virtual prototyping and photorealistic visualization the authors formulated a number of basic requirements for the visualization and analysis of the results of light simulations represented as two-dimensional distribution of luminance, illuminance and luminous intensity values. The requirements include the tone mapping operators, pseudo color imaging, visualization of the spherical panorama, regression analysis, the analysis of the image sections and regions, analysis of pixel values, the image data export, etc. All those requirements were successfully satisfied in designed software component for visual analysis of the light simulation results. The module "LumiVue" is an integral part of "Lumicept" modeling system and the corresponding plug-in of computer-aided design and support for CATIA product. A number of visual examples of analysis of calculated two-dimensional distribution of luminous intensity, illuminance and luminance illustrate the article. The examples are results of simulation and design of lighting optical systems, secondary optics for LEDs, stray light analysis, virtual prototyping and photorealistic rendering.

This paper reviews the self-mixing interference (SMI) in terms of its operation principle, the features of SMI signals and its configuration. SMI refers to a phenomenon that occurs when a small fraction of the light emitted by a laser is backscattered or reflected by an external target and re-enters the laser active cavity, thus leading to the modulation of the laser output power. This is a remarkably universal phenomenon, occurring in lasers regardless of type. A few application examples are presented based on the research work done in our group, including SMI sensing for displacement measurement, material parameters and laser parameters. An SMI with the laser operating at the relaxation oscillation is introduced which has potential for achieving more sensitive sensing.

A lateral shearing interferometer based on randomly encoded hybrid grating (REHG) is proposed to measure the optical system aberrations. According to the theory of Fraunhofer diffraction, the REHG is designed to be a combination of a randomly encoded binary amplitude grating and a phase chessboard. Compared with the conventional cross-grating lateral shearing interferometer, the REHG is more suitable for the general aberration testing since no order selection mask is needed. Collimated beam for aberration measurement will converge after passing through the optics system under test. Then the quadriwave lateral shearing interferogram containing the wave-front aberration information is then recorded by the CCD. By selecting its +1 order of the Fourier spectrum in both X and Y directions, the shearing wavefronts in both two orthogonal directions can be obtained employing phase unwarping algorithm. Zernike polynomials are used as basic functions for the original wave-front, and the coefficients of Zernike polynomials can be obtained with shearing wave-fronts. In the experiment, we employed a REHG with a grating pitch of 240μm to test a cemented doublet optics with an aperture of 50mm and a focal lengths of 90mm. The test results showed the peak-to-valley (PTV) aberration is 0.242λ while the root-mean-square (RMS) is 0.064λ. The test results by the REHG are very close to the results by the ZYGO GPI interferometer while the error of PTV is 0.003λ and the error of RMS is 0.007λ. The measurement of optical system aberrations by REHG can reach high precision and exhibit good immunity to environmental disturbance. The REHG can be applied to the optical testing of beam quality, optical system aberration and biomedical research.

This paper presents a comprehensive analysis of the electroluminescence (EL) and current distributions in connection with heat transfer (thermal resistance) in high-power “vertical" and "face-up" AlGaInN light emitting diodes (LEDs). The study was carried out using a combination of high-resolution EL mapping techniques giving information on the lateral distributions of near-field light emission intensity and thermal transient measurements for evaluation of thermal resistance of LEDs and its elements. It was shown that poor current spreading at high current density causes increase in thermal resistance.

A novel scheme of optical phase array(OPA) based on wave-guide is represented in this paper. Fiber paths is main design of system, the single mode fibers are used as transmission paths, photonic crystal fibers(PCF) are adopted as the output array, LiNbO₃ wave-guide is used as the phase modulator. The system configuration have been given in the paper, performance of main device such as LiNbO₃ wave-guide and PCF array are analyzed. According to the theory of OPA and electro-optical effect of LiNbO₃ wave-guide, the feasibility of system have been demonstrated. By adjusting the phase shift of each LiNbO₃ wave-guide, the beam deflection have been observed. Simulation experiments have been implemented to study the influence of its structure parameter on output diffraction characteristics. The results show that the inter-elements distance, the quantity of fiber core and arrangement of fiber core affect the beam steering quality including full width at half-maximum(FWHM), output intensity distribution and normalized amplitude distribution. The grating lobes can be suppressed by smaller distance, the beam scanning accuracy is improved by more units of fiber core. Then two-dimension arrangements of fiber core is analyzed. By adjusting the arrangements of the fiber core, the coupling coefficient and the coupling length between two fiber core in the PCF array are changed, which conduct the different output amplitude distribution. So the structure parameter of PCF array is main factor to the beam steering. With the development of craft for PCF, the research result will provide assistance for the design of OPA in the future.

