This paper proposes a self-supervised polarization image dehazing method with an angle-of-polarization (AoP) frequency-domain prior for strong scattering dense-haze scenarios. The method formulates dehazing as the recovery of the clear object-radiance polarization field, rather than only restoring a haze-free intensity image. By analyzing real polarized hazy images, we observe that atmospheric AoP is dominated by low-frequency components, while object-radiance AoP contains richer local variations. Based on this observation, an AoP frequency-domain prior is incorporated into the polarization scattering model to guide the separation of object radiance and atmospheric polarization. A two-stage self-supervised training framework is then developed, where physical priors and the AoP prior provide stable component estimates, followed by joint optimization through scattering reconstruction consistency. In the object-radiance branch, a spatial-frequency dual-domain enhancement module is designed to capture both global haze degradation and local structural details. Experiments on a self-collected real short-wave infrared polarized hazy image dataset demonstrate that the proposed method achieves better target visibility, structural restoration, and quantitative performance than existing methods under dense-haze and strong scattering conditions.

Objective Fizeau interferometers, due to their common optical path structure, can effectively suppress systematic errors and improve the measurement accuracy of the instrument, thus being widely used as a powerful, efficient, and precise measurement tool in high-precision measurement. However, Fizeau interferometry requires an accurate phase shifting process to ensure phase retrieval accuracy, making it highly susceptible to time-varying factors such as mechanical vibrations in industrial environments and airflow disturbances in large-aperture interferometers. In addition, since the reference light and test light in Fizeau interferometers are difficult to be separated for independent control, the characteristic of the common optical path structure has become a major limitation for its realization of dynamic measurement. Therefore, achieving dynamic Fizeau interferometry remains a significant challenge in the field of optical interferometry. To address this issue, various solutions have been proposed in the past decade, including software algorithms and innovative optical path model schemes. Among them, schemes based on software algorithms offer good flexibility and are not limited by optical hardware and structures, but they struggle to solve the problems of demodulation of quasi-zero fringe interferograms and airflow disturbances. Innovative optical model schemes include spatial phase shifting synchronous interferometry and dual-channel temporal phase shifting interferometry. The spatial phase shifting interferometry scheme can realize dynamic interferometry but suffers from the issue of non-common path error. The dual-channel temporal phase shifting synchronous interferometry achieves vibration-resistant measurement through an additional vibration detection channel, thereby improving measurement accuracy, but it cannot cope with airflow disturbances. Therefore, it remains challenging to solve the effects of vibrations and airflow disturbances while maintaining common-path characteristics in Fizeau interfometry. To address this problem, we propose a dynamic Fizeau interferometry based on Chirp-Fourier demodulation of circular fringes, offering a novel solution for high-precision dynamic measurement using Fizeau interferometry under conditions of vibration and airflow disturbance. Methods The dynamic Fizeau interferometry based on Chirp-Fourier demodulation of circular fringes is proposed, which can be used for high-precision dynamic measurement under vibration and airflow disturbance. The optical path of this method consists of a main channel with Fizeau interference and an assistant channel with circular carrier-frequency interference. The main channel adopts an on-axis Fizeau interference path to ensure that the reference beam and the test beam are strictly in a common path; the assistant channel uses an assistant defocused source to generate circular fringe interferograms, which are used to detect real-time dynamic disturbances, thereby assisting the main channel in realizing dynamic measurement. In the process of reconstructing the tested phase, the Chirp-Fourier demodulation algorithm of circular fringes is firstly used to perform Chirp-Fourier transform on the fringes of the assistant channel, obtaining an energy-concentrated single-peak spectrum. Then, a Gaussian window is used to extract this peak and perform inverse Fourier transform to obtain the disturbance phase of each frame. Subsequently, the phases are subtracted from that of the first frame to obtain the dynamic disturbance phase of the interferometer. Finally, by combining this disturbance phase with the quasi-zero fringe interferogram of the main channel, we can accurately reconstruct the tested phase using the least squares algorithm. Results and