In order to study the atmospheric transmission characteristic of 1.54 μm and 1.06 μm lasers and the impact on laser ranging, Modtran is used to simulate the atmospheric transmittance of 1.54 μm and 1.06 μm lasers in different conditions which include atmospheric molecules, aerosol and fog. The laser ranging principle is used to get the relationship between the maximum range of pulse laser rangefinder and atmospheric transmittance. The results point out that, the impact of atmospheric molecules is negligible. Decrement of aerosols to 1.06 μm laser is heavier than that to 1.54 μm laser, and humidity is the key factor. Fog has very heavy decrement to both of the lasers, and they have almost the same atmospheric transmittance in fog. The reduction of visibility has heavy impact to the maximum range of pulse laser rangefinder. Since 1.54 μm laser has better atmospheric transmittance than 1.06 μm laser, pulse laser rangefinder which uses 1.54 μm laser has advantage in the aspect of maximum range.

The signal-to-noise ratio (SNR) of communication system is variable with channel status and circuits noise. We analyze the turbulence index and irradiance variance, and then establish the relationship between Rytov index of the atmospheric turbulence and SNR of intensity modulation free space optical communication (FSO) system. Firstly, the multiplicative noise induced by irradiance is analyzed. The relationship between irradiance variance and SNR of the FSO system is introduced. Then two common noise models are introduced to simulate the multiplicative noise. The relationship among Rytov index, irradiance variance and SNR of FSO system is derived. At last, the experimental measurement data under different weather conditions are used to prove the simulation results. The results show that there is a linear relationship between Rytov index and variance of intensity in weak turbulent weather. SNR of FSO system relatively decreases as the Rytov index increases. While in medium to strong turbulent weather, variance of intensity converges towards saturation, and SNR tends to a stable value.

To evaluate the evolution of response of solar blind ultraviolet (SBUV) intensified CCD (ICCD) versus working time, a novel fatigue property testing scheme is proposed and actual experiments are carried out for two typical work patterns. At first, two typical working modes for SBUV-ICCD are introduced based on the fundamental construction and principle. Secondly, the device fatigue property is defined and a novel fatigue testing scheme is designed. Finally, fatigue testing for two SBUV-ICCDs is done and their uncertainties are analyzed. The testing results show that the fatigue properties of a homemade SBUV-ICCD in photoelectric simulation mode and photo counting mode are 13% and 3%, respectively, while the corresponding parameters of an abroad SBUV-ICCD are better than 1%, and the scheme′s uncertainty is 1%.

For a round lattice micro-structure optical fiber, the birefringence properties are simulated by the finite difference beam propagation method. After analyzing the influence of different cross-section structure parameters on birefringence, we obtain an appropriate set of structure parameters. With these parameters, the polarization beat length remains stable in a wide wavelength range near the 1310 nm communication window, and the working bandwidth can reach 200 nm, so it has a better achromatic characteristic. The fiber is suitable for making wideband achromatic plate.

According to the resources, missions and restraints, a scheduling algorithm based on view period windows refreshing is put forward and the model is established. Considering the multi-window multi-antenna structure and mission priority (PRI), the mission is scheduled reasonably and the time window is refreshed by the scheduling operation: the confirmed operator of current mission scheduling time and the refreshing of the following mission view period window. The PRI is considered as parameter in cost calculation and the scheduling project is optimized by genetic algorithm. The simulation scene includes 4 user satellites, 3 antennas and 32 missions. The simulation result reveals that the algorithm can obtain satisfactory results in both time and optimization, which is suitable in multi-mission and multi-antenna recourse scheduling.