Shipboard helicopter optical landing guidance system can ensure the safety of landing when the helicopter completed missions. Stray light has a great influence on positional accuracy of the optical landing guidance system. In order to improve the imaging quality of the optical system, the sources of stray light in optical landing guidance system were studied in this paper. Moreover, the effects of stray light on the system were analyzed in detail. The model of the optical landing guidance system was established in TracePro software. 16 different off-axis angles were selected to carry out the ray tracing. Through modeling and simulation, the irradiance of stray light in the imaging plane and the point source transmittance (PST) of the system were obtained; And they were used to evaluate the level of stray light. Results show that the PST of the optical landing guidance system can achieve a level of 10^-5~10^-8 when the off-axis angle is equal to or greater than 49°. At the same time, the solar stray light energy that gets to image plane can achieve a level of 1×10^-4W/m². So the optical landing guidance system can work regularly in this range.

The high precision ray tracing inside inertial confinement fusion (ICF) cryogenic targets plays an important role in the reconstruction of the three-dimensional density distribution by algebraic reconstruction technique (ART) algorithm. The traditional Runge-Kutta methods, which is restricted by the precision of the grid division and the step size of ray tracing, cannot make an accurate calculation in the case of refractive index saltation. In this paper, we propose an improved algorithm of ray tracing based on the Runge-Kutta methods and Snell's law of refraction to achieve high tracing precision. On the boundary of refractive index, we apply Snell's law of refraction and contact point search algorithm to ensure accuracy of the simulation. Inside the cryogenic target, the combination of the Runge-Kutta methods and self-adaptive step algorithm are employed for computation. The original refractive index data, which is used to mesh the target, can be obtained by experimental measurement or priori refractive index distribution function. A finite differential method is performed to calculate the refractive index gradient of mesh nodes, and the distance weighted average interpolation methods is utilized to obtain refractive index and gradient of each point in space. In the simulation, we take ideal ICF target, Luneberg lens and Graded index rod as simulation model to calculate the spot diagram and wavefront map. Compared the simulation results to Zemax, it manifests that the improved algorithm of ray tracing based on the fourth-order Runge-Kutta methods and Snell's law of refraction exhibits high accuracy. The relative error of the spot diagram is 0.2%, and the peak-to-valley (PV) error and the root-mean-square (RMS) error of the wavefront map is less than λ/35 and λ/100, correspondingly.

Space optical images are inevitably degraded by atmospheric turbulence, error of the optical system and motion. In order to get the true image, a novel nonnegativity and support constants recursive inverse filtering (NAS-RIF) algorithm is proposed to restore the degraded image. Firstly，the image noise is weaken by Contourlet denoising algorithm. Secondly, the reliable object support region estimation is used to accelerate the algorithm convergence. We introduce the optimal threshold segmentation technology to improve the object support region. Finally, an object construction limit and the logarithm function are added to enhance algorithm stability. Experimental results demonstrate that, the proposed algorithm can increase the PSNR, and improve the quality of the restored images. The convergence speed of the proposed algorithm is faster than that of the original NAS-RIF algorithm.

Wavefront coding technique as a means of athermalization applied to infrared imaging system, the design of phase plate is the key to system performance. This paper apply the externally compiled programs of ZEMAX to the optimization of phase mask in the normal optical design process, namely defining the evaluation function of wavefront coding system based on the consistency of modulation transfer function (MTF) and improving the speed of optimization by means of the introduction of the mathematical software. User write an external program which computes the evaluation function on account of the powerful computing feature of the mathematical software in order to find the optimal parameters of phase mask, and accelerate convergence through generic algorithm (GA), then use dynamic data exchange (DDE) interface between ZEMAX and mathematical software to realize high-speed data exchanging. The optimization of the rotational symmetric phase mask and the cubic phase mask have been completed by this method, the depth of focus increases nearly 3 times by inserting the rotational symmetric phase mask, while the other system with cubic phase mask can be increased to 10 times, the consistency of MTF decrease obviously, the maximum operating temperature of optimized system range between -40℃-60℃. Results show that this optimization method can be more convenient to define some unconventional optimization goals and fleetly to optimize optical system with special properties due to its externally compiled function and DDE, there will be greater significance for the optimization of unconventional optical system.

