Novel nano-scale absolute linear displacement measurement based on grating projection imaging. (September 2021)

• Record Type: Journal Article
• Authors: Yu, Hai; Wan, Qiuhua; Mu, Zhiya; Du, Yingcai; Liang, Lihui
• Is Part Of: Measurement. Volume 182(2021)
• Publication Date: 2021-09
• Subjects: Image-type displacement measurement -- High resolution -- High precision -- Grating projection imaging; Weights and measures -- Periodicals; Measurement -- Periodicals; Measurement; Weights and measures; Periodicals; 530.8
• DOI: 10.1016/j.measurement.2021.109738
• Languages: English
• ISSNs: 0263-2241

Abstract

Highlights: We propose a novel nano-scale absolute linear displacement measurement based on image recognition method. We use a linear array image sensor to recognize the coding pattern on the grating and then realize the decoding. We propose a high-resolution subdivision algorithm based on the location de-noising and fusion operation. We set up an experimental system and test the performance of the proposed algorithm. Abstract: There is urgent demand for new absolute Linear Displacement Measurement (LDM) technology with high resolution and high precision, during the development of high-end numerical control technology. In previous research, we found that displacement measurement based on the image processing method performs well, however, the volume increases when using an imaging lens, and the system is susceptible to factors such as virtual focus. In this paper, the lensless LDM image optical path is established based on grating projection imaging, then the absolute grating coding method is operated based on M −sequence pseudo-random coding. A linear displacement subdivision algorithm is then deployed based on the digital image recognition algorithm. An LDM device with a measuring range of 250 mm was designed to test the performance of the proposed method. The device shows a measurement resolution of 1 nm and measurement accuracy of 1.76 μ m in the range of 250 mm . This work lays a foundation for further research on high performance LDM technology.