In order to improve the quality of images captured by spaceborne optical remote sensors, a deblurring method based on constrained total-variation regularization is proposed. First of all, the deblurring problem is transformed into a non-blind one via estimation of the point spread function (PSF) using multichannel blind deconvolution. The deblurred image is obtained by applying fast gradient projection algorithm to this non-smooth optimization problem. On the inevitable existence of PSF estimation error and noise, the proposed method does not introduce significant ringing and noise amplification. Experimental results based on panchromatic remote sensing images show that it can preserve mean value and meantime increase the energy of Laplacian from 11.1455 to 57.5541. The structural similarity index between original and deblurred images is up to 0.9824. Both visual effect and evaluation indicators demonstrate that the proposed method can effectively improve the quality of remote sensing images.

For the imaging principle of multi-modal medical image, in order to make up for the shortage of the various modes of medical images, a novel medical image fusion algorithm is proposed based on the nonsubsampled contourlet transform (NSCT). Firstly, two registered source images are decomposed by the nonsubsampled contourlet transform to obtain the low frequency subband coefficients and high frequency subband coefficients. Secondly, for the low frequency subband coefficients, the fusion principle is based on the weight of local area energy. As for the high frequency subband coefficients, we choose the weight of the area standard deviation ratio as a rule. Finally, the fusion image is obtained by the nonsubsampled contourlet inverse transform. The experimental results show that the proposed method is feasible and effective, and it has better fusion performance and higher definition than the wavelet, contourlet, and wavelet+CS (CS: compressive sensing) algorithms.

In order to correct the deficiency of manual detection in the lens production process, a new method about lens-defects type recognition based on lens characteristics is put forward to make the automatic detection possible with the combination of image acquisition. After preprocessing the acquired image, the system will get the defective parameters such as area, perimeter, diameter, and so on. The types of defects are determined according to the shape characteristic, the minimum circumscribed circle and the thresholds of the different defects. The lens templates of different regions are obtained by the size of each region, the value of pixel number per millimeter and the position of the centroid. The results indicate that this method can be used to detect the main lens-defects such as points, feathers, scratches and bubbles with an accuracy of 0.03 mm, with which the detection efficiency will be greatly improved.

An image acquisition system is established to realize the automatic detection of resin lenses. The parameters of the system and algorithms for image pre-processing, feature extraction, defect recognition, etc. are investigated. The image acquisition system is built according to the size of lens and detection precision of defect. Image mosaic is realized by camera calibration. The defect images are acquired through image pre-processing. The algorithms of defect feature extraction and classification are finally discussed. The experimental results indicate that the detection precision of the system is 0.02 mm and the recognition rate reaches 96.5%, which can meet the system requirements for lens detection.

We present a design of tunable grating filter based on high-precision temperature control. We use aluminum groove to encapsulate the grating so that it is insusceptible to strain. Then we design a high-precision temperature control module composed of 3 pieces of temperature control chips MAX1978 working in parallel to monitor and control the temperature of aluminum groove, thus achieving the long-term stability of center wavelength of the tunable grating filter. The temperature accuracy can reach 0.1 ℃, with the dynamic range of 10 ℃~40 ℃ continuously adjustable. The tunable grating filter based on this temperature control module can reach 0.0016 nm wavelength stability at center wavelength. The experimental results confirm the configuration′s feasibility.

Based on the method of squashing presetting on the high temperature alloy to prepare NiCoCrAlY coating by laser cladding, the influence of squashing treated by cold isostatic pressing on the bonding interface is discussed. The research shows that macroscopic morphology of layers with pretreatment is complete and continuous and the phenomena of cracks in the coating interface are eliminated or reduced. With further study of mechanism, it is found that the thickness of the squashing decreased while the density and laser specific energy required for laser cladding increase, which are beneficial to the quality of interfacial morphologies of laser cladding.

Attempts are made to research the laser etching of quartz ceramic. Ultraviolet (UV) laser and fiber laser are used in the etching of quartz ceramic. Step tester and scanning electron microscope (SEM) are used to test the samples processed by lasers. The information of depth, accuracy and microstructure is obtained through the test. The result shows that quartz ceramic can be processed by UV laser and fiber laser. Compared with traditional means, using laser etching, quasi-three-dimensional structures can be achieved and the etching depth and area can be controlled with higher accuracy. The etching quality and quantity have a close relationship with the laser pulse, scanning speed and other parameters. The difference between photochemical and photothermal effect is the main factor leading to the different results of UV laser and fiber laser.

