Precision issues in angle measurements by means of autocollimator

Filatov, Yu. V.; Larichev, R. A.

doi:10.1117/12.2075598

Cited by 3 publications

(1 citation statement)

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“…It is imperative to minimize the noise level of the sensor signal in order to achieve high-resolution angular displacement measurement [ 206 , 207 , 208 ]. The method of self-collimation has maintained enduring popularity and continues to be utilized, with the development of numerous diverse variations over time [ 171 , 173 , 178 , 209 , 210 , 211 , 212 , 213 , 214 , 215 , 216 , 217 , 218 , 219 , 220 , 221 , 222 , 223 , 224 , 225 , 226 , 227 ]. The detection units are CCDs (Charge Coupled Devices) [ 228 , 229 ], QPDs (quadrant photodiodes) [ 230 , 231 ], and PSDs (position-sensitive detectors) [ 64 , 232 , 233 ].…”

Section: High Precision With Multiple Axesmentioning

confidence: 99%

A Review: High-Precision Angle Measurement Technologies

Wang,

Ma,

Cao

et al. 2024

Sensors

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Angle measurement is an essential component of precision measurement and serves as a crucial prerequisite for high-end manufacturing. It guides the implementation of precision manufacturing and assembly. The current angle measurement methods mainly focus on multiple axes, high precision, and large measurement ranges. This article introduces the technology of angle measurement from the perspectives of single-axis and multi-axis measurement schemes. Firstly, the single-axis measurement scheme is primarily achieved through optical methods, such as encoder discs that measure energy changes and interferometric phase changes, as well as mechanical, electromagnetic, and inertial angle measurement methods, among which interferometric methods offer the highest accuracy, with high cost, and encoder discs provide the largest measurement range with an ordinary price. Secondly, in the multi-axis measurement scheme, autocollimation instruments, including plane mirrors, gratings, and self-designed targets, are the main options. Although grating encoders can achieve three degrees of freedom in angle measurement with an ordinary price, they are limited in terms of measurement range and sensitivity compared to self-designed targets. Lastly, artificial intelligence assistance precision measurement is increasingly being embraced due to significant advancements in computer performance, making it more convenient to identify the relationship between measured values and detection values. In conclusion, angle measurement plays a crucial role in precision manufacturing, and the evolving and improving technologies provide the manufacturing industry with greater choices. The purpose of this review is to help readers quickly find more suitable technical solutions according to current application requirements, such as single/multiple axes, accuracy level, measuring range, budget, etc.

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Section: High Precision With Multiple Axesmentioning

confidence: 99%

A Review: High-Precision Angle Measurement Technologies

Wang,

Ma,

Cao

et al. 2024

Sensors

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Astigmatism analysis and correction method introduced by an inclined plate in a convergent optical path

Zheng

Tianxiang

et al. 2021

Appl. Opt.

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A plate beam splitter can simultaneously increase the transmittances and reflectances of different split spectrum segments. The splitter has been widely used in optical systems. However, when a beam passes through a beam splitter in a convergent optical path, the image quality may be degraded severely because the tilted plate may introduce aberrations such as astigmatism at the on-axis point. The formula for calculating this astigmatism is established. The calculated results are consistent with the simulated results, and the validity of the formula is verified through experiments. A cylindrical lens curvature calculation formula is derived to correct the on-axis astigmatism, which reduces the aberrations introduced by the tilted plate and improves the imaging performance. The imaging characteristics of the off-axis field of view and the reasons for the changes in image quality are analyzed. The F -number range of the converging light path is calculated, which provides a reference for tilted applications of flat-panel optical elements in converging light paths.

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Development of a wafer warpage measurement technique using Moiré-based method

et al. 2016

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This paper reports on a novel technique for measuring wafer warpage, using the design concepts of moiré shift, digital moiré, autocollimator, and the scanning profiling method. The measurement system is divided into two parts: an optical moiré system and a phase analysis system. The optical arrangement can be adjusted to control the projection of a linear grating image onto the surface of a wafer to be reflected back into a CCD camera. The grating image acquired by the CCD camera is used for measurement whereas a reference grating image is obtained using the digital moiré method. By overlapping the two images of the measurement and the reference gratings, the corresponding moiré fringes are formed. The phase of the moiré fringes will change proportionally to the degree of warpage in the wafer, which can be measured by detecting variations in the phase shift of the moiré fringes in the scanning profile across the surface of the entire wafer. Measurement resolution can be controlled by adjusting the pitch size of the grating or the focal length of the focusing lens, or by adjusting the angle between the images of the measurement and reference gratings. Experiment results demonstrate that the proposed method is able to achieve an angular resolution of 0.2 μrad. As compared to the current warpage measurement techniques, the proposed method has the ability of high measurement resolution, high stability, and high flexibility.

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Precision issues in angle measurements by means of autocollimator

Cited by 3 publications

References 0 publications

A Review: High-Precision Angle Measurement Technologies

A Review: High-Precision Angle Measurement Technologies

Astigmatism analysis and correction method introduced by an inclined plate in a convergent optical path

Development of a wafer warpage measurement technique using Moiré-based method

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