Tunnel visibility has an important relationship with traffic safety. Real-time monitoring of tunnel visibility can provide a strong basis for ventilation and ventilation of tunnels. Based on the principle of visibility detection by transmission method, a set of visibility detection system is built for automatic detection of tunnel visibility. The detection system is mainly composed of a laser diode, a beam splitter, a silicon detector and a signal processing unit. Two silicon detectors detect the intensity of light before and after attenuation through optical path respectively and output corresponding photocurrent. The signal processing circuit amplifies and filters the output of the detector and converts the output to AD, and then calculates the extinction coefficient. Fixed transmittance filter is used to simulate tunnel environment, and the performance index of the detection system is tested in laboratory environment. The experimental results show that the measurement range of extinction coefficient is 3.37 km-1～118.82 km-1, the maximum relative measurement error is 8.4%, and the stability is better than 0.12 km-1.

Satellite cloud imagery can show the features and the evolution processes of all kinds of cloud systems from different aspects. Thus, adopting the content-based cloud image retrieval makes a big difference in supervising present weather conditions and studying the climate change. In order to optimize the combined features of the cloud picture and strengthen the generalization ability of its combined features, this paper presents an optimal method of combining the features of the sparse representation with the subspace projection. At first, we should extract its color, texture and shape, convert all the combined features, and divide them into different blocks. Then, we can make the sparse representation for each block’s features, grouping them according to different atom variance and gaining both noticeable and unnoticeable features. Finally, we can count the power of the grouped features to get the subspace projection matrix, projecting the original combined features on it and achieving the optimal cloud picture features. The experiment turns out that the method of optimizing the cloud picture features in this paper is better than common descending dimension method and cloud retrieval technology in precision ratio and recall ratio. It indeed has a stronger optimization in the combined features as well as a lower time complexity in the process of the real-time retrieval, which indicates a brand new retrieval method.

In the lithography process of thin film transistor, the lithography plane position of photoresist is the key factor that determine the quality of lithography pattern. In order to improve the quality of lithography pattern under the minimum resolution of lithography machine, the reflection characteristic of the light in the photoresist is studied in this paper, based on reducing the intensity of the reflected light in the photoresist on the non-lithography region and increasing the intensity of the photoresist at the bottom on the lithography region, the computational formula for the lithography plane position adjustment of the photoresist is deduced under the oblique incidence. The adjustment amount is calculated by the formula and the lithography plane is adjusted by the adjustment. The results show that for the projection lithography machine with the minimum resolution of 3.0 μm, and for the product with the line space of 2.2 μm, after adjusting the lithography plane of photoresist with this adjustment，the slope angle of the lithography pattern is increased by 13.3%，and the uniformity of the DICD (development inspection critical dimension) is improved by 14.7%，the photoresist remain of the lithography pattern is resolved.

In order to improve the performance of Ga2O3-based photodetectors (PDs), Sn-doped gallium oxide thin films were prepared on sapphire substrates by molecular beam epitaxy system. The influence of Sn doping on both Ga2O3 crystal structure and photoelectric properties of metal-semiconductor-metal (MSM) PDs were investigated. X-ray diffraction shows that gallium oxide films change from single crystal to polycrystalline phase when increasing the growth temperature of SnO2. When 254 nm and 42 μW/cm2 light was used, the responsivity of Sn-doped Ga2O3 photodetectors reached 444.51 A/W. Compared with the undoped β-Ga2O3 PDs, the photocurrent and responsivity of Sn-doped PDs were almost increased by two orders of magnitude, suggesting the improvement on PD performance. Spectral response shows that the cut-off wavelength of Sn-doped PDs changes from 252 nm to 274 nm by increasing Sn dose, which reveals an efficient way toward the development of the UV PDs focus on longer wavelengths. However, Sn doping also introduces impurity levels, resulting in poor time response of the MSM PDs.

To solve the problem of low stability of fusion validity measurement in existing fusion of infrared intensity and polarization images, the stability of various fusion algorithms for the distribution of fusion validity of different features was analyzed and compared by using three common fusion validity function measurement methods based on measurement distance. By calculating the frequency of the optimal fusion algorithm in difference feature amplitude interval of ten groups of images, the optimal fusion algorithms for each difference feature were obtained, and cosine similarity was obtained as a measure of fusion efficiency with high stability and more consistent with subjective observation results of the humans. The experimental results show that the cosine similarity has high stability and good matching with human vision analysis in the fusion effectiveness measurement of various fusion algorithms.

