In order to use Hartmann-Shack wavefront sensor testing lithography objective lens accurately, two-dimension insert polynomial is proposed to replace Zernike polynomial, which is the basic of modal wavefront reconstruction. The wavefront aberration of a lithography lens is simulated to be the under-test wavefront. The root-mean-square (RMS) value of the reconstruction error reaches 0.0609λ. The possibility of this method is proved. The accurate of reconstruction changes stablely by increase of polynomial fitting orders when the under-test wavefront is ideal spherical wavefront. By reconstructing sine wavefront, cosine wavefront, aspherical wavefront and normal wavefront which contains low order of spherical aberration, coma, astigmatism, field curvature and distortion aberrations, the accuracy of Zernike modal wavefront reconstruction and two-dimension insert modal wavefront reconstruction is compared. A more stable and accurate basic of modal wavefront reconstruction is obtained.

Aiming at the problem that the omnidirectional sea-wave spectrum of fractal sea-wave model cannot satisfy the positive power law when the spatial wave number is smaller than the fundamental wave number, one-dimensional (1D) sea-wave model is proposed by combining statistical sea model and normalized band-limited Weierstrass-Mandelbrot (WM) fractal sea model. With the proposed method, the closed form expression of the omnidirectional sea-wave spectrum is calculated, and the obtained omnidirectional sea-wave spectrum is in good agreement with the commonly used Pierson-Moscowitz (PM) spectrum. The electromagnetic scattering coefficient of the improved model based on two-scale method is derived. The angular distributions of the scattering coefficient of Longuet-Higgins model, classical fractal model and improved model are analyzed. Simulation shows that the difference among the three model′s scattering coefficients is caused by the large scale of sea-wave, which proves the validity of the model. The results are also validated by real data.

Drop size distribution (DSD) observed at the ground depends on complex microphysical processes that progressively transform ice or water clouds particles aloft into rain below. DSD reflects the physics of rain and is the fundamental property for radar rainfall remote sensing, because it rules the relationship between the radar reflectivity factor Z and rainfall rate R. To better understand the microphysics of the summer precipitation, DSD measurements collected with Parsivel disdrometer are carried out at Beijing Weather Observatory in July to August 2007. The DSD characteristics and the relations among the radar reflectivity factor Z, rainfall rate R and mass-weighted mean diameter Dm are investigated. Specific Z-R relationship is derived for the whole data set.

A band selectable amplified spontaneous emission (ASE) source of an erbium-doped fiber (EDF) which can operate in either the C- or the C+L-band region is proposed and demonstrated. The band selectable ASE source is realized using the backward feedback technique with a 1×2 optical switch in a bi-directional pumping configuration. The 25.9 mW C-band and 22.5 mW C+L-band ASE spectra are alternately obtained merely by controlling the state of the optical switch.

The traditional fiber distributed temperature sensor has the shortcoming of low precision and expensive equipments. New distributed temperature sensor based on stimulated Brillouin scattering (SBS) is designed by filling alcohol in photonic crystal fiber (PCF). Since the refractive index of alcohol varies with temperature, which results in the effective mode area of PCF varying with temperature, the output power of pulse in fiber varies with temperature. The coupled amplitude equations of SBS in optical fiber are solved numerically. And the relations between output power and temperature are obtained. The possibility of new sensing mechanism is proved. In order to achieve a precision of 1 ℃ for the new design, the dynamic range of power measurement equipment is only 40 dB, which is far less than that of frequency measurement equipment in traditional measurement system. Some influence factors in the new system are also analyzed.

In previous studies on recording the low-frequency holographic grating via the Mach-Zehnder interferometer, a detailed analysis of the width and contrast of the interference fringes has revealed their rules of variation. This paper focuses on the fringe orientations for recording by the Mach-Zehnder experiment. It is confirmed experimentally and theoretically that the direction slope of the interference fringe orientations k1 is dependent on that of the connection line of the point light source k2 of two interference light, with a relation of k1×k2=-1. This result provides a theoretical and experimental basis for recording the different fringe-orientation low-frequency holographic grating and their applications in precision measurements.

In order to process the wrapped phase map with strong noise and under-sampled area simultaneously, four kinds of phase unwrapping algorithms based on fast Fourier transform are studied in depth and the speed, accuracy and the range of applications are expounded. The effective of denoising and dealing with the under-sampled situations of four kinds of algorithms are verified by computer simulations and experimental demonstrations. The results demonstrate that when the data contain strong noises, the quartic Fourier transform algorithm is the best, the combination algorithm based on lateral shearing interferometry and Fourier transform is the worst. While the data have under-sampled areas, the combination algorithm based on lateral shearing interferometry and Fourier transform is the best, followed by the quartic Fourier transform algorithm. When the experimental data contain both noises and under-sampled areas, the quartic Fourier transform algorithm can obtain the highest-precision results.