Discussions Comparative measurement experiments were conducted in a vibration environment, and the tested phase was obtained using the proposed method and the MPSI method, respectively. The results show that although the MPSI methods have a certain vibration-resistant capability, they struggle to handle quasi-zero fringe interferograms with random tilt phase shifts, thus still exhibiting significant ripple errors. In contrast, the proposed method shows high consistency with the reference phase, with the PV (peak to valley) and RMS (root mean square) of their residuals being only 0.0193 lambda and 0.0019 lambda, respectively. Meanwhile, through 6 sets of measurement experiments, the repeatability precisions of the proposed method in terms of PV and RMS are 7.8 & times;10(-3)lambda and 6.5 & times;10(-4)lambda, respectively. In addition, dynamic measurement experiments were carried out under airflow disturbance conditions. The PV and RMS of the residuals between the obtained results and the static reference phase are 0.0402 lambda and 0.0059 lambda, respectively. The repeatability precisions of PV and RMS obtained from 6 sets of dynamic measurements are 1.1 & times;10(-2)lambda and 9.2 & times;10(-4)lambda, respectively. The results indicate that the proposed method can effectively solve the measurement problems caused by vibration and airflow disturbance under quasi-zero fringe conditions, with high measurement accuracy and repeatability. It can be seen from the above measurement results that the measurement accuracy under airflow disturbance is lower than that of the vibration measurement experiment. The main reason is that the airflow disturbance in this experiment is generated by an air gun, which cannot ensure the randomness of the airflow disturbance. It is difficult to fully suppress the airflow disturbance through the sum and average of multiple sets of phases, resulting in random errors remaining in the final phase map. Conclusions This study proposes a dynamic Fizeau interferometry based on Chirp-Fourier demodulation of circular fringes, aiming to provide a simple and high-precision dynamic phase measurement solution for Fizeau interferometers. This method introduces an assistant channel with circular carrier-frequency interference into the traditional Fizeau interferometric optical path through an assistant defocused point source, and uses the proposed Chirp-Fourier demodulation algorithm of circular fringes to retrieve the disturbance phase from this channel. By combining the disturbance phase with the quasi-zero fringe interferograms of the main channel, high-precision reconstruction of the tested phase can be achieved. It not only maintains the high-precision measurement advantages of Fizeau common-path structure but also solves the phase retrieval problem under airflow disturbance in asynchronous phase-shifting interferometry. Meanwhile, it provides a new solution for single-frame phase demodulation of circular fringe interferograms. The results of numerical simulations, vibration-resistant measurements, and airflow disturbance measurement experiments verify the feasibility of the proposed method under quasi-zero fringe conditions and in the presence of environmental dynamic disturbances. The PV measurement errors under vibration and airflow disturbance conditions are 0. 0193 lambda and 0.0402 lambda, respectively, and the PV repeatability precisions are 7.8 & times;10(-3)lambda and 1.1 & times;10(-2)lambda, respectively. These results indicate that the proposed method can achieve high-precision dynamic measurement and has the advantages of a simple structure and low hardware cost. It is expected to become an efficient and universal solution for in-situ measurement applications.

Optical throughput and spectral resolution are two critical parameters for achieving rapid and accurate Raman microscopic imaging. However, conventional methods often face a trade-off between these two performances. In response to this limitation, this work proposes a high-efficiency Raman microscopic imaging system based on a dispersion-interference hybrid spectroscopic architecture. By integrating Amici prisms into a Sagnac interferometer, the system enables spectral shearing control without the need for an entrance slit, achieving both high throughput and good spectral resolution. Using a 785 nm laser, the system was evaluated on Nd: Y3Al5O12ce-ramics, fluorite crystals, and SERS-enhanced 4-aminothiophenol samples on a gold substrate, achieving a point spectral resolution of 10 cm-1 and a full width at half maximum (FWHM) resolution of 25 cm-1. Combined with a 1024 x 1024 pixel EMCCD camera, the system supports area imaging and employs a one-dimensional push-broom scanning strategy to efficiently acquire the entire field of view, significantly improving imaging speed compared to conventional point-by-point scanning methods. Experimental results demonstrate that the system offers high throughput, high resolution, and rapid Raman hyperspectral imaging capabilities, with potential applications in material analysis, biological detection, and chemical imaging.

