This PDF file contains the front matter associated with SPIE Proceedings Volume 11104, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

A head-mounted display (HMD) requires a large field of view (FOV) and a large exit pupil diameter while maintaining a compact structure. In this paper, we show a head-mounted display design comprising two freeform mirrors covering a 28° full field-of-view with an eye relief of 15mm. The simplified partial differential equation (PDE) method is applied in the design of a two-mirror HMD system. Then the data points on the unknown freeform mirrors are calculated using the rays from multiple fields and are used to construct the freeform mirrors in the HMD system, which is taken as a starting point. This simplified partial differential equation method makes calculations easier. The anamorphic surface and the XY polynomial freeform surface are used in the two freeform mirrors for improving the image quality, respectively. The optimization strategy is also described in detail. The final HMD system operates at F/3.75 with 8mm exit pupil diameter achieving good imaging performance.

Most lens design problems involve the time-consuming task of finding a proper starting point, that is, a lens design that approximately fulfills the desired first-order specifications while decently correcting aberrations. In recent work, a fully-connected (FC) deep neural network was trained to learn this task by extrapolating from known lens design databases. Here, we introduce a new dynamic neural-network architecture for the starting point problem which is based on a recurrent neural network (RNN) architecture. As we show, the dynamic network can learn to infer good starting points on many lens design structures at once whereas the previous model was limited to a given sequence of glass elements and air gaps. We also show that a pretrained RNN model can generalize its knowledge over new lens design structures for which we have no reference lens design and obtain a significantly better optical performance than a RNN trained from scratch.

We present an overview of the pros and cons of using GPUs in optical design software. While GPUs can run multiple calculations in parallel, that parallelization comes with a price. We will discuss the trade-offs that allow GPUs to run up to thousands of cores in parallel and how those trade-offs effect the use of GPUs in optical design software. In particular, we review the use of GPUs in several steps of design calculations, including ray-tracing and computationally expensive steps such as calculating Huygens integrals.

Wavefront coding is a hybrid optical-computational technique that makes use of a phase modulating element in conjunction with a deconvolution algorithm to extend the depth of focus of imaging systems. The phase mask codes the wave-front in such a way that the point-spread function do not change appreciably as a function of defocus. In this work, the modulation is introduced by phase masks in the shape of a subset of Jacobi-Fourier polynomials. We will show, by both numerical simulations and experiments that the Jacobi-Fourier polynomial phase masks are good candidates for high-resolution images under noise presence.

Miniature optics are used in many applications and particularly in consumer optics for such products as webcams, mobile phones, automotive components, endoscopes, tablets, and many other connected devices. Mobile phone cameras are probably the ones that have driven the race for shorter TTL over the past 10 years. Ten years ago, cell phone cameras were composed of 3-4 optical plastic elements within one camera lens; today it takes more than 6 optical elements to obtain mega pixel resolution. But it is still not enough. The market has an insatiable appetite for greater optical performance. Consequently, the lens system has become more complex and now may require more optical elements with more complex optical functions. In this context, can the metasurface lens play a role? In this paper, we will try to address this question and discuss how metasurfaces promise to become a game changer in the consumer electronics market.

This work proposes a lens topology based on the addition of combined high-order aberrations to its posterior surface to achieve an extended depth of focus. The added terms are vertical and horizontal coma and spherical aberration, described by Zernike polynomials. We compare the herein proposed IOL with three classes of IOLs available on the market: monofocal, multifocal and extended depth of focus (EDoF). The proposed lens showed better results off the image plane, confirming the increase in the depth of focus when compared with the monofocal IOL. This is clearly observed with the extended Through-Focus-MTF maps that allow the evaluation of several spatial frequencies at different image planes. The fabricated prototype has similar performance to the Tecnis Symfony, a commercial lens with extended depth of focus. And when the Modulation Transfer Function (MTF) is compared to multifocal lenses, a niche where lenses with extended depth of focus can be possible substitutes, the performance of the herein proposed lens was higher in every case considered.

Directed energy propulsion for interstellar travel has been proposed as an ideal method for reaching appreciable speeds relative to the speed of light: 0.2c. However, the amount of energy required necessitates a large aperture, on the order of kilometers, while mitigation of atmospheric perturbations requires a discretization of the aperture into many individual laser elements. The use of fiber lasers for these elements obligates mode-matching the fiber to the desired 10 cm aperture for a collimated beam. Various collimation systems were designed and compared. A 3-lens system with one achromat and two aspheric lenses, with two of the lenses used as a Keplerian telescope to achieve a system-shortening effect was analyzed. A similar system made with a plano-convex lens replacing the large-aperture aspheric lens with two additional compensating lenses was compared. A single diffractive optic operating at F/8 was likewise considered. The optical performance of these systems was compared, as was the cost-effectiveness. Scalability to millions of elements was required, so cost-per-system was a crucial consideration factor. Possible manufacturing processes for a diffractive system were investigated, and stamping processes for replication were analyzed to determine the possibility of replication of such an optic reliably, cheaply, and with acceptable results.

