Analysis of signal characteristics of novel grating displacement sensor based on infrared LED

Abstract

With the rapid development of precision automation and intelligent equipment industry, the need of miniaturized and high-precision grating displacement sensors is increasing. It is still a challenge for highly reliable mini sensors due to the limitations of current employed light sources, such as their sizes, features, etc. To develop novel grating displacement sensors, light source needs to be met the requirements. Based on the principles of grating signals, we developed a novel grating displacement sensor by employing a Honeywell infrared LED as the light source. The influence of the main parameters (e.g. divergence angle, width of light source, etc.) of the infrared LED light source on the grating Moiré Fringes has been analyzed in detail. The intensity distribution of the Moiré light field model has also been established to estimate the quality of the grating signals with new light source. Both mathematical modeling and experimental results verify the feasibility of the design showing two clear orthogonal sinusoidal signals. Compared with traditional light sources (visible point light source), the infrared LED light source can significantly shorten the grating optical structure, thereby facilitating the miniaturization of the grating sensor. Due to the transmission characteristics of long-wavelength light, the infrared source can both improve the contrast of the Moiré Fringes and the quality of the grating signals. We believe that the designed grating displacement sensor will open a new phase in application with the advantages of infrared LED source, such as stable intensity, long lifetime and low prices.