Phase retrieval algorithm is widely used to eliminate the unwanted conjugate image for in-line digital holography. Compared with the phase retrieval algorithms based on single hologram, phase retrieval with images recorded at multiple distances could improve the precision and convergence speed apparently, especially for the reconstruction of two images. However, it is critical to optimize the recording distances for the two images to achieve high precision and the true value of the reconstructed images. We record a lot of digital holograms at axially different planes in experiment. After analyzing the normalized root-mean-square (NRMS) error of the data, we conclude that the algorithm is suitable for the distance between 130 mm and 160 mm. And the conclusion can also be made that the reconstructed image which has the highest precision is achieved when the object distance is 150 mm and the object distance interval is 2 mm for which the NRMS error is 0.0096.

Based on vectorial diffraction theory, optical imaging system with continuous phase optical pupil filter for radially polarized beam is investigated. A continuous phase filter with cosine function is proposed and a sharper focus of radially polarized beam is obtained. This kind of filter is optimized with Matlab optimization toolbox and the aim of optimization is to reduce the superresolution parameter G with the Strehl ratio S as a constraint. Some examples of optimization are given. The optimization results show that there is a significant improvement on sharper focus by using this continuous phase filter with cosine function when the numerical aperture is 0.8. The numerical results about the continuous phase filter with cosine function will also help the manufacturing of actual devices.

Based on the principle of reflection of polarized light and measurement of multi-angle multi-fitting algorithm, the influences of the film thickness of the material, the noise factor in actual measurement and the special angle of incidence on the measurement accuracy of film parameters are studied. Numerical simulation of SiO2 thin film sample analysis shows that the inversion error is smaller when the film thickness is greater than 150 nm, while it is large for film thickness below 50 nm; the smaller the noise the higher the measurement accuracy; there is a special angle of incidence for SiO2 films large error even wrong result will be generated if the initial angle of incidence is set at this special value. Selecting the initial angle of incidence to deviate from the special angle by ±2° can eliminate the impact of special points.

The working principle of Geiger-mode avalanche photodiode (GAPD) is analyzed, and then the activating model of GAPD via splitting the sample time into even time bin is established. Based on this result, the photon counting detection probability and noise model are enlisted, and according to the noise model the probability of false alarm (PFA) is calculated. The models of signal returned from diffuse target and glint target, are analyzed, finally the detection-probability model of photon counting combined with the noise and probabiliy of detection under the threshold are obtained.

Based on the principle of the reflection of polarized light, the measurement of refractive index of the medium is achieved. The highly collimated diode laser is incident on the surface of samples. By gradually rotating the sample or changing the angle of incidence of the sample surface, the relation curves of the test samples′ reflected light intensity versus the incident angle is obtained. When p polarized light is used, there is an incident angle at which the changing rate of the curve approaches zero. The corresponding angle of incidence is called the Brewster angle. According to the principle of the reflection of polarized light, the sample refractive index can be figured out. We use this method to measure the refractive in dices of glass sample and a prism. The deviation of measurement result is at the order of magnitude of 1×10-3, and the measurement repeatability is pretty good.

Reflex light-tubes are widely used in optoelectronic measuring systems such as in ships, vehicles and so on. To make the optical path reflex in altitude direction and keep the incident light parallel to the emergent light in azimuth transmission, the reflex light-tubes are needed, which finally ensures precision transmission of the azimuth reference. The flat mirror method and the mercury method are used to test the optical-axis parallelism of reflex light-tubes shorter than 1 m, however when the methods are applied to reflex light-tubes longer than 3 m, the accuracy required cannot be reached. A new test method of optical-axis parallelism for three-meter reflex light-tube is introduced and it is well suited for testing the parallelization of reflex light-tubes more than 3 m.

A remote voice detection system is designed. Laser output light is focused on the surface of the forced vibrated glass nearby the sound source, and the reflected light, carrying the information of the sound source, is converted to electrical signals by the photodiode. The signal is amplified and sent directly to a speaker to obtain the remote voice detection. A computer sound card which is the essential part of the apparatus because it processes signals from the photodiode is designed. Signals analysis system is also designed based on LabVIEW software. Testing results show that the system can detect the voice signal from an analog room in a distance of 50.7 m with high sensitivity. This design is simple operation, low manufacture cost.