Phase-shifting interferometry with finite bandwidth light sources is a key technique for high-precision measurement of ultra-smooth optical components. However, influenced by vibrations, moving devices, and spectral bandwidth, the interference fringes exhibit not only random phase-shifting errors but also intra- and inter-frame nonlinear and non-uniform variations in modulation amplitude, which degrades the phase retrieval accuracy of existing random phase-shifting algorithms. To solve this problem, we propose a spatiotemporally decoupled iterative algorithm (SDIA). This method decouples the spatiotemporally varying modulation amplitude via multi-order Taylor expansion, stepwise separating the time-dependent and space-dependent variables in two distinct iterative steps to construct linear equations without variable coupling, thereby achieving high-precision phase retrieval via the least-squares alternating iteration. Simulations and experiments validated the feasibility and high accuracy of the proposed algorithm. The experimental results demonstrate that, for randomly phase-shifted interferograms under 40 nm bandwidth illumination, the retrieval residual errors of a planar smooth mirror are below 1 nm (PV) and 0.1 nm (RMS), respectively. To the best of our knowledge, this is the first time that such a spatiotemporal decoupling iterative algorithm using multi-order Taylor expansion has been proposed, which can address both random phase-shifting errors and spatiotemporally coupled modulation variations under finite bandwidth illumination conditions.

Freeform gradient-index (F-GRIN) media offer significant degrees of freedom for the design of advanced imaging systems. As manufacturing capabilities evolve toward complex refractive index distributions, a unified representation is increasingly required. In this paper, rotation-invariant orthogonal polynomials in the unit ball (ROPB) are proposed to provide a canonical 3D representation for F-GRIN. ROPB integrates spatial coordinates through rotation-invariant base functions, ensuring orthogonality and continuity in the unit ball. The index distribution and aberration properties of ROPB terms are analyzed to facilitate their application in optical design. Furthermore, the efficacy of ROPB is validated through the performance enhancement of an ultrashort throw ratio projection system. The results demonstrate that the ROPB can not only effectively guide the optical design of F-GRIN systems but also mitigates aberrations in non-rotationally symmetric systems, providing a feasible solution for the more compact and high-performance optical design.

Multispectral polarization imaging technology holds significance in various fields. This study proposes a multispectral polarization imaging scheme based on a narrowband reflection filter array (RFA), incorporating spatial dispersion that leverages the RFA to segment optical paths for multispectral image acquisition. The RFA was analyzed and designed, and a snapshot multispectral polarization imager was constructed. The feasibility of the spatial dispersion structure was experimentally validated. The proposed method can capture spectral polarization images at video frame rates with relatively consistent imaging quality across different bands and high spatial resolution, providing, to our knowledge, a new technical approach for realizing real-time multispectral polarization imagers.

This study presents a general vibration-resistant white-light interferometry (VWLI) for high-precision topography measurements in complex vibration environments. It employs an extended laser source in the laser interference channel to avoid reference mirror obscuration in the Mirau objective and uses an auxiliary compound interferometric cavity to establish a spatial phase-shifting interference path for instantaneous vibration detection, thereby achieving topography reconstruction in combination with the white-light interference channel. To validate the performance of the proposed method, comparative experiments were conducted in an environment with a vibration frequency ranging from 0 to 50 Hz and an amplitude of approximately 0.5 μm, yielding measurement deviations of less than 0.02% for the height and 0.74 nm for the roughness, respectively.