A Q-switched Nd:YAG laser is used to fabricate micro channels in a fused silica substrate by laser-induced plasma processing. The interior wall of the micro channels drilled by laser-induced plasma is smooth, and the depth of the channel is up to 4 mm. High-power laser beam focused on the fused silica can lead to optical breakdown, resulting from the formation of plasma. The ablation of the high temperature plasma can lead to a micro channel. We study the ionization mechanism of optical breakdown in solids by nanosecond laser pulses. The changes of optical parameters, including dielectric function, reflectivity and refraction index, are studied. We also discuss the critical free electron density of optical breakdown and calculate the range of optical breakdown.

After He ion implantation, p-GaAs will obtain higher resistivity than before. To improve the catastrophic optical damage (COD) level of 808 nm GaAs/AlGaAs laser diode bar, about 25 μm-long current non-injection areas are introduced near both facets by He ion implantation. The COD level of a conventional 1 cm laser diode bar with 19 emitters is 30W, while the He ion implantation 1 cm laser diode bar exhibits no COD failure at 42.7 W.

Commercially available blue-violet edge-emitting semiconductor laser diode with a wavelength of 405.5 nm is characterized and then operated in an external cavity with a Littrow configuration in our laboratory. A resonant cavity is formed between the blazed grating and the rear facet of the laser diode, which improves the performance of the laser diode greatly. The results show that the threshold current of the semiconductor laser diode decreases by 27%, indicating high coupling efficiency between the external cavity and inner cavity. Besides, by changing the angle of the blazed grating, the total wavelength tuning range can reach up to 7 nm.

We investigate microstructures on 316L stainless steel surface induced through using femtosecond laser with central wavelength of 800 nm and pulse duration of 130 fs at a repetition rate of 1 kHz in high vacuum. The single-pulse threshold of 316L stainless steel is obtained by experiment. The multi-pulse laser energy accumulation is experimentally studied with the laser fluences higher and lower than the single-pulse threshold, respectively. Experimental results show that with the laser fluence increasing, laser-induced periodic surface structures (LIPSSs) on the submicron scale, ripples and cone-shaped spikes on the micron scale are fabricated with single-pulse energy of 100 μJ which is higher than the threshold. And LIPSS on the submicron scale and ripples on the micron scale can also be obtained by multiple pulses with single-pulse energy of 20 μJ which is lower than the threshold.

The beam propagation characteristics are investigated in nonlocal nonlinear optical lattice analytically. The reduced Lagrange density of nonlinear Schrdinger equation is obtained by expanding the real symmetric response function in Taylor′s series in strongly nonlinear Kerr media. The problem of beam propagation can be analyzed by a variational approach, and the equations of the beam width, amplitude, phase and other parameters of the trial solution are obtained for the evolution during propagation. The beam can be looked as a particle, and its critical power is found through analyzing the potential function. The soliton propagation can be controlled by changing modulation period, modulation depth and other parameters of optical lattice. This effect has potential applications in the fields such as controlled optical switches.

Wave-coupling equations including acousto-optical (AO) polarization rotation and frequency doubling in periodically poled lithium niobate (PPLN) are proposed. The acoustic wave could either be induced from an external transducer or self-generated in PPLN driven with a cross-field radio frequency field. The proper reciprocal of PPLN is used to compensate the second harmonic generation (SHG) wave-vector mismatching, while phonon with suitable frequency may affect the pump polarization by scattering photons. Numerical simulation shows that there is a competition between the AO polarization rotation and SHG in PPLN under the phase-matching condition. The influences of the acoustic wave intensity on the polarization or intensity of three waves are studied.