In order to study the influence of underwater thermal disturbance environment on imaging distortion, such as optical imaging distortion or imaging blur, the level of distortion of target image in radial and axial directions was evaluated by using the gray scale distribution, structural similarity image measurement (SSIM), and normalized maximum gray-scale gradient definition evaluation function of underwater images. Furthermore, the laws of underwater thermal disturbance on optical imaging changes were obtained. Experimental results show that with the increase of the axial distance between the imaging system and the target, the level of image distortion and blurring becomes larger and larger. When the axial distance is equal to 500 mm, the SSIM is better than 0.7 and the normalized definition is better than 0.8. When the axial distance reaches 1500 mm, the SSIM is lower than 0.2 and the normalized definition is less than 0.6. In addition, when the axial distance equals 500 mm, the drift of the edges will be greater as the imaging area comes closer the heating source in the radial direction, that is, the imaging distortion is more serious. Finally, under the same axial and radial conditions, the conclusion that the SSIM and normalized definition values of the target images are different at different times can provide a reference for further underwater image restoration.

Aiming at the measurement problem of high cost and low precision in dynamic angle, an electro-optical measurement method based on non-cooperative target vision tracking is presented. By using electro-optical servo platform mounted on the measured object to carry the camera and the laser rangefinder for the real time tracking and distance measurement of the non-cooperative target, the dynamic angle value is calculated according to the conversion relationship between the high precision angle of measurement of the servo system and the distance of the non-cooperative target. A dynamic angle measuring device is developed, and its precision calibration and error analysis are carried out. Using the high precision manual displacement table to simulate the measured dynamic angle to experiment, the feasibility of the measuring method is verified. The experimental results show that the measured angle error is 0.09° within the range of 11.082 m.

We present a way to achieve the compact augmented reality (AR) smart glasses with a large field of view(FOV). A planar waveguide and embedded narrow band minus filters are used for image transmission and coupling. The optical system based on the method is simple in structure and has the advantages of small size and lightweight. A geometric model for the propagation of light in the waveguide is constructed. Based on this model, the constraints of the structure and the dependence of designed parameters with viewing angles are analyzed. According to the calculations, a 3 mm thick waveguide is fabricated to investigate the feasibility of the theory. Experimental results demonstrate that the prototype can deliver a projected image and realize the fusion of the virtual image and the real scene as expected, the measured viewing FOV was about 50°.

Edge detection is a key step for the online vision measurement of lithium battery coating (LBC). However, as the vibration and rectification in LBC production, the virtualization and curling of edges could occur. In order to improve the accuracy and efficiency of on-line measurement of LBC, this paper proposed a staged edge location method according to the production characteristics of LBC, and achieved the swift and accurate detection of edges. Firstly, a cross neighborhood operator is used to detect the edge preliminarily to improve the ability of week edge detection. Then, local extreme values difference (LEVD) algorithm with selective peak sort algorithm is proposed to guarantee for the ability of edge-preserving and anti-noise of edge projection and to improve the efficiency of edge detection. Finally, piecewise cubic spline interpolation combined with segmented linear fitting method is provided to realize the sub-pixel location of the edge. The experimental results show the effectiveness of the method.

The point measurement laser absorption spectroscopy (PMLAS) based on saturated absorption theorycould surpass the defect of ‘line-of-sight’ measurement in traditional tunable diode laser absorption spectroscopy(TDLAS) and achieve the ‘point’ measurement with millimeter spatial resolution. It is realized by crossing with twofrequency synchronized laser beams: one named probe beam as in traditional TDLAS and the other named saturatedbeam with higher power. In this paper, the theory of PMLAS was firstly analyzed by the theoretical deduction ofsaturated absorption coefficients with arbitrary cross angles and the numerical calculations of point absorbanceunder different saturation parameters. Next, a weak signal detection method based on high-frequency sinusoidalmodulation of the saturated beam intensity was proposed, in which the first-order harmonic signal was theoreticallydeduced and verified by numerical demonstration. Furthermore, it is found that the FWHMs (full width at half maximum)of different order harmonics are all the same and equal to the width of the absorption signal without modulation,which implied that the superposition of multi-harmonics could enhance the signal-to-noise ratio (SNR) in measuringthe spectrum line-width.