In order to ensure the radiometric imaging quality for the space-borne camera with super-wide field of view, we put forward a new method, with which the apparent spectral radiance for any field of view can be precisely calculated. Firstly, building the imaging model for the space-borne camera, and the parameters of the orbits and attitudes of satellite, the look direction for the given field of view, the characteristics of different ground objects, the state of the atmosphere, et al.. Secondly, calculating the geometrical observation parameters for the given look direction of the space-borne camera. Finally, using the radiative transfer model to calculate the value of the apparent spectral radiance. Then, we use this method to calculate the apparent spectral radiance for the space-borne camera with the FOV of 75°based on freeform mirror on a small remote sensing satellite. And the result shows that the relative non-consistency of the apparent spectral radiance can be 25.3%, when the satellite takes the imaging of the area of North Atlantic. And we should greatly consider the characteristic of the radiometric imaging quality for the space-borne camera with super-wide field of view.

Due to the loss of the flexibility of the crystalline lens, presbyopia is the most common vision dysfunction for adults after 40. To correct presbyopia, this paper presents a design of a MIOL, which can give extended clear vision range both in photopic vision(3mm pupil diameter) and in the mesopic vision(4.5mm pupil diameter). With a pseudophakic eye model, a multi-configuration with object distance covering a full range of normal visual from 8m to 0.4m was applied. The surfaces of MIOL were aspherical diffractive surface. MIOL was divided into two regions: the inner zone was optimized when the pupil diameter was 3mm and the outer zone was optimized when the pupil diameter was 4.5mm. Finally, we got a 22 diopters (D) MIOL with a central thickness of 0.652mm and an optical diameter of 4.5mm. By evaluating the modulation transfer function, we got optical performance of the pseudophakic eye with this MIOL. When the pupil diameter of pseudophakic eye was 3mm, MTF at 50c/mm and 100c/mm was respectively above 0.4 and 0.15 for the object distance from 8m to 0.4m. When the pupil diameter of pseudophakic eye was 4.5mm, MTF at 50c/mm and 100c/mm was respectively above 0.25 and 0.09 for the object distance from 8m to 0.4m.The visual acuity was above 0.9 for the whole visual range at both of two pupil diameters. Therefore it is safe to say that the new MIOL design provides good optical performance for whole visual range under both of the photopic vision and the mesopic vision.

Physically accurate lighting simulation requires precise account of the optical properties (BSDF) which are usually measured using gonio-spectrophotometer. In this paper, the authors analyzed the accuracy of BSDF shape measured for later use of measurements in special software for photorealistic visualization and virtual prototyping. Visual and numerical analysis were done. In the first case we look at the sample image rendered under specified lighting conditions, replacing its properties on measurement results and visually estimate the similarity (or difference). In the second case we compare the results of simulation of spatial or angular radiance distribution with results of corresponding radiometric measurements.

Wave-front coding, proposed by Dowski and Cathey in 1995, is widely known to be capable of extending the depth of focus (DOF) of incoherent imaging systems. However, benefiting from its very large point spread function (PSF) generated by a suitably designed phase mask that is added to the aperture plane, wave-front coding could also be used to achieve super-resolution without replacing the current sensor with one of smaller pitch size. An image amplification based super-resolution reconstruction procedure has been specifically designed for wave-front coded imaging systems and its effectiveness has been tested by experiment. For instance, for a focal length of 50 mm and f-number 4.5, objects within the range [5 m, ∞] are clearly imaged with the help of wave-front coding, which indicates a DOF extension ratio of approximately 20. The proposed super-resolution reconstruction procedure produces at least 3× resolution improvement, with the quality of the reconstructed super-resolution image approaching the diffraction limit.

Lateral chromatic aberration (CA) of color cameras has great effects on the imaging quality. This paper presents a novel method to full-field calibrate lateral CA between color channels by using unwrapped phase data. Closed circle sinusoidal fringe patterns having the optimum three-fringe numbers are generated and displayed on a liquid crystal screen consecutively through red, green and blue channels. These closed fringe patterns are captured by a color camera. The wrapped phase and unwrapped phase of each pixel can be calculated by using four-step phase shifting algorithm and optimum three-fringe number method, respectively. The pixel deviations produced by lateral CA are computed by comparing the obtained absolute phase data between red, blue, and green channels in polar coordinate system and calibration is accomplished in Cartesian coordinate system. Lateral CA between color channels of the color camera can be compensated by using the calibrated data. Simulated and experimental results show the validity of the proposed calibration and compensation method.

