Research On Miniaturized Embedded Two-dimensional Autocollimator

The autocollimator is a precision measuring instrument which based on the optical imaging principle of self-collimated for the small angle measurement or can be converted to small angle measurement.At present,the optoelectronic autocollimators widely used need to communicate with the special host computer through the interface to complete the image data processing and measurement results display.In addition,it is difficult to complete the measurement task in some specific work sites such as small place due to its large size.Therefore,it is necessary to develop an integrated small autocollimator.In this paper," study on miniaturized embedded two-dimensional autocollimator ",a method of using highly integrated embedded control system instead of traditional host computer is proposed based on the research of autocollimator's design model and analysis of miniaturization caused by the design difficulties,the purpose of miniaturization is achieved by combining with the camera-type optical system,the optical machine-controlled integrated structure size of engineering prototype is not bigger than 200mm x 120mm x 80mm.The specific work done in this paper mainly has the following four aspects:1.The CMV4000 which is a kind of CMOS image sensor is used as a photoelectric conversion device,the CMV4000 drive and Serial and parallel conversion of output data from LVDS high-speed channel are completed in FPGA as well as the self-calibration.The parallel output of four data channels of the image sensor is completed through the ping-pong operation and the data pipeline processing and complete combination of data are realized.2.The highly integrated embedded control system based on FPGA is designed to achieve the image sensor drive,image data processing,misalignment angle calculation and data display and so on.The entire system does not require a special host computer and the difficulty of miniaturization is overcome.3.The adaptive exposure algorithm is presented.The electronic control system automatically adjust the internal parameters of the image sensor to control the exposure time to adapt to changes in light energy after comparison between real-time collection of image pixel data and gray value threshold.4.The method of piecewise linear calibration is presented,the horizontal direction equivalent and the vertical direction equivalent of 44×44 linear grids in the field of view are calculated respectively,and the miniaturized embedded two-dimensional autocollimator is calibrated.Test results show that maximum measurement error is 0.66" within the entire range and the measurement error does not exceed ±0.5" within any 20".The technical requirements are fully meet.