In recent years， functional devices based on optical fibers have been widely used. Compared with traditional sensors， optical fiber sensors have many advantages， such as low cost， small size， light weight， high sensitivity， adaptive to severe environment， electromagnetic interference immunity， and so on. This paper reviews the development history and basic concepts of optical fiber. According to the two categories of traditional optical fiber and micro-structured optical fiber (photonic crystal fiber)， the sensing systems applied to temperature， humidity， stress， magnetic field and other parameters are introduced， especially the fabrication of liquid-crystal-injected photonic crystal fiber and sensing application of this type of fiber based on their birefringence characteristics. Finally， this paper proposes the concept of “Lab on fiber” and looks into the future development trends of optical fiber sensing.

The accurate count of blood leukocytes is very important for the diagnosis of blood diseases， and the accuracy of blood leukocyte segmentation is an important pretreatment step to correctly determine the type of blood leukocytes. The B component and G component of blood leukocytes have obvious difference under different staining conditions and different lighting conditions. Accurate blood leukocyte segmentation is performed based on Otsu threshold processing and area threshold processing. Through the establishment of mathematical model， based on the morphological characteristics of intact leukocytes and lobulatednucleus leukocytes are classified and judged. The edge detection of lobulated leukocytes with mitosis is carried out， and the number of lobulated leukocytes is determined according to the maximum and minimum distance， so as to realize the accurate counting of blood leukocytes. Experimental results verify the feasibility and practicability of the proposed segmentation method.

Vehicle head-up system is the inevitable trend of the development of vehicle instrument display in the future. However，in the process of free-form mirror measurement in head-up display system， the features of different regions are similar， which leads to be difficult to extract feature points， and to fall into local minimum value during optimization. A high-precision method for matching the three-dimensional point cloud with the head-up display mirror surface model is proposed in this paper. Firstly， the measurement data and model are converted into point cloud files， and after three-dimensional rotation， the normal vector of each point cloud is parallel to the Z axis， and then point cloud is projected to the XOY plane， which will not cause overlap and occlusion. Secondly， edge points are extracted in the two-dimensional plane， and the corner points of the edge are extracted. The rotation angle is calculated by determining the corresponding corner points， and then the corresponding rotation of point clouds is completed in the three-dimensional space. Thirdly， the rough matching is completed， and the fine matching is completed by minimizing the objective function. The algorithm in this paper uses the edge features of free-form surface mirrors for matching， avoids extracting local feature points， and does not fall into local minimums during the optimization process， and can accurately calculate the error of the tested surface.

In order to explore the influence of different array element parameters on the acoustic field of phased array ultrasonic array transducer， based on the basic principle of phased array ultrasonic detection and acoustic field radiation theory， the numerical simulation analysis is carried out by using MATLAB software， and the radiation acoustic field model is established， and the directivity and acoustic field of array transducer under different parameters are analyzed. The comparative analysis method is used to analyze the influence of various parameters of the array element on the beam quality， focusing range and imaging effect. The conclusion is that the imaging resolution will be too low if the array center frequency is too small， and the acoustic field penetration is weak and the detection depth is shallow. The increase of the number of array elements can significantly improve the imaging effect， but it also greatly increase the cost. The width of the array element will increase when the center distance of the array element increases from 0.1 to 0.3， the imaging effect is significantly improved， and then to 0.6， the improvement is not obvious. The increase of the array center distance will improve the focusing accuracy and imaging effect， but when it is more than 0.8， the imaging effect drops sharply. When the deflection angle is less than 30°， the imaging effect is stable and clear. When the deflection angle is too large， the imaging effect will be significantly worse. If the focusing depth is too small， the acoustic beam focusing property is poor， and the imaging effect is not good， and the focusing depth is greater than the detection surface， the imaging effect is good. This conclusion has certain practical significance for guiding the actual ultrasonic phased detection.

In order to establish the equivalent model of the electro-optical servo system， it is necessary to analyze the electromagnetic interference of the system. Based on the non ideal characteristics of electronic circuit devices and the parasitic characteristics of coupling paths， the behavior level simulation model of servo drive circuit is established. Combined with ANSYS software platform， multi domain collaborative simulation is carried out to predict conducted interference emission. Through the model， the influence of high frequency drive and RC absorption circuit on interference characteristics are quantitatively demonstrated. In the test platform， it is verified that the trend of the frequency spectrum curve between 150 kHz and 10 MHz is basically consistent with the measured spectrum curve， which indicates that the model can be used as a feasible scheme to predict and evaluate the electromagnetic compatibility of servo drivers.