Nowadays, panoramic annular lens (PAL) applies in aerospace, robotics vision, industrial pipeline endoscope and corporate video conferencing. A cylinder-to-plane projection which called the Flat Cylinder Perspective (FCP) is adopted in PAL. The FCP projected the three-dimensional cylindrical field object onto a two-dimensional annular image plane. The optical system has fade zone in the center of detector. Based on the structure of the PAL system, this paper shows that a panoramic lens is designed with free-form surfaces. In the designed optical system, the local annular object field of view is projected onto a rectangular image plane. The free-form panoramic lens has a wide field of view of 140°in horizontal direction and a field of view of 40°in vertical direction. The design of the panoramic lens can maximize the use of area and have no fade zone in rectangular detector.

Tomographic particle image velocimetry (Tomo-PIV) is a new developed technique for three-component threedimensional (3C-3D) velocity measurement of the flow field based on the optical tomographic reconstruction method, and has been received extensive attention of the related industries. Three-dimensional light source illuminating the tracer particles of flow field is a critical application for tomographic particle image velocimetry. Three-dimensional light source not only determines the size of measurement volume and the range of the scope of application, but also has a great influence on the image quality. In this work, we propose a rectangular light amplification system using powell lens, prisms and two reflectors. The system can be optimized if given the system parameters based on the theoretical model. The rectangular light amplification system will be verified experimentally by measuring the cross section size of the illuminated light source. A 60mm×25mm cross section of rectangular three-dimensional light source can be obtained by using the rectangular light amplification system. The experiments demonstrate the the feasibility the proposed system.

This paper presented a general concentration standard index (GCSI) for 3D TIR lenses, which is introduced as a metric for analyzing the luminous intensity at certain angle, both locally and globally. A Three- Dimensional (3D) slope error tolerance model for TIR lens is constructed and the slope error sensitivities for luminous intensity for different angels are derived. How the slope error impact on the angular candela distribution is obtained with calculation of the slope error impact on the Beam angle (the Full Width at Half Maximum luminous intensity (FWHM)) and the Filed Angle (the Full Width at 10% Maximum luminous intensity). The results revealed that the Beam Angle is decreased at first and then increased with the increased slope error, whereas the Filed angle is monotonically increasing with the slope errors. According theory has been well demonstrated with Monte Carlo ray tracing due to RMS uniformity as low as 1.8% for Beam angle and 2.23% for Filed angle.

The null test of off-axis mirror plays a very important role in off-axis three mirror optical system design. The detection device depends on either complex detection optical system designs or high-precision null lens design. Both can only test one off-axis mirror and are not non-universal. In order to increase the detection efficiency, we innovatively propose a simultaneous null test method of primary mirror and three mirror in off-axis three mirror optical system. The simultaneous null test device is composed of a liquid zoom null lens. Simulation results show that the residual wavefront errors of testing a primary mirror and tertiary mirror are approximately 0.001λ peak-to-valley (PV), and 0.003λ (PV), respectively.

Based on the theory of Jones matrix and the condition of eigenmode self-consistency, we analyze the effect of linear stress birefringence of prismon the beam polarization (described with the ellipticity and loss of the eigenmodes) and null drift (described with the output frequency difference of the eigenmodes) in a TRP resonator. It is found that the linear stress birefringence of prisms can cause larger polarization ellipticity for both CW (clockwise) and CCW (counterclockwise) beams. The results may be useful for designing and optimizing the structure of super high precision TRP ring laser gyroscopes.

Plankton is an important part of the marine life, which plays a significant role in studying the change of global climate and the marine ecological environment. In order to detect plankton accurately and effectively, we design the Underwater In-situ Dark-field Microscopy Detection System based on the principle of dark-field microscopy. The experiment results show that while the 2× microscope objective is used, the resolution is 90.5lp/mm and the horizontal field of view is 2.6×2.6mm and while the 10× microscope objective is used, the resolution is 181lp/mm and the horizontal field of view is 2.2×2.2mm, when the microscope objective is replaced by 0.9× large format telecentric lens, the detection area will be 11mm with the resolution of 32lp/mm. Double compartment structure is designed, such that the system can work underwater.

