Due to the problems of long iteration time and poor image quality in the traditional infrared multispectral image reconstruction method based on compressed sensing(CS), an auto-encoders network based on residuals is proposed. Autoencoders are unsupervised neural networks where the output and input layers share the same number of nodes, and which can reconstruct its own inputs through encoder and decoder functions. using code decoding technique learn from real infrared multispectral image spectrum information, through the fast image reconstruction of auto-encoder, get high quality image. The performance of the method is verified by using multiple infrared multispectral images. The results show that the method has the advantages of high image processing efficiency and high spatial resolution. Compared with the traditional compressed sensing method, the auto-encoder network based on residuals has better effect on infrared multispectral image reconstruction.
The segmented planar imaging method is a new imaging concept based on Van Cittert-Zernike theory that offers significantly reduced size, weight, and power consumption compared to a traditional imaging system and aims to realize high resolution imaging. In this paper, the segmented planar imaging detector (SPID) imaging process has been accurately modeled and quantitatively analyzed to image quality enhancement. The influences of the longest interferometer baseline and the spectral channel number of array wave-guide grating(AWG) on the imaging quality of the SPID have been analyzed. It is verified that the cut off spatial frequency and the resolution of the SPID system is determined by the longest interferometer baseline Bmax. The imaging process of different Bmax have been numerical simulated to evaluate the impact of longest interferometer baseline on the SPID system, and the reconstruction image shows that the imaging quality can be improved by increasing the longest interferometer baseline. Also, the numerical simulations of different number of spectral channels of AWG have been operated, and the results showed that the visibility of interference fringes and spatial frequency coverage points are increased with the increasing number of spectral channels. Therefore, the imaging quality improved with the increasing number of spectral channel of AWG. In conclusions, the research results will provide theoretical and technical supports for segmented planar integral optical imaging system development.
Optical phased arrays can achieve inertialess, high-resolution, flexible beam steering required by a broad range of applications, such as laser radar, free space optical communication and interconnect, and laser projection displays. In this paper, we study the SOI and GaAs waveguide optical phased arrays (WOPAs) comparatively. The principle of the phase shifter is investigated based on the thermo-optic effect in silicon waveguides and electro-optic effect in GaAs waveguides. The propagation properties of optical field in the two kinds of WOPAs are studied numerically, including the guided modes, the propagation of optical field in single waveguide and the coupling properties of optical field in waveguide arrays. We also analyze the performance of the two kinds of WOPAs. Silicon WOPAs show superiorities of low propagation loss and wide beam scanning range, while GaAs WOPAs show superiorities of fast beam scanning speed. This research provides a valuable reference for the chip design of optical phased arrays.
We presented three-dimensional image including reflectivity and depth image of a target with two traditional optical imaging systems based on time-correlated single photon counting technique (TCSPC), when it was illuminated by a MHz repetition rate pulsed laser source. The first one is bi-static system of which transmitted and received beams path are separated. Another one called mono-static system of which transmit and receive channels are coaxial, so it was also named by transceiver system. Experimental results produced by both systems showed that the mono-static system had more advantages of less noise from ambient light and no limitation about field area of view. While in practical applications, the target was far away leading to there were few photons return which was prejudicial to build 3D images with traditional imaging system. Thus an advanced one named first photon system was presented. This one was also a mono-static system on hardware system structure, but the control system structure was different with traditional transceiver system described in this paper. The difference was that the first return photon per pixel was recorded across system with first photon system, instead of overall return photons per pixel. That’s to say only one detected return photon is needed for per pixel of this system to rebuild 3D images of target with less energy and time.
Based on previous researches, we construct a pseudo-thermal light ghost imaging system suited for remote imaging applications. By using pulsed pseudo-thermal light, the transmitted power is improved to ghost imaging long distant targets. By using imaging lens system, the path lengths of reference and signal light need not keep equal, as in lensless ghost imaging system, thus the transmitter, receiver, and correlator circuit can be integrated and keep compact. Furthermore, the revolution is improved by reducing the sizes of speckles. And the number of imaging frames is decreased (thus reduced the image-reconstruct time) and the signal-noise-ratio of ghost image is improved by compressed sensing. Based on the constructed experimental system, we implemented ghost imaging of a target at about 30m range.
Based on the four-wave mixing mechanism and light fanning effect, a mutually pumped phase conjugator(MPPC) model
is proposed to analyze the variation of MPPC output response with time for different scattering seed value. It shows that
preset grating can enhance the fan light intensity when it satisfies Bragg condition and also can shorten MPPC response
time. In experiment the bird-wings MPPC is done with or without the preset grating and the variation of MPPC
reflectivity with time is obtained in two cases, and simulation conclusion is in agreement with the experimental result.
These results have importance for applications of MPPC on optical heterodyne detection.
