At present, the commonly used complex amplitude modulation method of light field is mainly realized by diffraction effect, which results in low energy utilization efficiency. Therefore, based on the phase-only spatial light modulator (SLM) and checkerboard phase lattice method, the generation of high-order Bessel vortex beam at zeroth-order of diffraction is realized. First, the basic principles of the Nyquist grating and checkerboard phase lattice method are introduced, the complex amplitude modulation method for generation of Bessel vortex beam at zeroth-order of diffraction is derived, and the corresponding hologram is coded. The light field distributions of low-order and high-order Bessel vortex beams generated by this method are simulated respectively. Then, the corresponding experimental optical paths are built based on the phase-only SLM, and the low-order and high-order Bessel vortex beams are prepared respectively. Finally, the advantages and disadvantages of this method are discussed. The experimental results show that the mode purity of the high-order Bessel vortex beam generated by this method is not as good as that of the first-order diffraction, but the diffraction efficiency can be increased by about 4.5 times.

As a new type of waveguide coupling element, the liquid crystal polarization volume grating has attracted much attention because of its wide angular response bandwidth and unique polarization characteristics. However, the current research on liquid crystal polarization volume gratings is still in the initial stage, and the waveguide display system based on liquid crystal polarization volume gratings has the disadvantage of small pupil range. A liquid crystal polarization volume grating with a central wavelength of 532 nm and a reflection diffraction angle of 50° at vertical incidence is fabricated. The peak diffraction efficiency of the grating reaches 75%. Using it as the coupling element of the waveguide display system, the image transmission and display can be realized. At the same time, the expansion of the exit pupil in one-dimensional and two-dimensional directions is designed and realized, and the exit pupil is expanded to the range of 14 mm×12 mm.

In order to realize the selective and accurate detection of H2O2 concentration, a fiber-optic evanescent wave biosensor based on horseradish peroxidase (HRP) is developed. First, the ultraviolet resistant quartz fiber with partial core removal is hydroxylated with sodium hydroxide solution and silanized with 3-aminopropyl triethoxysilane, then the fiber is immersed in glutaraldehyde solution for aldehyde cross-linked, and the fiber is moved into HRP solution with selective catalysis for H2O2 to fix HRP molecules. Finally, the fiber with HRP is dried at room temperature. The optical fiber biosensor immobilized on HRP can be obtained. The effects of the concentration and fixed time of glutaraldehyde and HRP and the temperature of H2O2 solution on the sensitivity of the sensor are studied experimentally. The response time, selection sensitivity, and detection limit of the sensor are tested, and the theoretical model of the sensor is established. The results show that the sensor has a high selective sensitivity to H2O2, and the output signal of the sensor has a linear relationship with the concentration of H2O2 in the range of 4--20 μmol·L -1, the sensitivity is -8.164×10 -4 μmol -1·L, the relative error is 7.59%, and the detection limit is 4 μmol·L -1.

A humidity sensor with a multimode fiber-air cavity-multimode fiber-polyvinyl alcohol (PVA) film structure based on Fabry-Perot interference is proposed. The influence of the curvature of air cavity reflecting surface on the light propagation and reflection spectrum is studied, and a method to increase the radius of reflecting surface by arc discharge is proposed. The experimental results show that the proposed method reduces the interference loss of light in the fiber core, allows more light to participate in interference, and improves the contrast and fineness of interference fringes. A layer of PVA film with a thickness of 14 μm is coated on the optimized multi-cavity end surface. The average sensitivity of the sensor can reach 73.24 pm/% when the relative humidity of the environment is 29.1%--81.8%, and has good time stability.

In order to solve the problem that super-resolution reconstruction of multi-spectral remote sensing images is susceptible to noise and chromatic aberration, a dark channel and cross channel based multi-prior combined multi-spectral super-resolution algorithm is proposed. First, dark channel prior and cross channel prior are introduced on the basis of traditional total variational prior. Then, based on the maximum posterior probability estimation theory, a multi-spectral super-resolution reconstruction algorithm with multi-prior combination is established. The proposed algorithm can achieve image edge information restoration, image texture information restoration, noise suppression, step effect suppression and chromatic aberration suppression, which can comprehensively improve the quality of reconstructed images. Finally, the experimental verification is carried out, and the results show that the reconstruction effect of the proposed algorithm is significantly improved compared with the existing algorithms under different signal-to-noise ratios (10--40 dB) and chromatic aberrations.