The design, tolerance sensitivity reduction, assembly, and optical bench test for an oil-immersion microscope objective with long working distance employed in a lattice light-sheet microscope is presented in this paper. In this application, the orthogonal excitation and detection objectives are dipped in an oil medium. The excitation objective focuses the incident laser beam to generate fluorescence on specimen for collecting by detection objective. The excitation objective is custom-designed to meet the requirement specification such as oil-immersion, the long working distance, and numerical aperture (NA) of 0.5, etc. To produce an acceptable point spread function (PSF) for effective excitation, the performance of the objective needs to be close to diffraction limit. Because the tolerance of the modulation transfer function (MTF) is more and more sensitive at higher spatial frequency, it is extremely critical to keep the performance after manufacture. Consequently, an insensitive optical design is very important for relaxing tolerance. We compare the design with and without tolerance sensitivity reduction, and the as-built MTF shows the result. Furthermore, the method for sensitivity reduction is presented. The opto-mechanical design and assembly method are also discussed. Eventually, the objective with five spherical lenses was fabricated. In optical bench test, the depth of the oil is sensitive to MTF, and it leads to the complicated adjustment. For solving this issue, we made an index-matching lens to replace oil for measurement easily. Finally, the measured MTF of the excitation objective can accomplish the requirement specification and successfully employed in a lattice light-sheet microscope.

In our previous works, we presented a zoom system and image stabilization design based on deformable mirrors (DMs). According to the high bandwidth and free edge characteristics of the piezoelectric deformable mirror (PDM), we tested the system’s image-stable capability. We found the PDM could realize some tilt displacements while keeping a certain stable surface shape, it could obtain higher image stabilizing precision when integrated with the traditional mechanical image stabilization systems. In the design of the image stabilization system, the PDM’s tilt displacement range is a key factor for consideration. So in this paper, we carried out a tilt displacement range testing experiment by using the OKO’s 37-channel PDM. We measured and analyzed the variation of the tilt displacements in optical image stabilization process, and calculated the maximum tilt angle as the PDM surface shape was stabilized. We built an experimental platform consisting of a fixed target, an imaging system based on PDM, and a CCD camera. We used the ZYGO interferometer as an evaluation instrument to measure the surface shape stability. When the PDM surface had a tilt displacement, the image point of the fixed target on the camera sensor shifted correspondingly. The tilt angle of the PDM could be obtained by calculating this shift. The results showed that the maximum tilt angle of the PDM was 0.2mrad. The paper also analyzed the experiment errors when concerning about the off-axis error of the PDM deflection center.

The Offner-Chrisp spectrometer is the preferred optical configuration in many spectroscopic imaging applications because it has several advantages over other similar instruments. Freeform surfaces enable imaginative optics by providing abundant degrees of freedom for an optical designer as compared to spherical surfaces, and offer many advantages in imaging application. An Offner-Chrisp imaging spectrometer with freeform surfaces is designed in this paper. The imaging spectrometer works at the wavelength range from 200 to 1500nm. The freeform surfaces are used to reduce the residual aberration over the large wavelength range and achieve a large flat field simultaneously. Different types of freeform surfaces are considered to evaluate their potential, e.g. anamorphic aspherical surface, X-Y polynomial surface and Zernike polynomial surface. Benefits from the freeform surfaces, the residual aberrations are well corrected, especially in the UV region and a flat field over the wide wavelength range is also obtained. The image quality is near diffraction limits. The smile and keystone are also well controlled <0.1μm.

In order to decrease the complexity to design and manufacture the turning grating of the configuration with one reflecting surface, an L-shape two-dimension extended configuration with single plate is given in the paper. This configuration consists of one specular reflecting surface and three holographic gratings two in which periods and the groove orientations are totally same, which makes gratings design and fabrication easier. According to the calculation and analysis to the optical path of configuration, the dimension of the turning grating is no larger than 40mm×30mm. The simulation result demonstrates the display configuration is reasonable and correct and can realize the display effect with 30°×30° field of view and Φ30mm large exit pupil. This configuration can be applied to an Augmented Reality Display (AR) or a Head-Mounted Display (HMD).

Astigmatism and distortion aberrations of conventional Offner-type imaging spectrometer with an in-plane diffraction grating will increase dramatically as its spectral dispersion width so that such spectroscopic mounting is usually suitable for such situation that both slit length and spectrum width are medium and that the spectrum width is less than the slit length. To short slit and high dispersion, novel conical diffraction Offner mounting is more appropriate. Based on the operation principle of this kind mounting, a set of optimized designs, which the focal ratio is 4，the spectral region from 400nm to 900nm, the slit length from 0.5mm to 1mm, and the dispersion width from 9.8mm to 28mm are obtained under the same optical size. To evaluate the imaging quality of the designed and to get the relation between slit length and dispersion width, the merit function and spectral response function are considered. The results show that conical diffraction Offner imaging spectrometers can image well while the spectrum width is less than the slit length, but no more than its 20 times.