Objective In the precision polishing stage of optical element processing, optical interference detection methods are often employed to detect the surface shape and transmitted wavefront. Among them, the shearing interference method is a measurement technology that adopts its light wave and copied light wave, and there is a dislocation between the light wave and copied light wave in space, which makes it unnecessary to introduce the reference light wave. At present, the synchronous phase-shifting technology is the interference measurement method with the best anti-vibration effect. It can obtain multiple phase-shifting interferograms spontaneously, and then adopt the phase-shifting algorithm to restore the wavefront information to be measured. The combination of shearing interferometry and synchronous phase-shifting technology can realize the absolute common optical path phase-shifting measurement of the phase to be measured and remove the influence of environmental vibration and air disturbance on the interferometry. The study of synchronous phase-shifting shearing interferometry is significant for detecting transmission wavefront pairs and the surface shape of optical elements. In the wavefront measurement, due to the influence of the surface error of the reference mirror, insufficient utilization of light energy, environmental vibration, and air disturbance on the interference measurement results, we propose a synchronous phase-shifting shearing interferometry method based on polarization grating splitting. This can achieve high-precision detection of transmission wavefront and reflection wavefront. Methods The proposed method is based on polarization grating beam splitting to achieve the wavefront test method of synchronous phase-shifting shearing interference, which can be utilized to test the transmission wavefront. The shearing module is a reflective transverse shearing structure composed of a polarization grating, a plane mirror, and a quarter wave plate. The polarization grating is a diffractive optical element that realizes selective beam splitting based on the polarization state of the incident light. The beams carrying the wavefront to be measured are divided into two orthogonal circularly polarized beams by the polarization grating, and then transverse shearing occurs again after being reflected by the plane mirror via the polarization grating. The orthogonal polarized light with certain transverse shear is formed after passing through a quarter wave plate. The phase-shifting module adopts a synchronous phase-shifting structure composed of a two-dimensional phase grating, a small aperture diaphragm, and a phase delay array. The orthogonal linearly polarized light is diffracted by the two-dimensional phase grating, and the diffracted light of (+/- 1, +/- 1) order is selected by the small aperture diaphragm. Then the phase shifting is generated by the phase delay array, and the interference occurs after passing through the linear polarizer. The vertical phase-shifting shearing interferogram can be obtained by rotating the polarization grating. Meanwhile, via adopting the transformation of the test scheme, the surface wavefront generation module of the optical element is added in front of the shear module, which can detect the surface shape of the optical element. For the shearing interference fringes in x and y directions collected by CCD, the image registration algorithm based on phase correlation, the four-step phase-shifting algorithm, and the phase unwrapping algorithm based on DCT are leveraged to obtain the phase distribution to be measured. Subsequently, the wavefront to be measured is reconstructed by the least square wavefront reconstruction algorithm based on differential Zernike polynomials. Results and Discussions We build a phase-shifting shearing interferometer based on polarization grating on the optical platform of the laboratory, and measure a lens with a diameter of 25. 4 mm and a focal length of 50 mm. The PV value of the wavefront to be measured is 0. 5366 lambda and the RMS value is 0. 1519 lambda (Fig. 7). The results are compared with the measured results of the SID4 wavefront sensor (Fig. 8), which proves the accuracy of this method. The repeatability experiment proves the stability of the measurement results of this method. Then, we construct a measuring device of optical element surface shape based on polarization grating synchronous phase-shifting shearing interferometry on the optical platform of the laboratory. A concave mirror with a diameter of 25. 4 mm and a focal length of 50 mm is measured. The PV value of the wavefront to be measured is 0. 6044 lambda and the RMS value is 0. 1669 lambda (Fig. 13). The comparison experiment with the measurement results of the SID4 wavefront sensor (Fig. 14) and the repeatability experiment are also carried out. This can verify the accuracy and stability of the measurement results of the synchronous phase-shifting shearing interferometry based on polarization grating. Conclusions A phase-shifting shearing interferometry based on polarization grating splitting is studied to detect the transmission wavefront and the surface shape of optical elements. The method employs a reflective shearing structure based on polarization grating splitting, with a compact and flexible optical configuration. Compared with traditional grating, the polarization grating has ultra-high diffraction efficiency, the energy of the two beams is uniform, and the light energy utilization is high. By combining shearing interference with synchronous phase-shifting technology, the quasi common path phase-shifting measurement of the wavefront to be measured is realized, which removes the influence of environmental vibration and air disturbance on the interferometry. The shearing interferograms in X and Y directions are processed by the image registration algorithm based on phase correlation, and the four-step phase-shifting algorithm and phase unwrapping algorithm based on DCT are adopted to obtain the shearing phase distribution. Then the wavefront to be measured is reconstructed by the least square wavefront reconstruction algorithm based on differential Zernike polynomials. The results show that the measurement results of this method are accurate and stable, and can achieve high-precision wavefront dynamic measurement, which is of significance for detecting the surface shape and transmission wavefront of optical elements.