In order to reduce the polarization sensitivity of a spectrometer, a method of designing a depolarizer in convergent optical path is proposed. In this method, the telescope and collimator of the system are regarded as auxiliary optical paths, so that the polarization state of the beam can be expressed by Stocks vectors; then the polarization characteristic of the element is represented by Mueller matrix, and the polarization sensitivity model of the system based on Mueller matrix is derived; finally, multiple regression analysis is used to improve the calculation speed and accuracy of Mueller matrix. Based on this method, an improved depolarizer placed in the convergent optical path is designed. The polarization sensitivity of the system is less than 1%, and the image point splitting distance is less than 8 μm. The results meet the design requirements and verify the effectiveness of the method for designing the depolarizer in the convergent optical path.

The influence of out-of-band leakage on the measurement of ultraviolet (UV) band by traditional filter radiometer is serious. The solar blind phototube is used as the detection unit of the UV filter radiometer, the system-level relative spectral flux responsivity of each channel of the solar blind UV filter radiometer is measured by the built comparison measurement device, and then the absolute spectral irradiance responsivity of the UV filter radiometer is calibrated by using the irradiance standard lamp traced to the Nation Institute of Metrology, China (NIM). The monochromator system is used to complete the comparison between the UV filter radiometer and the standard detector traced to National Institute of Standards and Technology (NIST), and the maximum difference between the two results is 2.09%, which verifies the accuracy of radiation standard transfer. Finally, through the construction of solid angle, the 232--400 nm radiation standard is transferred to the UV integrating sphere radiation source with large aperture and large dynamic range.

A laser feedback interferometer for two-dimensional dynamic displacement measurement based on frequency division multiplexing technique is proposed. The output beam of laser is divided into two channels, which incident to the grating at ±1st-order auto-collimation diffraction angles respectively, and then return to the cavity along the original optical path to generate laser feedback interference. Eelectro-optic crystals are placed at ±1st-order diffractive optical paths to produce high frequency phase modulation. Two-dimensional dynamic displacement measurement can be realized by using frequency division multiplexing technique. The experimental results show that the proposed method can reconstruct the two-dimensional dynamic displacement of the object, and the displacement resolution can reach the order of 10 nm. By introducing a diffraction grating into the laser feedback interferometer, the proposed scheme not only improves the stability and anti-environmental interference ability of laser feedback interference measurement system, but also provides a new idea for multi-dimensional micro-displacement measurement using single light source.

According to the real height measurement of defects on the surface of microspheres such as capsules in laser inertial confinement fusion (ICF) experiments, a null microscopy interferometric measurement method based on vertical scanning white light interferometry is proposed to solve the problem of missing integer multiples of phase 2π at the defect jumps in existing measurement methods. The method adopts the concept of white light spherical null interferometric microscopy, and obtains the full field of view white light interferograms through vertical scanning spherical interference. Then, the seven-step phase-shifting algorithm and the bat-wing correction algorithm are used to calculate the surface defect morphology of ICF capsules. Finally, the white light interferometry is compared with the laser interferometry through experiments and the results show that the white light interferometry can effectively solve the problem of missing integer multiples of phase 2π at the defect jumps, realize the real height measurement of the ICF capsule surface defects, and extend the measurement range of microsphere surface defects.

