| Conventional photoelectric autocollimation usually choose CCD sensor asphotoelectric conversion device, which have some disadvantages such as high powerconsumption, complicated driving circuit and low frame rate etc. Recently, with thedevelopment of technology of VLSI, CMOS image sensor integrates the functions ofA/D converting, signal processing, gain controlling, precision amplifying and datastoring and so on, this greatly improves the integration degree of system.In this thesis, CMOS Image Sensor is used as the imaging device of twodimensional photoelectric autocollimation. The article focuses on improving accuracyand measuring speed of autocollimation, and some critical technologies were introducedin detail.The paper analyze the sensor performance and put it into actual measuringcombine the autocollimation’s feature. The research result of the thesis are as follows:1. The paper analyzed and discussed sub-pixel in theory, introducing a improvedWeighted centroid localization algorithm. The algorithm can adjusted thethreshold automatically based on the change of image gray value, which has theself-adaptability. Photoelectric autocollimation’s measure accuracy has beenimproved to0.23, which achieve the aim for high accuracy measurements.2. Propose a method of sub-region measuring, which based on CMOS ImageSensor’s ROI(Region Of Interest) function, and ensure that improve the measuringspeed in the condition of changing the size and location of pixel reading window.The measuring speed of system increases from27.5fps to110fps through the ROI.3. A module of adaptive exposure controlling is designed, which can carry outintegration adjust according to the change of light energy.4. The paper has study in CMOS image sensor’s multiple slope integration, thesensor’s optical dynamic range is expand through the operation of multiple slopeintegration, and the S/N (signal to noise ratio) of system corresponding improved greatly.5. Experiments are performed to testify the engineering sample of photoelectricautocollimation, the experiment results indicate accuracy of angle measurementfully satisfies the requirements by autocollimation. |