KEYWORDS: Signal to noise ratio, Eye models, Visualization, IRIS Consortium, Visual process modeling, Eye, Human vision and color perception, Imaging systems, Infrared imaging, Systems modeling
The relationship between correct discrimination probability of the human eye and perceivable signal-to-noise (SNR) threshold is studied for different equilateral triangle sizes with specified luminance through combining theoretical calculation with practical experiment based on triangle orientation discrimination (TOD) performance evaluation method. Specifically, the simulation images of triangle patterns are generated by an infrared imaging system (IRIS) simulation model. And the perceivable SNRs for these images are calculated by establishing the system theoretical model and the human vision system model. Meanwhile, the Four-Alternative Forced-Choice experiment is performed. Experiment results of several observers are averaged statistically and the curves of perceivable SNR threshold which change with the correct discrimination probability are obtained. Finally, the analyses of these results show that these changes are in accordance with the psychometric function and that the fitting curves become steep with the increase of triangle sizes. These data and conclusions are helpful to modify the existing TOD performance model of an IRIS.
Based on the four-wave mixing mechanism and fanning effect, the threshold coupling constant for mutually pumped
phase conjugator (MPPC) with one interaction region and two interaction regions is studied in theory. The relation of the
the threshold coupling strength for MPPC and the fanning intensity is studied. Due to the more efficient fanning, preset
grating in MPPC has the ability to reduce threshold coupling constant and improve output efficiency. These
characteristics predicted by theory have been used to explain the previous experiment phenomenon. The dependence of
threshold coupling constants for MPPC on the amplitude ratio of incident pump beams is presented. The threshold
coupling constant for one-interaction-region MPPC is lower than that for two-interaction-regions MPPC.
The photorefractive adaptive optical heterodyne detection system (PAOHDS) is proposed. The dynamic properties of
mutually pumped phase conjugate (MPPC), the key technology to the PAOHDS, are studied theoretically. The
three-dimensional distribution of MPPC refraction index grating in time and length axis is simulated numerically. The
dependence of dynamic properties of MPPC on the intensity of the fanning light is presented.The stronger the intensity
of the fanning light is, the less response time for MPPC is. The dependence of dynamic properties of MPPC on the
coupling strength is presented. The greater the coupling strength is, the less response time for MPPC is. These results
provide theoretical basis to reduce response time of PAOHDS.
A new technique for recording hologram is proposed. The recording system looks like in-line holography, while the recording
results are the off-axis holograms. The reference beam comes from the object wave itself, therefore the hologram is named self
reference hologram. The principle is discussed briefly and demonstrated experimentally.
The phase conjugation properties of self-pumped phase conjugation (SPPC), mutually pumped phase conjugation
(MPPC), SPPC and MPPC coexisting are researched in Cu:KNSBN crystal with Q-switched single longitudinal mode
YAG pulse laser pumping. The dependence of the reflectivity of phase conjugation on the incidence position and angle
are obtained experimentally. The results show the optimal incident parameter exists in photorefractive phase
conjugation effect.
Based on the physical mechanisms of femtosecond laser-transparent materials interactions, three kinds of micromachining including three dimensional data storage, optical waveguide network and grating with an amplified Ti:sapphire laser system are presented. These optical devices on different transparent materials by femtosecond pulses are featured. The effect of laser machined parameters such as irradiated energy, the scanning speed and the recording material upon fabricated optical devices is studied in detail. From examples, the versatility of femtosecond laser precise micromachining technique is demonstrated. Practical application of femtosecond laser materials processing is illuminated.
We present for the first time, to the best of our knowledge, active waveguide device and array in Er3+-Yb3+ codoped lithium silicate glass directly written by near-IR femtosecond laser pulses. We show that in Er3+-Yb3+ codoped lithium silicate cylinder waveguide of diameter 4um is produced by use of a microscope objective with a numerical aperture of NA=0.1 and laser pulse of 400fs duration with a energy of 3μJ generated by a Ti:sapphire amplifier. The sample could be translated parallel to the laser beam axis by a computer-controlled three-dimensional translation stage. We analyze its guided wave characterization. This one-step process provides a simple and flexible method for the fabrication of integrated optics components.
Darkening and micro-explosions inside ZBaF15 optical glass are investigated by using focused femtosecond laser pulse. With loose focusing, multiple micro-explosions occur in fused silica and ZBaF15 optical glass with single femtosecond pulse. The micro-explosions driven in the center of darkening region are observed in ZBaF15 optical glass. A numerical simulation is given by a model based on the beam propagation in wave-guide channeling induced by the front of excitation pulse. The mechanism of refractive index modification, which induced by femtosecond pulse, is discussed.
A new and more-flexible and directly femtosecond laser writing technique for the fabrication of waveguides has been demonstrated. By using this avenue, waveguides of 5mm are produced, and their characters are discussed. At the same time, the two writing manners are compared and the related physical mechanisms are summarized in detail.
The Fractional Fourier transform (FRT) is shown to be of potential use in the Optical Information processing. The effects of displacement and inclination in space domain on the intensity distribution in fractional Fourier transformation domain are studied. It is shown that the translation and rotation information can be separated simultaneously by experiment. The experiment setup has been built based on the principle proposed in this paper. Experimental results demonstrate that this method is feasible.
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