In vivo and non-invasive human corneal elasticity measurement is clinically essential, but there is no gold-standard yet. An optical coherence elastography (OCE) method is provided for tissue natural frequency characterization. A microliter (10--40 Pa) air-pulse stimulator is used to induce tissue displacements with the magnitudes ranging from sub-nanometer to micrometer, and a high-resolution optical coherence tomography (OCT) system is used to quantify the resulting tissue dynamics. Both of a temporal relaxation model (R-Model) and a single degree of freedom Voigt model (SDOF-Model) are applied for natural frequency measurements on agar phantoms with concentration (mass fraction) of 1.0%--2.0% as well as on in vivo corneas of two human subjects. The measurement results show that the natural frequency remains the same as the stimulation force is increased from 10 Pa to 40 Pa, and is positively correlated to the square root of Young’s modulus (Pearson’s correlation coefficient is r≥0.98). The SDOF-model is more precise and repeatable. The average coefficients of vitiation (CVs) are only 0.9% for agar phantoms and 1.7% for human corneas using the SDOF-Model, while the average CVs are 8.4% for agar phantoms and 42.6% for human corneas using the R-Model. Compared to the R-Model, the combination of the SDOF-Model with micro-force OCE system is more suitable for in vivo human corneal biomechanics characterization.

Determining the orientation of electric dipoles in Q-switched crystals with anisotropic and nonlinear absorption properties is an important condition for measuring their absorption cross sections. Through the analysis of the space group to which the Co 2+∶MgAl2O4 crystal belongs and the position symmetry of the doped Co 2+ in the cell structure, it is determined that the transition direction of the electric dipole in the crystal is mainly distributed along the diagonal direction of four individuals in the cell, and the theoretical model of polarized incident light propagation in the Co 2+∶MgAl2O4 crystal is established. The nonlinear transmittance curve of Co 2+∶MgAl2O4 crystal cut along [100] direction is measured experimentally in the direction of polarized incident light. The experimental results are fitted by the established model. The ground state absorption cross section and excited state absorption cross section of Co 2+∶MgAl2O4 crystal in 1.5 μm wave band are (3.6±0.3)×10 -19 cm 2 and (4.5±0.4)×10 -20 cm 2, respectively.

We propose a method to realize the pulsed operation of all-fiber mid-infrared lasers. The absorption cross-section of dysprosium (Dy 3+) ions is overlapped with the emission cross-section of erbium (Er 3+) ions in fluoride glass in the 2.8 μm wavelength region. On this basis, a piece of Dy 3+-doped fluoride fiber is used as a fiber saturable absorber to achieve passively Q-switched pulsed operation at 2.8 μm in the all-fiber structure of an Er 3+-doped fluoride fiber laser. Furthermore, a pair of fiber gratings with a central wavelength of 3.1 μm are placed at both ends of the saturable absorber to solve the problem of passively Q-switching failure caused by the absorption saturation of Dy 3+ ions under high pump power due to the long lifetime of the upper energy level of Dy 3+ ions. A rate equation model for this 2.8 μm passively Q-switched Er 3+-doped fiber laser is built in view of this structure. The effects of the saturable absorber parameters and the resonator feedback conditions on the pulsed operation power and time characteristics of the 2.8 μm laser are evaluated. Numerical results indicate that the introduction of fiber gratings accelerates the recovery process of the saturable absorber, which is conducive to maintaining the Q-switched pulsed operation at high pump power.

Under the condition of high power laser operation, the quantum defect of rare earth ions and the intrinsic absorption of glass materials will lead to the overall increase and gradient distribution of the temperature of the gain fiber in the optical fiber amplifier. In the state of thermal equilibrium, the thermo-optic effect of optical fiber materials will induce the redistribution of transverse refractive index of optical fiber and cause the change of mode characteristics of gain fiber under the condition of high power laser operation. For this reason, the numerical calculation method of multi-physical field finite element modeling is used to systematically study the thermally induced mode characteristics of large mode field ytterbium doped quartz fiber under the condition of high power laser operation. The changes of mode characteristics of large mode field gain fiber under different laser operating power, gain fiber design parameters (core diameter, numerical aperture, thermo-optical coefficient) and fiber bending are analyzed and summarized. The results show that with the increase of laser power, the temperature difference between the core and the cladding will increase, which leads to the increase of the parameter V of the fiber, the decrease of the transmission loss coefficient of the mode and the increase of the power factor of the mode in the core region.