With the development of optical communication technology， the information interaction and transmission are becoming more and more numerous. Polar code is theoretically the only channel coding technology that can reach the Shannon limit， which can effectively reduce the transmission error rate. Therefore， it is of great significance to study the Pola code and its application in OFDM optical communication systems. Combining the advantages of Polar codes， the OFDM optical communication channel coding technology based on Polar codes is studied in this paper， and the algorithm simulation is carried out. The simulation results show that when the same decoding algorithm is used， as the length of the Polar code increases， the error rate gap between different systems becomes smaller and smaller， which can effectively shorten the decoding time and reduce the complexity of decoding.

A new bi-color 2+1 three-dimensional real-time measurement method is proposed in this paper. The traditional three-dimensional real-time measurement method based on 2+1 algorithm needs to project two frames of phase-shifting grating and one frame of background image. In this method， only two frames of bi-color gratings are needed to be projected. Before measuring， two frames of bi-color gratings are encoded in advance. The red channels of these two bi-color gratings are sinusoidal fringes with a shifting phase of π， and the blue channels are the same background light equivalent to the DC component of these sinusoidal fringes， so the sensitivity ratio of color CMOS camera red to blue channel can be calibrated. During the measurement， two frames of bi-color gratings are encoded with a phase shift difference of π/2 according to the above method and synthesize them into a repetitive video. The repetitive video is projected on the surface of the object to be measured by a projector， and the color deformation fringe image can be collected in real time by using a color CMOS camera. The sequence of color deformed fringe patterns at different moments is extracted by computer processing， so as to realize real-time online 3D measurement of moving objects by using 2+1 algorithm . This method can effectively reduce the color crosstalk by using red and blue channels， and only two frames of bi-color gratings are projected to improve the real-time performance of the measurement. Experimental results and analysis verify the feasibility and effectiveness of the method applied to real-time object motion.

Before the binocular structured light measurement system working， it is necessary to use a three-dimensional (3D) target or a planar target for system calibration. In order to obtain good result， customized high-precision and expensive targets are usually selected. However， once the chosen target is completely produced， the established characteristic parameters make the binocular system that can be calibrated is relatively fixed， so the flexibility of such target is limited. When the measuring field of a 3D measurement system is small， in order to reduce the cost of calibration， and hope the calibration target design can be flexible and adapted to the calibration of multiple measurement systems， a smartphone screen display target is used in the calibration of a small-field binocular 3D measurement system for final 3D shape reconstruction based on fringe projection. Meanwhile， a customized planar target is used to calibrate the same measurement system. The comparison and analysis of the results of two targets verifies the feasibility of the smart phone screen display target as a calibration target for a small-field binocular 3D measurement system.

In this paper， a measurement method of stress birefringence based on photoelastic modulator is proposed and studied theoretically. Based on the measurement principle， the mathematical model is established. According to the mathematical model， the received signal is analyzed， and the calculation method of phase delay is proposed. In this method， DC component and first harmonic component are used to settle the phase delay， which can eliminate the influence of instrument constant on measurement results. Moreover， it is the most sensitive to the measurement of the phase delay near 90° and reliable for the sample with the delay between 45° and 135°. The numerical simulation analysis is carried out by using MATLAB. The wave plate with theoretical delay of 74.17° is measured， and the average measurement result is 74.28°. The experiment proves that the measurement scheme is accurate and reliable.

Static stiffness is an important safety index of hoisting machinery， and its main measurement parameter is the deflection value of the crane girder in the case of no-load and specified load. Before and after loading， the gray features of the bottom boundary of the beam remain stable， and the displacement of the beam boundary in the image plane can be accurately calculated by using the digital speckle correlation algorithm. When the parameters of the optical imaging system are known， the actual displacement of the beam can be accurately calculated from the displacement in the image plane. Combined with the characteristics of oblique axis imaging， the static stiffness measurement system is built， and the measurement error of the oblique axis optical system is analyzed， and the selection of sub region location and sub region size is optimized. The system is used to measure the movement of the simulated girder， and the error is within 0.2 mm. The static stiffness of the crane girder is measured at a distance of 30 m， and the measurement results are consistent with those of the control method， which indicates that the method could meet the requirements of the static stiffness measurement of the crane girder.