With the development of unmanned airborne vehicle (UAV) remote sensing technology, miniature high-resolution imaging spectrometers are greatly needed. In order to improve remote sensing efficiency and get wider coverage, it’s urgent to design and develop fore-optics with wide field of view and waveband for imaging spectrometer. As the refractive system has no central obscuration and it’s conducive to manufacture and assemble, so it’s used for our fore-optics. The key is the correction of secondary spectrum of systems working in broad waveband and meeting the requirement of imagery telecentricity to be appropriate for linear pushbroom imaging system. Suitable glasses are selected on the Glass Map, from where each glass has an Abbe number υ_d and Partial Dispersion. Based on the theory of Gaussian Optics and Seidel third-order aberration theory, the paper derives apochromatic formula, and the power of individual lenses can be calculated. Then with a required value of spherical aberration and coma, this paper derives equations to calculate the initial structure of apochromatic optical systems. Finally, optimized refractive SWIR fore-optics working in 1μm-2.5μm with effective focal length (EFFL) of 11mm is reported. Its full field and F-number are respectively 40°, F/2.8. The system has many advantages such as simple and compact structure, small size, near diffraction-limited imaging quality, small secondary spectrum and imagery telecentricity. Especially it consists of spherical surfaces that can greatly reduce the difficulty and the cost of manufacture as well as test, which is applicable for SWIR imaging spectrometer with wide field of view.

In order to improve the detection accuracy and range of new generation of Forward Looking Infra-Red (FLIR) system for distant targets, its optical system, which usually consists of a fore afocal telescope and rear imaging lenses, is required to has wide spectral range, large entrance pupil aperture, and wide field of view (FOV). In this paper, a new afocal Three-Mirror Anastigmat (TMA) with widened field of view and high demagnification is suggested. Its mechanical structure remains coaxial, but it has zigzag optical axis through properly and slightly decentering and tilting of the three mirrors to avoid its secondary obscuration due to the third mirror as FOV increase. Compared with conventional off-axis TMA, the suggested zigzag-axis TMA is compact, easy-alignment and low-cost.

The design method and optimum result of the suggested afocal TMA is presented. Its initial structural parameters are determined with its first-order relationship and primary aberration theory. Slight and proper decentration and tilt of each mirror is leaded in optimization so that its coaxial mechanical structure is held but attainable FOV and demagnification are respectively as wide and as high as possible. As an example, a 5.5-demagnification zigzag-axis afocal TMA with a wavelength range, an entrance pupil diameter, and FOV respectively from 3μm to 12μm, of 320mm, and 2×3.2 degrees and with a real exit pupil, is designed. Its imaging quality is diffraction limited. It is suitable for fore afocal telescope of the so-called third generation FLIR.

An approach to design a dual-channel two-focal-length lens based on the panoramic annular lens (PAL) structure is presented in this paper. The method of establishing the second channel to eliminate the blind area has been explored in some documents, and mostly it is achieved by utilizing the front surface of the PAL block. But in this paper, we modified the PAL block and divided it into two channels according to their different azimuth direction. These two channels have different focal lengths. Thus, by rotating the system around its axis, optical step-zoom effect can be obtained. Finally, a dual-channel system with a radial zoom ratio of 3× is designed, of which the wide-angle channel has a field-of-view (FOV) of 60° (radial) ×60° (azimuthal) and the long focal length channel has a FOV of 20° (radial)×20° (azimuthal). These two channels share the same stop surface, relay lens, and the image sensor. And a thin glass plate with diffractive structure is placed before the image plane to further correct aberration and obtain a common back focal length for the two channels. This system may have applications in many fields, such as surveillance, robot vision, and foveal imaging.

The primary mirror is an important optical component of space camera. Its performance related to the optical image quality, and the weight directly affects the whole camera weight. The traditional design of primary mirror relies on much experience, lacking of precise theory, and many design parameters obtained by empirical formulas, thus the performance of the result is unstable. For this study, a primary mirror made of SiC with the diameter of 700mm was conceptual designed to get the optimized structure. Then sensitivity analysis was carried out to determine the optimum thickness of the back muscles. Finally, the optimum primary mirror fully satisfied the required was completed, with outstanding mechanical performance and light weight. A comparison between the optimum primary and traditional primary was performed and the results showed that the optimum primary has higher lightweight ratio increased by 5%, higher modal frequency increased by 81Hz.The maximum deformation under gravity reduced by 48nm, PV of the mirror surface reduced by 8.1nm and RMS reduced by 3.1nm. All the results indicated that the optimization method in the paper is reasonable and effective, which gives a reference to the primary mirror design in the future.