Large core diameter crystal waveguides can absorb higher power pump light and achieve higher output power. At the same time, the peak power density in the core layer is relatively low during mode-locking operation, and the accumulation of nonlinear effects is reduced. Based on this, a passively mode-locked picosecond laser based on Yb∶YAG large core diameter crystal square waveguide is constructed. In the experiment, firstly, the high mirror is used instead of the semiconductor saturable absorption mirror (SESAM), and the position and angle of the crystal waveguide are adjusted to match the pump light with the waveguide core layer under higher pump power. Then, the angle of the spherical mirror is carefully adjusted to couple the signal light into the waveguide core layer to minimize the loss in the cavity. The designed laser adopts a folded cavity structure, and achieves an average power of 10.2 W, pulse width of 65 ps, repetition rate of 30.15 MHz, and single pulse energy of 0.34 μJ without dispersion compensation device.

The line structured light galvanometer scanning system realizes three-dimensional profile measurement of the measured objects via swinging a mirror, which has the advantages of strong environmental adaptability, fast measurement speed and compact structure. To reduce the difficulty of system installation and improve the universality of calibration method, a calibration idea is proposed to directly establish the relationship between the coefficients of reflected laser plane equation and the swing angle of galvanometer. The general expressions of coefficients of the laser plane and the swing angle of the galvanometer are deduced and obtained by considering the relative position relationship between the components of the system. According to the coefficients of the laser plane equation obtained at the specific swing angles, the undetermined coefficients in the expressions are obtained by the least square method. The experimental results show that maximum relative height deviation of the steps measured by the measurement system calibrated by the proposed method is -0.3029%, and the multi-scale features of complex surface can also be acquired successfully.

In order to realize the accurate registration of cross-source point clouds with different measurement scales, resolutions, and accuracy, a measurement point cloud data registration method based on multi-scale sampling is proposed. The scale slip algorithm is used to filter out the high-frequency details, retain the contour data, and combine the voxel grid neighborhood method to realize the downsampling of point cloud data. For the low-resolution point cloud data measured by macro-structured light vision, through the progressive three-dimensional point cloud upsampling algorithm based on depth learning, the contour details of structured light point clouds can be accurately restored, and the unity of scale and resolution of cross-source point clouds can be realized. Finally, the iterative nearest point method is used to register the data with scale approximate after processing, and the registration relationship is inversely applied to the registration of the original cross-source point cloud. The experimental results show that the multi-scale sampling method can improve the registration accuracy of cross-source point clouds and can be effectively used for high-performance detection of engine blades and other parts.

In order to expand the field of view of the mirror binocular vision sensor, it is an effective scheme to replace planar mirror with spherical mirror. However, the reflection imaging with convex mirror will lead to the decline of image quality and sharpness, so the optical characteristics of binocular vision sensor for single camera mirror are studied. Taking the off-axis non-central spherical mirror as the research object, the imaging models with different optical characteristics are established. The effects of spherical mirror parameters on field range, resolution, and depth of field are quantitatively analyzed by simulation and experiment. The design method of double spherical mirror parameters is given under the condition of industrial camera and optical lens parameters. A vision sensor based on single camera and double spherical mirror is constructed, which can realize mirror binocular vision imaging. By analyzing the optical characteristics of the vision sensor based on spherical mirror reflection, it provides a basis for the design of a new mirror binocular vision sensor.

Low-dimensional black phosphorus materials, such as two-dimensional black phosphorus (2D-BP) and black phosphorus quantum dots (BP-QDs), show great potential application value in structural and photoelectric properties. However, they are still faced with problems including uncontrollable synthesis and poor antioxidation performance. In this research, the simple and low-cost synthesis of low-dimensional black phosphorus was achieved by the microwave method. The effects of microwave annealing temperature and annealing time on the structure, morphology, and photoluminescent properties of such black phosphorus were studied. An aluminium oxide (Al2O3) protective layer was deposited on the surface of BP-QDs samples through atomic layer deposition, and the influence of Al2O3 film thickness on the antioxidation performance of BP-QDs was investigated. The results show that the size of the quantum dots gradually decreases as the microwave annealing temperature rises and the photoluminescence emission peak exhibits blue shift, which demonstrates that the reaction temperature affects the size of the material and then affects the band gap and photoluminescent properties of the material. The black phosphorous nanosheets are gradually peeled off to form BP-QDs as the microwave annealing time increases. The BP-QDs are uniformly distributed and smaller in size when the microwave annealing temperature and time are 250 ℃ and 4 h, respectively. In addition, a thicker Al2O3 film offers better protection. Specifically, BP-QDs present the optimal antioxidation performance in the atmosphere when the thickness of the Al2O3 film is 20 nm.