The 90°-arc-bend waveguide which connects the Γ-K and Γ-M waveguides is designed based on two-dimensional triangular lattice photonic crystals. The double-photon localization of Bragg reflection and total internal reflection is achieved by the introduction of defect surfaces on the arc and both sides of the Γ-M waveguide. Thus, the 90°-arc-bend waveguide based on two-dimensional triangle lattice photonic crystal with transmittance of 90% was realized in simulation.

When oceanic lidar detects the underwater target, the detection depth will be influenced by the wavy surface. The spatial distribution of the photons on the target plane has already become the focus of the research. Most of the work that has been done is about radial distribution of photons in the small-radius region, while research about the photon diffusion on the target plane in wider region is very little. Based on Monte Carlo method, through the comparison between abandon and select sampling and transform sampling, the radial distribution of photons in big-radius region has been analyzed. The results show that, for the same radius, the radial distribution of the photons′ relative energy and the wind speed follow some rules. That means the randomness due to the wind speed is not completely random, there are some rules too. Meanwhile, the comparison between abandon and select sampling and transform sampling shows that transform sampling is only as an approximation, and its result is not as accurate as abandon and select sampling.

Using 32.4 mg CuCl2 powder, the CuCl2 aqueous solution with the concentration of 1.62×10-4 is prepared. The CuCl2 aqueous solution plasma is produced by focusing the 1064 nm Q-switched NdYAG laser onto it. The plasma temperature of 1850 K is inferred using Boltzmann plot method, while the electron density of 5.8×1016 cm-3 is obtained from the Stark broadening of the profile of Hα 656.273 nm. Based on experimental results, the laser-induced CuCl2 aqueous solution plasma is verified to be in local thermodynamic equilibrium.

The end cap working face is strengthened by Nd:YAG laser, and alloy layer of TiC is obtained. The phase composition, microscopic structure and wear-resisting property are analyzed by X-ray diffraction instrument, microhardness tester, scanning electron microscope and energy dispersive spectroscope. Analysis and tests indicate that the main phases of alloy layer consist of martensite, retained austenite, Cr23C6 and TiC. The microstructure of the alloy layer is fine, without microcracks, pores or other defects. The alloy layer is metallurgically bonded to the substrate, and its microhardness is up to 358 HV, which is about 1.6 times of that of the substrate. The wearout surface is relatively smooth, without obvious furrows or spalling phenomena.

Multiple factors and their multi-level effects on the three-dimensional (3D) residual stress field by laser shot peening (LSP) are considered comprehensively, and the model of secondary fuzzy comprehensive evaluation is established based on fuzzy mathematics theory. With such a technical method, the relative merits of residual stress field in LSP by finite element analysis are evaluated, and the fatigue simulation tests of the specimen treated by LSP are done. The fatigue life results show that fuzzy comprehensive evaluation for 3D residual stress field by LSP is effective and feasible. This method will provide guidance for the optimization and control of 3D residual stress field by LSP.

In laser shock processing with circular laser spot, reverse plastic loading originating from the boundary of unaffected area will result in “residual stress hole” phenomenon. The “residual stress hole” phenomenon is proved by microhardness and residual stress test results of titanium alloy TC17, stainless steel 1Cr11Ni2W2MoV, aluminium alloy LY2 and Ni-based alloy K417 processed with single circular laser spot. Especially, the received effect laws of laser power density and impact times to “residual stress hole” phenomenon are studied. In order to reduce the influence of “residual stress hole” on the uniformity of strengthening, titanium alloy TC17 is chosen to study the optimized overlap rate and impact times. Results show that compared with single spot processing, with the same parameters, appropriate overlap rate and impact times could efficiently restrain the effect of “residual stress hole”. Particularly, with the overlap rate of 66% and impact times of three, the average value of microhardness and residual stress are increased by 60 MPa and 30 HV0.2, and the differences are reduced by 70 MPa and 94 HV0.2, respectively.

The low-coherence light interferometry is used to avoid the spurious fringes when the surface profile of optical parallel plates is tested by laser interferometer. The sodium light, a low coherence light, is used on the Twyman-Green interferometer, therefore the lights reflected from the front and rear surfaces of optical parallel plates will not interfere with the reference light simultaneously. So the spurious fringes are avoided. The captured interferogram is processed with the virtual grating phase-shifting moiré fringe method. The front suface of a parallel plane is measured using Zygo phase-shifting interferometer, whose result coincides with the one obtained by the Twyman-Green interferometer.