We present a new variable multilevel run-length-limited modulation coding scheme. By using this coding scheme, better coding efficiency is obtained while the read out channel servo control and the channel signal-to-noise ratio (SNR) are met. Different phase restrictions can be set according to the SNR margin when the different run length is phased: short-run is phased less and long run is phased more. It can use the run-length redundancy to the extreme extent while reducing the inter-code interference of multi level run. Through theoretical analysis and experimental testing, the characteristics of this coding scheme are analyzed, and the performance of this scheme applied to DVD disc is also given through the test. The experimental result shows that the readout signal of the coding scheme has good symmetry with the raw byte error rate less than 1×10-5, and the coding scheme meets the requirements of the readout channel and servo control of DVD system.

The use of medium-wave and long-wave infrared dual-band combination can effectively improve the performance of airborne photoelectric detection device. The design method using four mirrors and optical passive athermal technology is introduced. A dual-band and dual fields-of-view (FOVs) catadioptric optical system is designed. The system consists of two parts, i.e., the four-mirror telescope system and secondary imaging aggregation system, and uses optical passive thermal design. It meets the design requirements of lightweight, miniaturization, and athermalization. The optical system works in the 4.5~5.1 μm and 7.7~9.7 μm wavelength bands. It can achieve the zoom of 100 mm and 300 mm, with the zoom ratio of 3, F number of 2, and a compact structure and can meet 100% cold shield efficiency. The final optical design along with their modulation transfer function (MTF) is presented, showing excellent imaging performance in dual FOVs and dual-band at the temperature range between -60 ℃ and 70 ℃.

In order to analyze the effect of optical material inhomogeneity on the image quality of optical systems with extremely small aberration, and guide the optimization of the optical systems, we propose a three-dimensional simulation and ray-tracing method. This method works in Zemax, using a self-defined program to build the three-dimension distribution of the material inhomogeneity. By setting the setp of the ray-tracing process and controlling the ray-tracing process, the simulation precision is enhanced. As an example, We study an optical system with numerical aperture (NA) of 0.7, wavelength λ=632.8 nm, wavefront aberration root-mean-square (RMS) value of 1.5 nm. The simulation result shows that the simulation precision of this three-dimensional simulation and ray-tracing method is obviously better than other two-dimensional methods.

The lighting collimating lens is designed for the use of headlight of automobile, in which LED is used as lighting source. Firstly, the simplified illumination structure model is built, which is designed based on the theory of non-imaging optics and the parameters of traditional lenses. The structure is optimized by optical simulation software Zemax. Secondly, the three-dimensional (3D) model of lens is set up by SolidWorks software and simulated by TracePro. The results show that the optimized lens′ light-use efficiency is improved by about 6%. Thirdly, the optimized lens is made and prepared for test. Finally, the experimental system is set up, by which the optical characteristics of the traditional and optimized lenses are investigated. The results show that the maximum light intensity is improved by about 128% at 5 m away and the irradiated area at the same illumination (50 lx) is enlarged by about 25%.

Due to the difficulties of judgments in magnesium and its alloys′ ignition points and problems of measured temperature field distribution influenced by thermocouples, short lifespan and inconvenient miniaturization, a new kind of colorimetric temperature test device is designed. The basic structure and test principle of this device are introduced. According to the inflection point of changes in two channels of received optical radiation, the burning time is confirmed and the corresponding temperature is just the ignition point. A fiber optic spectrometer is used to test the spectra before and after combustion, which provide a reference for choosing system′s wavelength and bandwidth, and temperature correction is performed with calculating the ratio of emissivity. A temperature of blackbody furnace is used to do static calibration for the colorimetric test device to decide the systematic wavelength and bandwidth. Finally, a CO2 laser is employed as the heat source to ignite pure magnesium and magnesium alloy AZ91D. The colorimetric temperature test device and infrared thermometer are used to do ignition test. The results test show that the relative error of pure magnesium and magnesium alloy AZ91D are 1.43% and 1.08%, respectively.