SiO2 nanospheres with different particle sizes are self-assembled on polyethylene substrate to form structural color films with different size microspheres. Then, photocurable epoxy resin mixed with rare earth doping strontium aluminate long afterglow material is added to the structural color film. The long afterglow pattern is formed by mask method, and the film is etched with sodium hydroxide solution to prepare a composite anti-counterfeiting film composed of long afterglow and structural color with high stability. The results show that the photonic band gap of the surface photonic crystal structure is used to match the fluorescence band of the bottom’s pattern, the fluorescent pattern at the bottom can be displayed by scraping or wetting. At the same time, the surface structure can be quickly restored by wiping with ethanol and the fluorescent pattern can be hidden again, this method can enable the anti-counterfeiting label to be reused in a rewritable way. In addition, the corroding and bending tests show that the prepared films have strong robustness.

Traumatic brain injury (TBI) caused by shock waves is one of the most common fatal and disabling diseases, and thus the early detection and classification of blast-induced TBI (bTBI) have important clinical significance. In this paper, based on the continuous terahertz wave imaging system, the brain tissues of rats with different degrees of bTBI are detected by the continuous-wave terahertz attenuated total reflection (CW THz-ATR) imaging system, and the THz images of these brain tissues of different levels of trauma are classified and identified by the support vector machine (SVM). The imaging results show that the detection of brain tissues with mild and moderate bTBI can be realized by the THz-ATR imaging technology. Moreover, the identification and classification of THz images of different levels of trauma by SVM can achieve the accuracy of 86.36%. This suggests that THz imaging technology has great potential for the early and precise detection and diagnosis of different degrees of bTBI.

Oral squamous cell carcinoma (OSCC) has a high incidence and limited prognosis, and it is of great significance to improve the prognosis by early diagnosis and accurate identification of the lesion boundaries during surgery. Polarization-sensitive optical coherence tomography (PS-OCT) can not only obtain tissue microstructure information, but also obtain tissue polarization information, which can improve the specificity of tissue diagnosis. In order to verify the feasibility of PS-OCT technology in the diagnosis of OSCC, a self-developed high-resolution PS-OCT system is used to image OSCC tissue ex vivo. The preliminary imaging results show that OSCC has an obvious birefringence effect compared with the normal tissue, and the accumulative phase retardation can be used to distinguish normal tissues and cancerous tissues. Finally, it is proved that high-resolution PS-OCT technology has great potential for identification, diagnosis, and boundary detection of OSCC tissue. In addition, it can assist surgeons in disease screening and intraoperative boundary detection.

Second harmonic generation (SHG) imaging technology is a powerful tool capable of imaging non-centrosymmetric biological tissues without labeling, which has become an important means of life science research. Due to the diffraction limit, SHG technology cannot resolve the fine structures below the diffraction limit. Although super-resolution microscopy has made breakthrough progress, the coherent nonlinear process of SHG limits the development of the SHG super-resolution microscopy. A point-scanning structured illumination SHG super-resolution microscopy (SHG-psSIM) technology is proposed to realize the super-resolution SHG microscopic imaging of zinc oxide particles and mouse tail tendons. The electro-optic modulator is introduced into the excitation light path of the traditional SHG microscopy system. A point-scanning structured illumination pattern is generated by sinusoidally modulating of the excitation beam. Based on the moiré fringe effect generated by interaction of the point-scanning structured illumination pattern with the sample structures, the undetectable high frequency information of samples is moved to the observable passband of the microscopy and detected by the photomultiplier. Finally, the algorithm software is used to reconstruct the super-resolution image. Compared with the traditional SHG system, the resolution of SHG-psSIM is improved by 1.86 times.