Stitching interferometry is an essential technique for the non-contact, high-precision measurement of large apertures or complex optical surfaces. However, the accuracy of full-aperture surface reconstruction is significantly compromised by subaperture positioning and systematic errors. To address this challenge, this study introduces a novel stitching interferometry method utilizing alternating calibration of positioning and systematic errors (SIAC). This method calibrates one type of error while maintaining the other constant, and alternates between these processes to effectively decouple the two errors, facilitating accurate phase stitching. Within this calibration framework, an iterative weighted phase stitching model employing vertical projection for estimating overlapping areas was developed to calibrate positioning errors. Additionally, the rotation measurements of a single subaperture, in conjunction with a global fitting approach, were employed to correct reference errors. Numerical simulations have confirmed the efficacy of SIAC in calibrating these errors. Moreover, experimental measurements were performed on both a plane mirror and gullwing aspheres, with the resulting stitched full-aperture phase distributions and cross-testing outcomes affirming the method's accuracy and practicality. This research provides a novel solution for stitching interferometry, enhancing the precision of optical surface measurements.

Objective Laser inertial confinement nuclear fusion is significant for explosion simulation, astrophysics, and other research. Meanwhile, the target pellet as a fuel container in fusion requires extremely high precision in surface morphology, and since any small morphological defect on its surface may cause asymmetric compression and experimental failure, the measurement of target surface morphology is essential. However, during the actual measurement of the surface morphology of the target pellet, the measurement results are susceptible to vibration, such as ambient light changes and optical platform vibration, which will introduce random errors to cause inaccurate measurement results. Therefore, it is of practical significance to correct the random errors during the measurement and improve the vibration resistance of the target shot. The non-uniform fast Fourier transform (NUFFT) algorithm can correct non-uniform interference signals, which is characterized by high accuracy and low hardware cost. Thus, based on the NUFFT algorithm, we propose an anti-vibration white light interferometry method. Specifically, the white light interferometry optical path adopts dual imaging channels and the main channel collects the white light interferogram. The secondary channel collects the quasi-monochromatic optical interferogram, calculates the phase shift interval of the vibration according to the quasi-monochromatic light interferogram, and corrects the white light interference signals collected in the vibration environment according to the obtained phase-shifting interval combined with the NUFFT algorithm to obtain a more accurate white light interference signal. According to the corrected white light interference signal combined with the seven-step phase-shifting method, the three-dimensional topography information of the object to be measured is restored. Additionally, the algorithm can be adopted for correcting non-uniform interference signals with random phase shift interval in random vibration conditions. Methods First, the Fourier transform algorithm is employed to extract the phase information of the quasi-monochromatic light interference signal, and the phase information is expanded into continuous phases by unwrapping to obtain the non-uniform phase-shifting interval of each pixel position in the interferogram. Meanwhile, the non-uniform phase-shifting interval is sorted from small to large, and then the interferogram corresponding to the non-uniform phase-shifting interval is also sorted accordingly. The sampling interval is normalized and oversampled into uniform grid coordinates, and the NUFFT algorithm is utilized to convolute the sorted white light interference signal according to the phase-shifting interval after sorting. The convoluted interference signal is transformed by the Fourier transform, the influence of the Gaussian kernel function in the spectrum is removed, and the uniform interference signal is obtained by the inverse Fourier transform. Finally, the topographic distribution of the step surface is acquired by calculating the phase of the uniform interference signal and the peak position of the modulation system. Results and Discussions Figure 7 shows that in the vibration environment, the step surface morphology directly restored by the white light interferogram before correction has a large distortion, and its morphology information cannot be restored correctly. The average height measured in Table 1 is 0.1419 mu m, the relative error between the nominal value of 0.139 mu m and the step plate is 2.13%, and the restored step surface shape is close to the reference surface shape measured by the Veeco interferometer. In Table 1, the corrected peak-to-veally (PV) and root-mean-square (RMS) values of the corrected step surface are 0.2011 mu m, which are significantly higher than those of 0.3417 mu m and 0.0735 mu m before correction, and are close to the Veeco reference value. The results show that the surface shape of the step measured by this method is in good agreement with the actual measured surface shape, with high measurement accuracy. Conclusions A white light interferometry anti-vibration measurement method based on a non-uniform fast Fourier transform algorithm is studied to solve the problem of white light interferometry in a vibrating environment. We employ a dual-channel optical path system to calculate the actual phase-shifting interval by adopting the quasi-monochromatic optical interferogram collected by the secondary channel camera and correcting the white light interferogram collected by the main channel camera according to the obtained phase-shifting interferogram. The simulation and experimental measurement results show that the NUFFT algorithm can accurately correct the non-uniform white light interference signal, and the morphological information of the object to be measured can be well recovered from the corrected uniform white light interference signal. The results show that our method can restore the surface morphology of the measured object in the vibration environment.