The phase diversity wave-front sensing (PDWFS) technique is a posteriori image-based wave-front sensing method which utilizes two images collected simultaneously whose pupil phase differs from each other in a known manner, typically the defocus phase diversity. Here, we present a new method of implementing phase diversity on the sparse aperture imaging system that adds an intentional piston phase to one subaperture. The objective function is firstly derived for the sparse aperture imaging system, then the genetic algorithm is used to minimize the objective function to estimate the piston errors of the subapertures. Digital simulations are conducted for varying amounts of piston phase diversity and levels of noise, the performance of sub-aperture phase diversity is evaluated by comparing with the conventional defocus phase diversity. The results show that the conventional defocus phase diversity performs better than the sub-aperture phase diversity when there is no noise, while the sub-aperture phase diversity outperforms the conventional defocus phase diversity when the noise strength increases. Sub-aperture phase diversity may be an useful alternative if the conventional defocus phase diversity method fails.

An analytical formula model which is used to describe laser beam’s depolarization characteristics is solved based on multiple Rayleigh scattering model. Firstly, by using Stokes vector to characterize intensity and polarization, while at the same time using Mueller matrix and rotation matrix to characterize polarization changing in scattering procedure, a single scattering model is built. Then, a multiple scattering model is built considering the effects of atmospheric absorbing and scattering attenuation. The received light’s Stokes vectors through multiple scattering procedure are separately solved. At last, on the basis of multiple scattering vectors, the depolarization characteristics of laser beam propagation through atmosphere are estimated though calculating ratio of depolarization and polarized angle shifting. The numerical analysis based on analytical conclusion of this paper shows that for a horizontal polarized laser beam, its ratio of depolarization is about 1% and polarized angle shifting is about 0.3。 when propagates through atmosphere and arrives into the receiver on the ground, and both the above characteristics have only a small change compared with the change of cloud’s depth. The findings of these research show that Rayleigh scattering from atmosphere has a weak effect on the laser beam’s polarization status. The multiple scattering model and Stokes vector analytical formulas raised in the paper could also be used to study the depolarization characteristics of ellipse polarized laser beam and partially polarized laser beam propagating through atmosphere. The research findings of this paper will have theoretical guiding significances in the domain of laser communication, laser detection and laser imaging.

Maximum Likelihood Estimation(MLE) is the optimal estimator for Micro-Doppler feature extracting. However, the enormous computational burden of the grid search and the existence of many local maxima of the respective highly nonlinear cost function are harmful for accurate estimation. A new method combining the Mean Likelihood Estimation(MELE) and the Monte Carlo(MC) way is proposed to solve this problem. A closed-form expression to evaluate the parameters which maximize the cost function is derived. Then the compressed likelihood function is designed to obtain the global maximum. Finally，the parameters are estimated by calculating the circular mean of the samples get from MC method. The high dependence of accurate initials and the computational complexity of the iteration algorithms are avoided in this method. Applied to the simulated and experimental data, the proposed method achieves similar performance as MLE but less computational amount. Meanwhile, this method guarantees the global convergence and joint parameter estimation.

Focusing properties of the vector vortex-bearing beams are investigated theoretically by vector diffraction theory. Simulation results show that the intensity distribution in focal region can be altered considerably by adjusting topological charge m and the numerical aperture(NA) of the focusing optical system. Focal pattern evolves from one focal spot to two overlapped intensity peaks¹.The two overlapped intensity peaks separate with increasing topological charge m, which leads to the focal splitting. And focal split appears in focal evolution show that the topological charge of the vector vortex-bearing beams influences the focal intensity distribution considerably, and some novel focal patterns appear.

A Fizeau interferometer based on the self-collimation effect of two-dimensional air-cylinder photonic crystal is discussed theoretically. The Fizeau interferometer includes one total reflection photonic crystal mirrors and two splitters. Compared with non-common optical path interferometer (e.g. Michelson and Sagnac), Fizeau is a type of common optical path interferometer, therefore the machining errors of optical paths lead to little influence on the interference signals. The equi-frequency contours are calculated by using the plane-wave expansion method, and interference properties are investigated by using the finite-difference time-domain method. The curves of the interference signals at output port are determined by the optical path difference of the interferometer. The peaks of the curves are sensitive to the refraction index changes in the optical path, which make it possible to be applied in future high-density photonic integrated circuits, such as air-sensors.