Solar simulator is a key equipment in the research of photovoltaic and material degradation, which can provide stable and controllable characteristic irradiance spectrum for light immersion and durability testing. Based on the high-power single-crystal narrow-band small-emitting surface LED light source, a super-hemispherical homogeneous lens is used to collect light in full aperture, and the distributed optical structure of the curved surface is designed, so as to achieve efficient spectral matching on the target surface and irradiance of one solar constant (irradiance of 100 mW/cm 2). The experimental results show that the irradiance fluctuation of the solar simulator designed in this paper is less than 1.15% within 1000 h, the irradiance non-uniformity in the square area of 60 mm×60 mm in the center of the target surface is 1.98%, the irradiance non-uniformity in the 80 mm×80 mm region is 4.99%, and the spectral matching of light spot reaches class A. The system has compact structure and strong expansibility, and can be used for long-term steady-state measurement.

A critical pattern selection method for full-chip source and mask optimization based on depth-first search is proposed. The growth factor and projection boundary of mask spectra are used to describe the diffraction spectrum characteristics. The critical pattern selection method based on depth-first search is designed to realize the critical pattern selection for full-chip source and mask optimization, so as to obtain all critical pattern groups. Compared to existing methods of the same kind, the proposed method can obtain all critical pattern groups covering all frequency groups. Tachyon Tflex, one of the state-of-the-art commercial computational lithography software from Netherlands ASML company, is used to simulate and verify the proposed method. The results show that the process window obtained by the proposed method is better than that of the Tachyon Tflex method. The proposed method shows better results of selected critical patterns than the reported methods.

In optoelectronic applications or specialty lighting such as laser projection, structured light, and beam shaping, a non-imaging optical system is often required to achieve a specific light distribution design. For this purpose, a light distribution equation was established to describe the optical system. After the beam, the optical surface, and the target screen were discretized, the mapping relationship between the optical path length K of the sub-surface and the energy E at the target point was leveraged to obtain the corresponding light distribution equation under length-energy mapping. Although adjacent optical path lengths were subject to complex nonlinear competition in the length-energy mapping, K and E enjoyed a favorable monotonic mapping relationship that paved the way for introducing a deep neural network to fit the length-energy mapping. Then, deep learning was adopted to solve the light distribution equation as an inverse problem, and the required freeform optical surface was thereby obtained. With English letters and Arabic numerals in an input lattice of 28×28 as the training set, the design of optical surfaces with the corresponding character illumination distributions was achieved through multi-dimensional parameter adjustment and training of the three-layer neural network. The structural similarity of the optical simulation results reaches 99.97%, which indicates that the deep neural network can memorize (or store) the optical surfaces of each character by learning. This is equivalent to building an efficient and scalable intelligent optical character library. The basic light distribution equation established with complex media provides an elementary theoretical framework for existing light distribution methods and is conducive to the systematic expression of the theory of non-imaging optics.

To study the mode-locked matching accuracy of the Fourier domain mode-locked optoelectronic oscillator (FDML OEO), we analyze the starting process of the FDML OEO when the filter tuning period deviates from an integral multiple of the loop round-trip time. We investigate the relationships among the FDML matching accuracy, the open-loop gain of FDML OEO, the half-wave bandwidth of the tunable filter, and the frequency-swept output bandwidth. Then, the phase noises in the beat frequency signal generated by delayed self-heterodyne (DSH) from the output linear sweep signal of FDML OEO are used to characterize the quality of the FDML OEO output signal. Experiments are conducted to verify the relationships among the half-wave bandwidth of the tunable filter in the FDML OEO, the open-loop gain of the system, and the FDML matching accuracy. The influence of the matching accuracy in the Fourier domain on the bandwidth of the radio-frequency FDML OEO output signal is experimentally analyzed. The experimental results are consistent with the theoretical ones. Specifically, a larger half-wave bandwidth of the tunable filter and a higher open-loop gain correspond to a lower requirement for FDML matching accuracy; in contrast, a larger frequency range of the FDML output results in higher matching accuracy required. A more serious detuning indicates a smaller maximum frequency sweep range that can be achieved by the FDML OEO. The research results provide significant technical and theoretical support for the development of the broadband FDML OEO with low phase noise.