Freeform gradient index (F-GRIN) media are increasingly used in optical systems. The existing ray tracing methods for F-GRIN have low calculation efficiency and require manual adjustment of step size, making the design process complex. To address this, we propose an adaptive ray tracing (ART) method for F-GRIN. ART obtains an initial step size based on an index directional derivative and the element's length. During the subsequent transmission process, the step size is adaptively adjusted. The accuracy and speed of ART were verified through multiple comparison tests. ART can reduce manual participation and significantly improve efficiency in the optical design of F-GRIN.

The growing interest in microprofile measurements for advanced semiconductor manufacturing and electronic glass screens has stimulated the demand for in situ dynamic white-light interferometry. However, it is challenging to perform vibration-insensitive measurements because of the broad-spectrum interference. In this article, we report a dual-wavelength phase-tilting iteration (DPTI) algorithm and local time-shifting (LTS) least squares algorithm for dual-channel dynamic white-light interferometry to extract the vibration information and recover the tested profile, respectively. The numerical simulations and comparative experiments were conducted and have shown high accuracy and reliability of the proposed method.

This study demonstrates a three-cavity multiplexing vibration-resistant Fizeau interferometry (TCM). The method injects a vibration-measurement pass (VMP), which utilizes three-cavity hybrid interference for the transmission of phase and vibration information, to the Fizeau phase-measurement pass (PMP). Moreover, the VMP is demultiplexed using the temporal difference of mixed fringes and synchronous phase-shifting phase extraction of difference fringe to obtain the vibration information, which is then used to calculate the measured phase combined with PMP. The feasibility and performance of the TCM are demonstrated experimentally. To the best of our knowledge, this is the first proposal of the TCM that not only solves the effect of vibration and null-fringe demodulation but also features a common path, simple testing process, and low system complexity.

To measure the defects on the inner and outer surfaces of a capsule,a null micro-interference capsule surface-defect measurement system based on white-light scanning interferometry is proposed.White-light interference technology is combined with Linnik micro-interference technology and an optical path-matching module is introduced to measure the different surfaces of different diameter capsules.Based on the concept of spherical null interference,a spherical surface is introduced as a reference surface to expand the measurement field-of-view.In actual measurements,piezoelectric ceramics are used to scan a capsule surface vertically,thus achieving a full-field white-light interference image.Phase-shifting and bat-wing correction algorithms are used to restore the morphology of the capsule surface.The proposed measurement method is built to measure the standard step plate,and the measured values are consistent with the nominal values,thus verifying the effectiveness of the measurement method.Subsequently,a capsule is measured.The results show that the proposed measurement method can accurately measure the distribution of defects on the inner and outer surfaces of the capsule.

