Robust and precision small-angle measurement through the speckle pattern imaging technique

With technological advancements in various fields, the precision estimation of small angles is becoming crucial in many scientific, engineering, and metrology applications. Traditional mechanical and electromagnetic methods face limitations in automation and precision when measuring small angles, while optical techniques such as interferometers and autocollimators offer high sensitivity and accuracy but suffer from complexity and instability. Speckle pattern-based techniques have thus emerged as promising alternatives, offering high sensitivity and non-contact measurement capabilities. This paper presents a robust and precision small-angle measurement technique utilizing speckle patterns. For demonstration, an experimental setup, featuring a CMOS (complementary metal-oxide-semiconductor) camera and a motorized stage, is developed alongside an algorithm for angle estimation. Mathematical analysis and experimental validation confirm the method's accuracy and preciseness, while repeatability testing confirms its robustness. The method's simplicity, reliability, and compatibility with small spaces make it a valuable tool for various applications where precision small-angle measurement is required.