This paper investigates the multiple electromagnetically-induced transparency-like (EIT-like) effects of the ipsilateral, opposite-side, and antisymmetric double loop-stub (LS) resonator side-coupled waveguides. By the finite element method, numerical simulation is conducted on the optical transmission properties of the three waveguides. The results show that the transmission spectrum, magnetic field distribution, and dispersion of the three waveguides strongly depend on structure parameters. Moreover, this paper puts emphasis on the study of the influence of the distance between two adjacent stub resonators or the distance between two horizontal branches of double LS resonators on transmission properties. When the distance decreases, the coupling between two LS resonators gradually increases, and more transmission peaks and dips (i.e., the stop bands) are observed, which indicates that the multiple EIT-like effects are significantly enhanced. In addition, in the case of the ipsilateral waveguide, when the distance between the two stub resonators is zero, the effects of the vertical branch width, horizontal branch width, and total horizontal branch length on the transmission spectrum are discussed. These side-coupled metal nanowaveguides have potential applications in future integrated optics, such as filters, sensors, and slow light devices.

Most of the researches on the bidirectional reflection distribution function (BRDF) are focused on the model establishment and application. The geometric attenuation factor (GAF), which plays an important role in the model, is based on the existing model. However, there are some limitations in the existing model, such as turning point, inability to keep bounded, and imperfect consideration in practical application. Based on the detailed analysis of the random surface model, a modified integral GAF is put forward, and the simulation is conducted to verify that the model can eliminate the bad behavior of BRDF when the reflection angle is large and keep the bounds within the range specified by GAF. The data obtained by the proposed model fit the existing BRDF data better through simulation, and this model explains the backward reflection phenomenon effectively.

In this paper, the composite micro-nano structure surface of Al2O3-Si with a low ratio of depth to width and full duty ratio was prepared on the monocrystalline silicon substrate by using the self-assembly mask etch technology as well as the conformal growth feature of atomic layer deposition technology. The results of spectral reflectance tests show that when the bottom attains the full duty ratio and the ratio of depth to width is close to 1∶1, the average reflectance of the composite micro-nano structure surface in the frequency band of 3--5 μm is less than 3.5% at an incident angle of 8°. The results of nano-indentation tests demonstrate that the elastic recovery rate of the composite micro-nano structure surface of Al2O3-Si is 10.14% higher than that of single silicon substrates, which proves that the deposited alumina film can improve the mechanical properties of the anti-reflection micro-nano structure.

In order to improve the film thickness uniformity of the meniscus lens surface, the film thickness uniformity of the meniscus lens surface in the third-order common rotation planetary system is studied. The motion trajectory equation of the third-order common rotation planetary disk is constructed. According to the film thickness calculation formula, the relative film thickness distribution model of meniscus lens surface is established which is related to the dip and revolution radius of the third-order disk. The distribution model is verified experimentally by electron beam evaporation and ion beam assisted deposition. In addition, the structural parameters of the third-order common rotation planetary system are optimized according to the multi-experimental results to improve the film thickness uniformity of the meniscus lens surface. The experimental results show that when the rotation radius is 650 mm and dip is 60°, the film thickness uniformity of the convex surface of the meniscus lens can be controlled within ±2.45% without using the correction bezel technology.

SixNy is often used as the suppression material of quantum well intermixing (QWI). In order to explore the effect of SixNy growth process on the intermixing effect of InGaAs/GaAs quantum well structure, a series of experiments are carried out on the process parameters of plasma enhanced chemical vapor deposition (PECVD) method, such as deposition time, SiH4 flow rate, and radio frequency (RF) power. The experimental results show that SixNy can protect the quantum well well, but its thickness has little effect on the inhibition effect of QWI. When the SiH4 flow rate is large, Si is rich in SixNy, and Si may diffuse during annealing to form electrical compensation with P-type ohmic contact layer, and at the same time induce quantum well intermixing, resulting in a large blue shift of its wavelength. With the decreases of SiH4 flow rate, the content of Si in SixNy decreases, and the refractive index decreases, but the blue shift is still large. In a certain range, the blue shift increases with the increase of RF power, and when the RF power is 50 W and the SiH4 flow rate is 50 sccm, SixNy plays a better in quantum well protection, and the blue shift is only 14.1 nm.