The characteristics of the dynamic infrared (IR) scene simulation technology based on digital micro-mirror device (DMD) include large dynamic range, high spatial resolution, high frame rate, good uniformity, small volume and so on. It can simulate infrared scene in the laboratory, reduce the research cost of the infrared system and shorten the development cycle. According to the requirements of the infrared scene simulation system based on DMD, the characteristics of the infrared projection optical systems are analyzed, and the technical indices of the projection system are determined. The selection of initial structure is presented. The infrared projection system of high image quality and high performance-price ratio is designed for the wave band of 8~12 μm based on the aberration balance theory and aspherical technology. This system for DLP5500 DMD (1024 pixel×768 pixel) is composed of three refractive lenses. The focal length is 200 mm and the relative aperture is 13. The optical system image quality is evaluated with Zemax optical design software. The result shows that modulation transfer function (MTF) of the system is close to the diffraction limited curve. The spot diagram root mean square (RMS) value of each field of view is smaller than the radius of Airy disk. The system meets the requirements of technical specification.

A design method of the single-chip capsule endoscope with harmonic diffraction surface is introduced with the system working band of 0.486~0.656 μm and the field-of-view angle of 116.2°. And the total length of the optical system is 2.4 mm. Additionally, a capsule endoscope with three spherical lenses and a single-chip capsule endoscope with aspherical surface are designed, and a comparison is made between them and the single-chip capsule endoscope with harmonic diffraction surface. It is found that the single-chip capsule endoscope with harmonic diffraction surface can achieve the image quality of the capsule endoscope with three spherical lenses. and its construction is as simple as the single-chip capsule endoscope with aspherical surface. Its modulation transfer function is greater than 0.6 at the frequency of 40 lp/mm.

A design study of athermalization of switchable dual-field-of-view optical systems for 7.7~9.7 μm is presented. With the axial motion of a lens group, a result of dual-field-of-view infrared optical system is achieved. In order to meet a wide environmental temperature range, the optical passive athermalization is used to eliminate the thermal effect in optical systems by correctly assembling different optical materials. The final optical designs along with their modulation transfer function (MTF) and root-mean-square (RMS) radius are presented, showing excellent imaging performance in dual fields-of-view at the temperature range between -60 ℃ and +70 ℃.

In order to solve the practical problems about the characteristics instability or loss to the optical system of the large solar simulator because of the overheating source, the radiator of the large solar simulator is studied. Through heat conduction analysis and the establishment of three-dimensional model, we established the radiator mathematical optimization model in working large solar simulator. Multi-objective parameters consisting of heat dissipating capacity, structure and solid mass of radiator were optimized based on the finite element analysis and the optimize regional value setting, and the final results of optimization show that heat dissipating capacity is not less than 11000 W when radiator mass is not greater than 16 kg. This scheme provides an effective design method for the optical equipment with the large size and the high working temperature.

This paper describes an introduction in both setup and rate equations of stimulated emission depletion (STED) fluorescence microscope. The methods of generating STED beam and a series of phase plates used in STED fluorescence microscope are introduced. The development of the setup on STED fluorescence microscope, including broadband STED, continuous-wave (CW) STED, multi-color STED, fast STED and single-wavelength two-photon emission (SW2PE) STED, is described. Future prospects for the development of the STED microscope experimental setup is put forward; new laser sources, new phase plates, three-dimensional (3D) super-resolution, and a variety of imaging modalities combined imaging are the main development directions in the future.

Since the efficiency droop at the high current density of the InGaN-based light-emitting diodes (LEDs) influences the application of power-LEDs, the origin and the overcoming method of the efficiency droop have become a hotspot. Several possible mechanisms are discussed, such as Read-Shockley-Hall (RSH) recombination, Auger recombination, carrier localization, polarization field, efficiency of injected carries and heat effect. Some methods for overcoming efficiency droop are also discussed.

Cross metal array structure is experimentally studied by terahertz time-domain spectroscopy (THz-TDS). The results show that this kind of structure have the characteristic of non-polarized narrow band filtering. Most terahertz wave can pass through the cross metal array structure. However, the terahertz wave with certain frequencies is restrained by the structure. Moreover, the change of polarization angle does not affect the position of transmission dip. It is proved that the structure is a good non-polarized transmission and filtering device in the terahertz band. These results provide a good reference for the research and fabrication of terahertz sub-wavelength optical components.

Traditional genetic algorithms (GA) are of good ability of global search because of its parallelism, while tabu search algorithm is of fast convergence and great local search capacity. Combining the advantages of genetic algorithms and tabu search algorithm, a new algorithmgenetic/tabu hybrid optimization algorithm is proposed to design multilayer coatings. The theory of tabu search is imported into the crossover and mutation processes of GA, which makes the algorithm have the ability of memorizing. Better designs are obtained using genetic/tabu hybrid optimization algorithm to design antireflection coatings and beam splitter than the traditional GA. The results indicate the effectiveness and reliability of the algorithm.