Fundus cameras are the current clinical standard for capturing retinal images, which are used to diagnose a variety of sight-threatening conditions. Traditional fundus cameras are not easily transported, making them unsuitable for field use. In addition, traditional fundus cameras are expensive. Due to this, a variety of technologies have been developed such as the D-EYE Digital Ophthalmoscope (D-EYE Srl, Padova, Italy) which is compatible with various cellphone cameras. This paper reports on the comparison of the image quality of the Nidek RS-330 OCT Retina Scan Duo (Nidek, Tokyo, Japan) and the D-EYE paired with an iPhone 6 (Apple, Cupertino, USA). Twenty-one participants were enrolled in the study of whom 14 underwent nonmydriatic and mydriatic imaging with the D-EYE and the Nidek. Seven participants underwent nonmydriatic imaging with the D-EYE and the Nidek. The images were co-registered and cropped so that the region of interest was equal in both the D-EYE and Nidek images, as the D-EYE had a smaller field of view. Using the Nidek image as the reference, objective full-reference image quality analysis was performed. Metrics such as structural similarity index and peak signal noise ratio were obtained. It was found that the image quality of the D-EYE is limited by the attached iPhone camera, and is lower when compared to the Nidek. Quantification of the differences between the D-EYE and Nidek allows for targeted development of smartphone camera attachments that can help to bridge the current gap in image quality.

Fluidic lenses offer tunability and flexibility that are not available with conventional solid lenses. The development of a variable focus lens has the potential for replacing bulky optical systems and allows the miniaturization of imaging optics used in digital cameras and mobile phone cameras. In this paper, a liquid lens platform for use in an undergraduate laboratory setting is presented. A variable lens is prepared by injecting water into bulk polydimethylsiloxane (PDMS) that remains uncured in its fluid state. We report the tunable focusing ability of this simple liquid lens system and analyze the change in focal length as a function of injected water volume. The water-PDMS interface acts as a diverging lens, in agreement with ray tracing analysis based on curvature and refractive indices. Variable focal lengths are measured with an optical set-up employing a helium-neon laser and a solid converging lens with focal length = 2.5 cm. By increasing the water volume from 0.05 to 0.30 ml, we are able to tune the focal length from -6.5 mm to -10.6 mm. Lens geometry remains spherical as the curvature of the lens changes with the addition of water. Our experiments coincide with a simple theoretical framework for a thick lens immersed in a medium. The water-PDMS lens is a promising component of basic and advanced experiments in an undergraduate optics course.

A Wavefront Coding microscopy system is implemented in order to extend the depth of field of an optical system. An LC - SLM is used to display the profile of a phase mask. A set of optically coded images is recorded in an axial range [−1, 1.5] mm. To accelerate the deconvolution process, a routine developed directly on a GPU is implemented. Using this GPU based approach, the deconvolution time is reduced by providing an additional speed up to the visualization. Digital images are acquired using an experimental setup and results are presented.

This paper reports on the exposure of visible wavelength camera optical elements to a simulated orbital radiation environment in support of the Restore-L flight project at NASA’s Goddard Space Flight Center. Borosilicate glasses with various metal oxide dopants - S-LAL8, S-LAL18, N-SF1, and the polycarbonate material Makrolon GP were exposed to electrons and protons of varying energies. Low energy (E ≤ 10keV) charged particles were used primarily to assess degradation to the antireflective coatings of the optical elements. High energy (E ~ 1 MeV) charged particles were used to evaluate degradation to the bulk material. Elements of S-LAL18, N-SF1, LaK9G15, and Makrolon GP were exposed to a representative atomic oxygen rich environment. Elements of S-LAL8 and Makrolon GP were exposed to intense ultraviolet radiation. Pre- and post-exposure transmittance measurements were used to quantify the effects on the elements tested in the simulated environment over the 0.3 to 1.2 micron wavelength range. Our measurement results will be discussed in the context of their robustness to the orbital environment and the known chemical constituents of the materials tested.

