Researches On Auto Grating Diffraction Intensity Detecting System With CCD Image Recognition

Grating is an important component in optical instruments and optoelectronics information processing systems, and the diffraction efficiency is one of the most important parameters in grating-evaluating. At present, more and more CCD devices take part in optoelectronics detecting instruments for their advantages such as wide dynamic range and high sensitivity. The automatic intensity detecting system introduced in this paper is a novel application with CCD device in the area of grating diffraction efficiency. The main results are achieved in this paper are as follows:The influence of random noise in CCD image-collection is analysed experimentally. From the experimental results, several methods are presented to eliminate the effect of noise in the testing software design: collecting images sequentially and take the average gray value as results; setting division threshold appropriately; and adopting more stable recognition arithmetic.A novel region recognition arithmetic based on object centre is presented in this paper. Firstly, the object center is to be decided, then transverse span and longitudinal span of the object are scanned and marked. This arithmetic is suitable to recognize simple objects in dark background. With different kinds of objects, the arithmetic to find the object's centre may have some different.The experimental comparisons have been made between image recognition with different arithmetic, the outcomes show that this novel arithmetic (Region Recognition Arithmetic Based on Object Centre) can simultaneously recognize several objects accurately and quickly with high distinguish efficiency and strong aims. This arithmetic doesn't change gray value of pixels, so that it will never bring error to light intensity measurement.Comparisons between several diffraction efficiency measurement systems are made experimentally, the results presented in this paper show that they are more close to the theoretic values and that the novel measure provides more parameters for grating quality-evaluation.The automatic light intensity detecting system proposed in this paper is closely combined with the second development of video card's dynamic link library under the VC programming conditions. It fits the quality evaluation of numbers of gratings and has friendly interfaces as well as very fast running speed.