Pure phase spatial light modulator can be used in many kinds of precision optics, and the prerequisite of correctly using this kind of spatial light modulator is the proper Gamma correction. We complete Gamma correction for a new type of Holoeye Pluto spatial light modulator by simply using the double-hole interference method and Webcam. The results show that the first order diffractive efficiencies of 8-level and 16-level blazed grating reach 70% and 80%, respectively; by displaying vortex hologram, LG01 doughnut beam is generated very well, which is sensitive to the aberration and the deviation of the phase modulated by the spatial light modulator. The stability of the modulated phase is also measured, and the variation upper limit or the averaged standard deviation is 2.43°.

With increasing output power of fiber lasers, the fabrication of high power laser fiber requires larger sized core rod and more precise control of the refractive index profile of rare earth doped fiber preforms. However, most of the existing preparation techniques of rare earth doped silica fiber preforms are based on the processes which were used to produce communication fibers and their limitations have gradually emerged. Therefore, it is urgent to develop new techniques to fabricate high power laser fiber performs. In this paper, some newly developed preparation processes of rare earth doped silica fiber preform are elaborated, and then their advantages and shortcomings are discussed in detail.

The research progress of femtosecond laser microstructuring silicon surfaces is summarized. The formation mechanism of the deep subwavelength structure of silicon surfaces induced by ultrashort pulse is introduced, the influence factors of the preparation of micro-nano structures with femtosecond laser irradiating silicon surfaces and the luminescence properties of the micro-nano structures are discussed. The biological bionic characteristics of the micro-nano structures of silicon surfaces induced by femtosecond laser are introduced. The widespread application prospects of femtosecond laser in the preparation of the microstructures are put forward.

The principle and technique characteristics of phase-modulation to intensity-modulation conversion (PM-IM), which is widely used in microwave photonic system, are analyzed. Categories of PM-IM are summarized. The applications of microwave photonic filter, ultra-wideband (UWB) system, all-optical microwave generation, microwave frequency conversion and instantaneous microwave frequency measurement are introduced in detail, and the advantages of PM-IM are discussed. At last, it is pointed out that the research directions of PM-IM are improving rate and precision, reducing insert loss and improving system reliability.

Photoelectric shaft encoder is an advanced digital angle transducer. Velocity measurement can meet the demands of modern precision servo control system using photoelectric encoder with the advantages of high precision, high resolution and high reliability, therefore, the research has been a popular topic. we introduce the principle and application of photoelectric shaft encoder. Then the applicability, advantages and drawbacks are presented by introducing and comparing various velocity measurement methods. At last, the development trend of velocity measurement methods with photoelectric shaft encoder is prospected.

The sample of laser cooled atoms significantly improves precision measurements of atom spectrum due to its advantages such as longer interrogation time, elimination of Doppler and collision-induced shifts, weak coupling to the interrogating fields and so on. The benefits of cold atoms have attracted large interest in navigation field. The development history of navigation sensors based on cold atom is reviewed and the recent research status of cold atom navigation sensors is introduced. The navigation sensors are classified into three types according to their different structures, and the physical effects, operation principles, performance parameters and application fields are described respectively. Finally, the development tendency is prospected. It is pointed out that the high-g dynamic environment and the integration and package of the system will be the main challenges for the practical application of cold atom navigation sensors.

Switchable retroreflecting films are the new type of retroreflector by modulating (flashing) the retroreflected light for enhanced visibility and night vision applications. There are five types of viable constructions and operating mechanisms for switchable retroreflector, including integrated electrowetting scattering, integrated and external electrowetting light valve, external liquid crystal light valve and external liquid crystal scattering. This paper gives broad comparison and discussion about the characteristics of five technologies for further development of switchable retroreflecting films.