The design of four mirrors anti-astigmatism astronomical telescope is carried out for low earth orbit satellite. By integrating with Cassagrain and Schwartzschild configurations, the telescope is design. It contains four mirrors with conic surface, to form an aberration free. The system contains two parts: first part is the Cassagrain type telescope for pick up the ground object to the stop position, and the second part is Schwartzschild configurations as relay optics, which is to relay the image to high resolution CCD sensor to provide 0.5 ground space distance image. The system is symmetric with aberration free within a one cubic size fitted for small satellite. The optic mechanical is simple easy to assemble for optical calibration, while the body is rigid in space.

Minimal refractive index data in the near-infrared spectrum are available for optical plastics. Typically, refractive index measurements are made by fabricating a prism of candidate optical material and using appropriate metrology equipment. Few plastics are available in thicknesses adequate to fabricate appropriate size prisms; however, almost all optical plastics can be acquired in a flat plate form. The investigation considered two fundamental approaches to measure the refractive index by (i) rotating a flat plate and measure the beam displacement and (ii) measuring the optical focal shift. The rotation method was determined not accurate enough. An optical focal shift method optical mechanical (n t_optical / t_mechanical ) = was developed that utilized existing laboratory equipment. The shift of focus when the plastic plate sample was inserted was located by determining the position of maximum contrast of the projection of a Ronchi ruling target when illuminated by flux from a Cary Eclipse covering the spectral range of 550–975 nm. The instrumentation, data processing, and measurement performance are presented.

A silicon Fresnel lens was designed and fabricated using a greyscale lithography technique to shape optical emissions from an edge-emitting semiconductor diode laser. The laser beam was collimated in the fast axis and allowed a ±3° divergence in the slow axis along with bias angle accomplished through lens decentering. The lens had an aperture of 6.8 mm × 2.2 mm and 1 mm in total thickness. The lens was first designed as a contiguous surface using conventional raytracing methods, and then converted to a Fresnel sag model with an etch depth of 6.25 micrometers. The sag model along with the manufacturing tolerances were fed back through numerical tools to refine the design and modify the lens shape and laser position. Optical profilometry of fabricated lens element found deviations from design and nonuniformity across the entire aperture, with over-etching in the center and under-etching toward the edge of the lens. Characterization of the fabricated lenses showed less than 5% deviation in etch depth. Collimation performance was measured to be less than 2 milliradians, which was in close agreement with design models. Greyscale fabrication of the lens element enabled complex curvatures to be combined and provided a compact solution for direct, single optic coupling of diode laser to free-space projection.

In this paper, we present the main results for the theoretical, numerical and experimental analysis of a new method to measure the roughness of metal surfaces. The requirements for a waveguide optical resonator, which is the main optical node of the device implementing this method, have been developed. A comparative analysis of two different designs of an optical node is performed. The energy spectra of the roughness of various surfaces were measured. As a result of the research, the main advantages of the method under consideration and practical recommendations are provided to improve the design of the device that implements this method.

Bidirectional scattering distribution function (BSDF) represents the scattered light distribution in forward and backward directions. BSDF is an important function in precise lighting design, because surface scattering is difficult to determine and including it in simulations. However, to measure a whole field BSDF is time consuming, as it can take as long as a day. In this paper, we propose and demonstrate a new way to measure BSDF. We utilize a screen that is illuminated by the scattered light, and a camera that captures the image on the screen. A complex calibration between the grey level of the camera and intensity is performed to make sure the measurement is valid. Through continuously imaging the screen for various scattered light distributions, an image fusion is performed to present the final BSDF. We call this instrument as screen image synthesis (SIS) BSDF meter. In this paper, two generations of SIS BSDF meter was developed, and is shown in details.

In this paper, a primary lens of concentrator photovoltaic (CPV) system is designed by using freeform optics. The designed lens is constructed based on a basic idea of a combination of Fresnel lens and freeform optics, in which the lens is divided into an array of sub-lenses, which are designed using the conservation of optical path length and the edge ray theorem to get uniform irradiance distribution over the receiver. In this design, every sub-lens is designed to guide the direct sunlight over the receiver with uniform irradiance so that the whole of the primary lens will converge uniformly the direct sunlight over the receiver. The structure of the lens is designed firstly by using Matlab program for every sub-lens. The Matlab data of the designed lens structure is then used to build the three-dimensional (3D) lens in LightTools™ software. The ray tracing technique in LightTools™ software is used to find out the optimum structure of the freeform lens. Furthermore, the simulation is performed to estimate the efficiency of the lens as a concentrator of a CPV system by using the light source with the sunlight spectrum. The designed lens can achieve high geometrical concentration ratio and uniform irradiance distribution over the receiver. The simulation results show that the lens can easily reach a high concentration ratio (494 times) with uniform irradiance distribution and good optical efficiency (86%).

