Key Engineering Materials Vol. 552

Abstract: The collimator is a kind of necessary optical instrument for camera in the assembly, adjustment, and test process. In order to meet the high precision camera test requirements within the temperature in a range of 20°C±10°C, a set of off-axis aspherical collimator with high accuracy and high temperature stability is designed. Mirrors use silicon carbide materials. Collimator tube is made of Indium steel materials. After finite element analysis, difference value of the linear expansion coefficient kept within a certain range and reasonable reflector support and the collimator can keep accurate stability within a certain temperature range. After test, off-axis collimator with Ф400mm diameter and, 8m focal length at 20°C±10°C, the wavefront aberration is kept in the range from1/5λ（P-V, λ=632.8nm) to 1/30λ(RMS).The precision of the collimator can meet design requirement.

Abstract: This paper reaches a detection system which use for detecting the three-axis consistency of optical collimator basing on equivalent method. Describing the detect principle and calculating the offset of the image of optical path caused by spectroscope via anglicizing of optical system. Meanwhile, it uses zemax to simulate the offset of optical path. After adjusting the structure of the system, the detection system is calibrated by theodolite whose accuracy is 0.5″. The experiment result shows that the measurement error of the optical axis consistency <0.05mrad.

Abstract: Polarization imaging technology that is on the basis of the polarization measurement can change the obtained polarization information into two-dimensional image, from which we can acquire polarization characteristics of target scene just like normal gray image so that this technique is widely used in the fields of military investigation, medical testing, space exploration, meteorology and so on. Traditional imaging polarimeter is time sequence polarization imaging, which is to use sequential rotational polarization components (line polarizer or wave plate etc.) and to combine Fourier analysis method to acquire final Stokes components. But because of the sacrificing of temporal resolution, this technique does not meet the needs of the situation of high-speed dynamic changing scene. While current simultaneously polarization imaging technique commonly uses multiple sets of optical systems and at least four CCD cameras, which have the problems of low energy utilization rate and non-matching performance among the optical sets. To solve the aforementioned problems, we design and implement a set of non-mechanical rotating parts, double Wollaston prisms-based high resolution simultaneously imaging polarimeter. This system uses the specific combination of non-polarizing beam splitter, Wollaston prisms and wave plates to divide the incident target space beam into four optical paths of different polarization states which can be taken into two types: two paths in the reflection part and two paths in the transmission part. Finally the imaging lens converge the beam to different regions of two large array CCD to image four images. To achieve the goal of extracting complete Stokes information, we apply the Stokes vector and Mueller matrix analysis. The article presents systems structure, working theory, calibration method, experiment data analysis and system polarization performance, which provides a good reference for the simultaneously high-speed polarization imaging.

Abstract: A machine vision system for bearing outer diameter inspection has been developed in this paper. The infinite objective of optical system is applied to diameter measurement system. The paper provides a method for measuring the size of objects based on polynomial interpolation. The technology of CCD image stagger is applied in the paper. The method can avoid space between pixels astriction theoretically, so higher measurement accuracy is gained. The experiment results show that the system has many advantages such as non- touch , high speed and higher precision.

Abstract: This tester is mainly used to test the firepower of armored vehicles weapon equipment, the artillery loosening amount and rigidity of fire control system, the largest mobilization artillery speed and other related static parameters. In this paper, the design of the tester include: static parameters optical probe, the vehicle central control device, the image processing device, the test target and so on. In the static parameter tests of weapon systems, the static probe is installed in the muzzle, the prescriptive force is imposed on the artillery tube to produce movement, CCD camera can photography the relative motion image of the target, then the computer processes images according to the corresponding program, and figures out the trajectory of the artillery tube, thus the corresponding static parameters is calculated. Experimental results show that: The system has reached a very good image quality, and the reliability is very high, Diagonal field of view>4°, the specification requirements are reached.

Abstract: Endoscopic telecentric apparatus is a precision measuring instrument which consists of optical, mechanical and electrical technologies. It can be applied in real-time accurate test to detect the position, shape and wall surface defects of brake master cylinder. This paper designed an optical system with Zemax, it can be used in endoscopic telecentric apparatus. The system has 4mm linear field of view, the line of vision is 90°,the magnification is 0.75×,the depth of field is 6mm.The value of modulation transfer function (MTF) is close to the diffraction limit, the resolution of the system is up to 3 and the spot diagrams of all configurations are smaller than Airy disk, the total track is less than 300mm. It adopts 1/6CCD to receive image, the measurement accuracy reaches to 0.03mm.The system uses pentagonal prism to realize 90°line of vision, it is convenient to assemble and avoids the mirror image. The image quality is good and the design meets the requirement.

Abstract: Beam splitter is widely applied in many optical systems. The beam splitter is generally composed of many reflective mirrors and beam splitting prisms. The optical components can not reach the theoretical design state during assemble process. It must be solved through optical alignment. The mathematics model of alignment and error analysis for beam splitter are built in this paper. The effect of optical alignment error of beam splitter on optical system could be analyzed with this mathematical model. At the mean time, the mechanical alignment of beam splitter is directed to fast alignment in practical process. One kind of optical communication system is shown as example. The optical transmitting exit is commonly used. The requirement of axis parallelism of sub-systems is very strict. The axis parallelism between sub-systems reaches 5’’ in experiment with this model application.

Abstract: Based on theoretical analysis, the beam expender used in all fiber lidar with a coupling efficiency of single mode fiber (SMF) is investigated. Some numerical computations are carried out and following results are obtained. For all fiber lidar in order to get the maximum coupling efficiency on SMF, the relationship between the distance d, ranged from the secondary to primary lens of the beam expender, and the laser waist spot location l, which is at a distance from the secondary lens of beam expender are obtained. And also the relationship between l and the measurable bandwidth is analyzed. Under the condition that if the laser location is certain and the imagine spot location is infinite, with adjusting the distance d which can make the image spot size obtain its minimum, the maximum coupling efficiency about 70.6% is got and the adjusting range of d has only 0.2~0.9mm. Assuming that the image spot distance is infinite, and the minimum of spot radius is got after the laser waist spot goes through the beam expender, the function between d and l is retrieved by use of laser propagation theory. By comparing the theoretical curve with the computing one, the theoretical function agrees with the numerical computing curve approximately. These conclusions have the important directive significance for design of all fiber Lidar.

Abstract: Shortly after the invention of the laser, researchers began to dream of converting sunlight into laser radiation directly. A direct conversion of concentrated solar light into a coherent laser beam improved the conversion efficiency because of the simple design of the structure, which is an innovation in the new field of solar energy utilization. We utilize the Fresnel lens of 1m2 to collect solar light, which is coupled into the conical chamber pumping Nd:YAG crystal, in 5mm-diameter 80mm-length rod. The pumping cavity is designed to combine end-pumping with side-pumping, in which the pumping light comes from many directions. It could compensate the drawbacks of single end-pumping or side-pumping. In the experiment, we obtain the maximum laser output power of 2.5 W, with a slope efficiency achieving 1.3%. By the Tracepro ray-tracing software, simulating the incoming energy distribution in the focus of the Fresnel lens, the concentration ratio of 104 is achieved.

Abstract: Determination of parameters is presented in the modeling of Tm-doped fiber lasers. The thesis chooses parameters, numerical simulation to examine the performance of the laser system for different pump schemes and cavity parameters. Their impacts on the laser performance are discussed.