Objective With the expanding application of large aperture and complex optical systems, the demand for aspheres is also increasing. Aspheres whose surface deviates from the spherical surface prove more design freedom for optical systems than spherical surfaces, and help improve image quality and achieve a compact and lightweight design of optical systems. Without high- precision testing, there cannot be deterministic control and manufacturing. The widespread utilization of aspheres requires high- precision surface measurement as support, and the final manufacturing accuracy is mainly determined by the testing accuracy. Asphere testing has developed numerous solutions, among which non-interference methods usually have sound flexibility without high measurement accuracy, and some methods are contact measurement, which can easily damage the device under test. Interferometric measurement methods include null and non- null interferometry, among which null interferometry has limitations in measuring the dynamic range and flexibility. Non- null interferometry lowers the high requirements for wavefront compensation, thereby improving the dynamic range and universality of measurement. The subaperture stitching interferometry is the most widely employed among non- null interferometry. The combination of subaperture stitching interferometry and partial compensation can achieve high- precision and flexible asphere testing. We propose an aspheric subaperture stitching interferometry with a single- wedge variable compensator to provide a new solution for high- precision testing of aspheres. Methods The proposed method is an aspheric subaperture stitching interferometry with a single-wedge variable compensator, which can be adopted for flexible asphere interferometry. The standard converging spherical wave emitted by the interferometer is modulated by an optical wedge to reach the subaperture of the tested asphere. The optical wedge can realize translation and rotation along the optical axis direction. The scanning system includes modules of subaperture scanning and component alignment. During measurement, the direction of the output beam is changed by altering the axial position of the optical wedge to complete radial scanning of the subaperture ring from the center to the edge and reduce the motion complexity of the scanning module. Meanwhile, the spherical wavefront after being modulated by optical wedges can compensate for fundamental aberrations such as astigmatism and coma of asphere subapertures. All subapertures of aspheres are collected by tilting and rotating the optical wedge around the axis. Reverse optimization reconstruction is utilized to correct system return error and projection distortion for all subaperture data. Afterwards, the stitching algorithm using alternating calibration is employed to reconstruct the phase distribution with the subaperture data after system error correction. Results and Discussions The stitching algorithm using alternating calibration is utilized to obtain the full-aperture phase of the tested asphere. The six-dimensional positioning error obtained by stitching is shown in Table 2. The measured low-frequency phase of the tested asphere is shown in Fig. 16(a), and the peak-valley (PV) value and root-mean-square (RMS) are 0.4283 lambda and 0.1070 lambda respectively. The residuals of the proposed method and LuphoScan 260 are shown in Fig. 16(c), and the PV and RMS are 0.1259 lambda and 0.0273 lambda respectively. The phase distribution and residual show that the proposed aspheric subaperture stitching interferometry with a single-wedge variable compensator can achieve measurement accuracy of approximately lambda/8 (PV) for aspheres. The distribution of residuals is close to coma, and this may be caused by the following three reasons. Firstly, when a single optical wedge for asphere compensation stitching interferomety is employed, the optical wedge mainly compensates for the astigmatism and coma of the off-axis subaperture. In actual testing, the processing and installation errors of the optical wedge can cause the aberration compensation of the subaperture to deviate from the ideal design testing state, resulting in measurement errors. Secondly, it is necessary to align the testing system and ensure that the motion of the test mirror controlled by the scanning system during subaperture scanning measurement conforms to the subaperture planning route. In this experiment, the test mirror may tilt in the vertical direction, which usually introduces coma in the test phase. Thirdly, there are residuals in the calibration of the system retrace error and projection distortion, which are coupled into the retrieves phase. These problems will be our focus in the future. Conclusions We propose an aspheric subaperture stitching interferometry with a single-wedge variable compensator, providing a new solution for high-precision and flexible asphere testing. This method employs a single optical wedge as a subaperture aberration compensator, and compensates for the basic astigmatism and coma of the off-axis subaperture by adjusting the tilt angle of the optical wedge. Meanwhile, adjusting the axial position of the optical wedge can also achieve subaperture scanning at different off-axis positions. Finally, the stitching algorithm is adopted to complete the full-aperture phase reconstruction. Additionally, we analyze the wavefront aberration modulation mechanism of the optical wedge and propose a complete alignment method for the optical wedge pose system. The experimental results show that the proposed method has good consistency with the point scanning results of the 3D profilometer, and the full-aperture testing residual is about lambda/8 (PV). This indicates that the proposed method can yield high-precision asphere compensation stitching interferometry, and has a simple and flexible compensation structure, thus improving the measurement ability of subaperture stitching interferometry.

