A new arrangement method for photoelectric cells and its application

摘要

Traditional photoelectric detection methods consider the interference fringes are evenly intensity distributed without random noise and the photoelectric signal satisfies the requirement of counter and subdivision in theory. However, in order to improve the Signal-to-Noise Ratio of detection, not only the requirement of counter and subdivision, but also the space arrangement of photoelectric cells must be taken into account. This paper presents a new arrangement method of photoelectric cells. The four adjacent photoelectric cells of the new method are arrayed in a square photoelectric cell array that inclines from the direction of the interference fringes with a certain offset angle. The new method and the traditional method are analyzed by integral equations and three models of random noise, AC amplitude and DC adrift are founded in this paper. According to the theoretical and experimental analysis, the detection Signal-to-Noise Ratio of the new method is improved remarkably compared with the traditional methods. This new method, which can dramatically restrain DC adrift of light intensity even if the fringes' signal is faint, can be applied in a laser-interference sensor for three-dimensional surface topography measurement.