The defocused projection of binary fringe overcomes the nonlinear effect of fringe projection on 3D shape measurement， and effectively suppresses the error caused by Gamma effect of the used projector. Multi-frequency binary defocused fringe projection combined with temporal phase unwrapping is a common 3D shape measurement method for complex objects. In its application， it is necessary to ensure that multiple frequency binary fringes can get approximately the same sinusoidal quality， and the defocusing amounts of different frequency fringes are different， which is not conducive to its wide use. In this paper， the relationship between the defocused amount and the sinusoidal quality of the fringe with different binarization methods is analyzed， and a method of 3D shape measurement is proposed by using different binarization methods with the same fixed defocusing amount while projecting the different frequency fringes. The comparison， simulation and experimental results of the combined binary fringe method in this paper and the single frequency binary fringe method show that the combined binary fringe method proposed in this paper has higher accuracy and the defocusing amount of the fringe at different frequencies is fixed in practice， which is convenient and easy to operate.

Bubbles， impurities， scratches and other defects in the inner optical elements of the lens will seriously affect the imaging performance of the optical system of the security lens. A new method for detecting lens defects in security lens is presented in this paper. In the dark environment， backlight and ring light are used to strike the test lens respectively， and then the object square telephoto lens is used to image the high-resolution CMOS detector to take the head-on defect images of the lens to be tested. The results of the test show that the accuracy of the system is up to 90%， and it has a certain guiding role in the research on the automatic detection of industrial security lenses and the detection of optical instruments.

Because of the temperature changing， the image quality of IR cameras becomes worse. In order to prevent temperature-influence， a new mechanism of temperature-influence prevention is provided in this paper. It is based on lever principle to amplify the D-vale of different metals’ swelling value， and drive the lens to prevent the temperature-influence for IR optical system. The design programme， the parts’ key-design technology， and the design example of a guidance head are introdued. From -45~+60 ℃， the example’s drift value is 0.717， but it becomes 0 after temperature-influence is prevented. The experiments show that it is a new way for infrared athermalization.

Temperature changes will have an impact on the imaging quality of the optical system， and this impact is particularly obvious in the infrared band. The changes of the optical system material’s refractive index， spherical curvature and other parameters affected by temperature are analyzed in this paper. According to the principle of optical passive athermalization，an infrared optical system with a working band of 3~5 μm， a focal length of 30 mm， and F#=4 is designed. The pixels of cooled detector are 640×512 and the single pixel is 15 μm. The system adopts a four-piece structure， using two common mid-wave infrared materials， silicon and germanium， to meet the requirements of athermalization and achromatic aberration. It can maintain excellent performance in the operating temperature range of -30~+60 ℃. The image quality meets the requirements of the refrigerated mid-wave infrared system.

Perovskite solar cells have received great attentions as the next-generation photovoltaic device and the power conversion efficiency undergoes a continuous increase. The optoelectric properties of perovskite solar cells not only intimately connects to the perovskite film， but also has a direct connection with the device structure， interface， and the optical design. In this paper， our attention is focused on the surface optical properties. By introducing an antireflection layer on top of perovskite solar cells， it is anticipated to lower the reflection loss at the surface and enhance the power conversion efficiency. After studying the effect of microstructure on the transmittance， it is found that the antireflection layer with grating pattern can further increase the transmittance. Experimental results show that the introduction of antireflection layer can to some extent boost the power conversion efficiency of perovskite solar cells. At last a brief discussion about the involved mechanism of antireflection layer is provided.

The uniformity of the film thickness of the aluminum film deposited by the thermal evaporation of the 1.1 m large-diameter coating machine is studied. For the rotating plane fixture， the influence of the fixture height H and the distance L between the evaporation source and the central axis of the vacuum chamber on the uniformity of the aluminum film thickness is analyzed. When L=400 mm and H/L=1.10， the film thickness uniformity is the best， the unevenness is 9.614%， and the unevenness increases as the value of H/L increases. When H=500 mm and H/L=1.47， the film thickness uniformity is the best， the unevenness is 4.487%， and the unevenness increases as the value of H/L decreases. Furthermore， a modified baffle function is introduced， and a suitable correction mask is proposed and designed. The film thickness uniformity is improved from 17.8% without the correction mask to 3.9%， thereby solving the problem of aluminum film thickness uniformity.