A high-resolution imaging spectrometry system is presented to enhance spectral shear control in traditional interferometric spectrometers. The scheme integrates Amici prisms into a Sagnac interferometer to achieve mixed spectral splitting. Combining lateral and dispersion shear effects controls the optical path difference for different wavelengths, enabling high-resolution spectral information with fewer sampling points. The study analyzes the physical model, conducts theoretical research, and optimizes the optical characteristics of the system. Essential components are manufactured and assembled, and an experimental setup is constructed, yielding high-resolution spectral data cubes, verifying the effectiveness of the system in spectral acquisition.

A dual-shearing interferometer (DSI) for multimodal hyperspectral imaging is presented. Two orthogonally stacked pairs of coherent beams are generated by a pair of novel, to the best of our knowledge, birefringent lateral shearing splitters. Consequently, two sets of interferograms with full pixel resolution are captured alternately in a time sequence in the double Nyquist frequency mode. Modals of dual-field-of-view hyperspectral imaging and differential-polarization hyperspectral imaging are introduced, and verification experiments are performed. The feasibility of other modals is discussed. The proposed method can effectively improve the instrument's performance in terms of the field of view, polarization, spectral resolution, and spectral range.

InGaAsP photocathode surface affects the absorption, transport and escape of photons, and has a great influence on quantum efficiency. In order to study InGaAsP photocathode surface, the electronic structure, work function, formation energy, Mulliken population and optical properties of In0.87Ga0.13As0.25P0.75(001)β2(2×4) reconstruction surface were calculated from first principles. Results show that stabilized the In0.87Ga0.13As0.25P0.75(001)β2(2×4) surface is conducive to the escape of low-energy photoelectrons. The narrow bandgap and emerging energy levels of the reconstruction surface make the electron transition easier. Under the action of the dipole moment, the electrons transfer from inner layers to the surface during the surface formation process. By contrast to the bulk, the surface absorption coefficient and reflectivity considerably decrease, and the high-reflection range becomes narrower as the falling edge redshifts. On the contrary, the surface transmissivity increases, which is conducive for the photons passing through the surface into the bulk to excite more photoelectrons. Meanwhile, the higher absorption coefficient of surface in low-energy side is favorable for long-wave absorption. The dielectric function peaks of the surface move toward the low-energy side and peak values decrease.

We report and demonstrate full-Stokes imaging polarimetry via random retarder rotation (R3). The method adds an assistant imaging channel comprising a linear polarization array and light source to the classical full-Stokes imaging optical path. Further, an alternating iterative algorithm of the polarization information matrix is used to solve the rotation angle of the phase retarder to obtain the full-Stokes information of the imaging target. Theoretical analysis, numerical simulations, and comparative experiments are conducted to verify that the proposed method can achieve accurate full-Stokes imaging measurements via R3. To the best of our knowledge, this is the first time that a full-Stokes imaging method with high precision performance has been proposed that does not depend on accuracy of rotation angle.