The Wide Field of View Cherenkov Telescope (WFCT) is mainly constituted by optical reflector and focal-plane photomultiplier (PMT) array camera. In order to avoid loss of Cherenkov signal resulting from the dead area between circular PMT tubes and invalid fringe of each PMT, the light concentrator used as front window of PMT is considered to improve detective efficiency. Basing on the edge-ray principle and features of WFCT, several light concentrators are designed and simulated with ZEMAX. The result shows that the hollow hexahedral compound parabolic concentrator (hex-CPC) has good performance in collecting light. Moreover, the samples of the hollow hexahedral CPC have been manufactured and tested.

A method of measuring water colority based on HSV chromaticity (H hue, S saturation, V value) system is proposed. The measurement system is composed of halogen lamp, sample cell and spectrometer. The spectrum data of transmission light captured by spectrometer is used to calculate the XYZ tristimulus values which is then converted to HSV chromaticity. The colority and saturation value shows a good functional relationship which is calibrated in the experiment. Therefore the water colority can be calculated by the saturation in the HSV chromaticity. Since the hue value is acquired at the same time, the method can be adopted to test water sample with different hue. Moreover, the V value is an independent component, so the instability of light source has no influence on the measurement. The colority obtained by the calibrated function coincides with the standard solution.

Chlorophyll fluorescence intensity can be used as seed maturity and quality evaluation indicator. Chlorophyll fluorescence intensity of seed coats is tested to judge the level of chlorophyll content in seeds, and further to judge the maturity and quality of seeds. This research developed a detection system of tomato seeds maturity based on chlorophyll fluorescence spectrum technology, the system included an excitation light source unit, a fluorescent signal acquisition unit and a data processing unit. The excitation light source unit consisted of two high power LEDs, two radiators and two constant current power supplies, and it was designed to excite chlorophyll fluorescence of tomato seeds. The fluorescent signal acquisition unit was made up of a fluorescence spectrometer, an optical fiber, an optical fiber scaffolds and a narrowband filter. The data processing unit mainly included a computer. Tomato fruits of green ripe stage, discoloration stage, firm ripe stage and full ripe stage were harvested, and their seeds were collected directly. In this research, the developed tomato seeds maturity testing system was used to collect fluorescence spectrums of tomato seeds of different maturities. Principal component analysis (PCA) method was utilized to reduce the dimension of spectral data and extract principal components, and PCA was combined with linear discriminant analysis (LDA) to establish discriminant model of tomato seeds maturity, the discriminant accuracy was greater than 90%. Research results show that using chlorophyll fluorescence spectrum technology is feasible for seeds maturity detection, and the developed tomato seeds maturity testing system has high detection accuracy.

Visible light communication (VLC) is one of the hottest research directions in wireless communication. It is safe, fast and free of electromagnetic interference. We carry out the visible light communication using DFTS-OFDM modulation mode through the headset port to and take equalization technique to compensate the channel. In this paper, we first test the feasibility of the DFTS-OFDM modulated VLC system by analyzing the constellation and the transmission error rate via the headset interface of the smartphone. Then we change the peak value of the signal generated by the AWG as well as the static current to find the best working point. We tested the effect of changing the up-sample number on the BER performance of the communication system, and compared the BER performance of 16QAM and 8QAM modulation in different equalization method. We also do experiment to find how distance affect the performance of the communication and the maximum communication rate that can be achieved. We successfully demonstrated a visible light communication system detected by a headset port of a smart phone for a 32QAM DFTS-OFDM modulated signal of 27.5kb/s over a 3-meter free space transmission. The light source is traditional phosphorescent white LED. This result, as far as we know, is the highest data rate of VLC system via headset port detection.

Most current virtual reality (VR) interactions are realized with the hand-held input device which leads to a low degree of presence. There is other solutions using sensors like Leap Motion to recognize the gestures of users in order to interact in a more natural way, but the navigation in these systems is still a problem, because they fail to map the actual walking to virtual walking only with a partial body of the user represented in the synthetic environment. Therefore, we propose a system in which users can walk around in the virtual environment as a humanoid model, selecting menu items and manipulating with the virtual objects using natural hand gestures. With a Kinect depth camera, the system tracks the joints of the user, mapping them to a full virtual body which follows the move of the tracked user. The movements of the feet can be detected to determine whether the user is in walking state, so that the walking of model in the virtual world can be activated and stopped by means of animation control in Unity engine. This method frees the hands of users comparing to traditional navigation way using hand-held device. We use the point cloud data getting from Kinect depth camera to recognize the gestures of users, such as swiping, pressing and manipulating virtual objects. Combining the full body tracking and gestures recognition using Kinect, we achieve our interactive VR system in Unity engine with a high degree of presence.