We proposed a novel structure to perform photon recycling for a double-light-source illumination system pumped by a laser. In the design, two kinds of phosphor are located at the two focus of an elliptical reflective surface separately, after the phosphor on the first focus pumped by laser, the backward scattering light will refocus at the other phosphor layer at the second focus. The absorption spectrum of the second phosphor should fit that of the emission light by the first phosphor. When the emission spectrum covers red light, the whole system is a double-light-source module.

Remote downconverters such as phosphors or quantum dots that are physically separated from the blue light-emitting diode (LED) chips can strongly enhance the luminescence efficiency of solid-state lighting (SSL) and liquid-crystal displays (LCDs) because of their reduced light reabsorption. However, the high cost of traditional remote downconverters has limited their wide adoptions in these applications. Herein, we report a one-step, general synthesis method that can convert commercial light-diffusing polymer microspheres into highly luminescent perovskite-based downconverters at an extremely low cost. Involving a quick antisolvent-induced heterogeneous nucleation, our method creates well-dispersed perovskite nanoparticles anchored onto polymer microspheres and the whole process takes only several seconds at room temperature without any complex experimental setups. Significantly, the as-synthesized perovskite-on-polymer microspheres offer widely tunable, highly saturated colors with light-diffusing capability. The pure green-emitting CsPbBr₃ manifests a high PL quantum yield of 70.6% and superior stability in water is also demonstrated. With these very saturated colors, we propose two configurations of integrating these microspheres into SSL systems. Further optimizations demonstrate that highly efficient, excellent color-rendering, and circadian lighting can be achieved. Thus, these luminescent microspheres hold great promise to be adopted as a low-cost, high-quality replacement for the traditional, expensive remote downconverters in SSL, LCDs and beyond.

In this paper, an efficient lighting design for indoor sport field is presented. The average illuminance for the indoor sport field with eight playing courts can be achieve to 500 lx at a 11.2 m of the lamp's mounting height. Besides, because of specific arrangement of luminaires, the proposed lighting design can effectively reduced the glare effect and provide a comfortable illumination to players.

The development of laser technologies defined the novel quality demands to optical interference coatings. For many technological applications is very important to use lasers with equal distribution of laser intensity across the beam. Gradient mirrors is one of the most simple and convenient means to manage spatial distribution of laser radiation, and can be used in various lasers and laser devices. These mirrors are used as output coupler in the laser cavity to form radiation close to the Gaussian distribution which using radially varying thickness that have been proved the most practical. Multilayer dielectric mirrors with a smooth changing reflection are used in various types of laser resonators. However, in practice, not equal distributions take place especially for Q-switch lasers. It can be arise due to as mode structure of laser irradiation, as optical defects of rod. So, application of such mirrors, permit realize the selection of transverse modes in which the minimal losses possess the transverse mode with amplitude distribution close to distribution of mirror reflection. This paper presents the methodology of fabricating multilayer dielectric mirror with altering over surface parameters of reflectance.

To compensate the spherical aberration of the eye using the conic constant of the first surface of a contact lens for different refractive errors. Refractive errors were simulated by modifying only the first curvature of the cornea. For every refractive error was calculating Zernike polynomials using Optics Software for Layout and Optimization (OSLO) EDU edition with and without contact lens. To calculate the conic constant of the contact lens we use the Seidel sums for thin lenses from the longitudinal spherical aberration as it proposes V. Mahajan. The value of Zernike spherical aberration coefficient for the eye with farsightedness (+ 5.00 D) + spherical contact lens was 0.142691 μm. The conic constant value to compensate the spherical aberration was -0.222995 and the value of Zernike spherical aberration coefficient of the eye + aspherical contact lens was 0.004354 μm. The value of Zernike spherical aberration coefficient for the eye with myopia (- 5.00 D) + spherical contact lens was 0.144505 μm. The conic constant value to compensate the spherical aberration was -0.101424 and the value of Zernike spherical aberration coefficient of the eye + aspherical contact lens was 0.072820 μm. The proposed method allows us to design contact lenses that compensate for the spherical aberration of the eye from the Zernike polynomials. Although the design of contact lenses is to third order, we obtain a smaller spherical aberration than the chromatic aberration on the axis without use optimization routine.

We present the general formula to generated aspheric collimator lens free of spherical aberration and astigmatism. The presented formula describes the second surface of the aspheric singlet such as it correct the spherical aberration generated and astigmatism by the first surface of the singlet.

This paper presents the theory for numerical evaluation of the spatial resolution along an optical axis of an optical microscope in case of oblique illumination. It considers the optical setup with a coherent light source, a microscope condenser, a grating located in a plane with an optical axis and with grating slits perpendicular to this axis and a microscope objective. It is proposed the analytical expression for calculation of the minimal resolvable period of this grating or the corresponded spatial cutoff frequency that characterizes the spatial resolution along the optical axis. It is demonstrated that this spatial cutoff frequency is not proportional to the angle of beam inclination. The proposed theory clearly explains why an optical microscope has the limited spatial resolution along an optical axis and how illumination can maximize this resolution.

This study presents a new method for selecting a pair of optical glass and housing material to achromatize and athermalize a lens system, by use of the factor of determination for material selection. To effectively obtain an optimum combination for materials, we newly propose the sequential material selection method by introducing the factor of determination for material selection, which depends on the level of contribution to correct these aberrations and the availability to be used as a suitable material. Even though there are many cases for material combinations, we can sequentially identify the best pair of glass and housing materials by checking the factor of determination. Using this design approach, we efficiently obtain an achromatic and athermal system through an optimum combination of materials, over the specified ranges in temperature and waveband.

Retinal examination using direct ophthalmoscope is preferred over other techniques for screening purposes because of its portability and high magnification, despite its power sustainability and cost issues. With increasing number of low-cost sustainable devices available in the market, it is important to assess the efficacy of the devices. We compared three devices - Arclight ophthalmoscope, a D-Eye attached to iPhone 6, and conventional ophthalmoscope Heine K180 - in terms of ease of examination, usage, field of view, color rendition, patient comfort, length of examination, and closeness to the eye. Two trained optometrists examined 26 undilated eyes and graded the ease of retinal examination, ease of use and assessed vertical cup:disc ratio (VCDR). Patients reported their comfort level in terms of glare produced by the light source, length of examination and closeness to the eye. The examiners had a good agreement for all assessments. Of 26 eyes, VCDR assessment was not possible in 10/26 (38.4%) of the examinations, in (3/26, 11.5%) examinations with Arclight, in 0/26 examinations with D-Eye. Ease of use score was higher for Arclight and D-Eye than Heine. D-Eye had a relatively larger field of view than other 2 devices. Heine ranked first in color rendition. The luminance level of the high-beam setting of Arclight was more than twice that of Heine and D-Eye. Despite that, the patients reported experiencing uncomfortable glare in Heine (14/26, 53.8%), significant glare with Arclight (16/26, 61.5%) and some/no glare with D-Eye. The examination time was shorter when using D-Eye. Overall, D-Eye scored better in most of the evaluation items followed by Arclight.

Nowadays, breast lesions are a common health problem among women. Breast thermograms are images recorded by digital-optical systems with high resolution that use infrared technology in order to show vascular and temperature changes. In the present work, we study benign and malignant breast lesions shape by means of fractal analysis. The Fractal Dimension (FD) is calculated with the Box Counting method and the Hurst exponent is obtained using the Wavelet coefficients and the Detrending Moving Average algorithm. These algorithms was applied to synthetic images and breast thermograms. The Fractal Dimension value is used for patient classification with or without breast injury. The proposed methodology was applied to the Database For Mastology Research (DMR) in order to classify thermographic images. The FD of ROIs for breast thermograms was calculated. Results shows that the FD BCM values ranges from [0.45,0.81] in 4 healthy cases and from [0.92,1.33] in 4 unhealthy cases.

Urban growth, deforestation, water resources and thawing of the poles due to globe worming are topics of interest in the research community. Normalize difference indices are utilized in remote sensing to analyzed and classify surface cover types. In this paper research, a multispectral satellite data from Landsat 5 TM is preprocessing, in order to addresses and evaluates accuracy of Normalized difference Built-up Index (NDBI), Normalized Difference Vegetation Index (NDVI), Automated Water Extraction Index (AWEI) and Normalized Difference Snow Index (NDSI) at different time scenes. A quantitative statistical pixel percentages of build-up, vegetation cover, snow/ice and water body is given in this study for different periods of time.

We present the results of this study of a calculation model built for predicting the spectrum of white-light LED (WLLED) with different concentration formula of three kinds of the phosphor. First, we analyze the spectrum of the blue light LED with different penetrating concentrations of the phosphor. Next, we analyze the emission spectrum after absorption of blue light by the phosphor and the re-absorption effect. Then, we introduce the re-absorption effect into the superimposed spectrum of blue light and the emitting light. Finally, we compare the superimposed spectrum with the experimental result. By this method, we can predict the behavior of the WLLED, such as optical efficiency, chromaticity coordinates, correlated color temperature (CCT), and color rendering. Thus, we obtain the weight ratio of the multi-color mixed phosphor (MCP) of high color rendering WLLED.