Absolute angular position measurement by dual-comb spectroscopy of an autocollimation diffracted beam

Abstract

The dual-comb technique is a powerful tool in industrial inspection and scientific research and is capable of realizing ultrahigh-resolution and fast broadband spectral measurements. We propose an absolute angular-position measurement method based on dual-comb spectroscopy. With a simple layout, the absolute angular position can be naturally determined through the traceable and wide-amplitude spectra of the autocollimation diffracted beams of the target grating. We experimentally demonstrate that a precision of 0.12 arcsec in the dynamic range of approximately 6660 arcsec, along with a 1 kHz repetition rate difference, is achieved. Compared with a commercial autocollimator, over 1000 arcsec, the comparison residuals are kept within ±0.3 arcsec.

Optical Angle Barcodes Enabled by a Pixelated Metasurface for Absolute Micro‐Angle Measurement

“…Some people have also proposed some improvement schemes, such as using diffraction grating, [9] or cube corner [10] instead of flat mirror at the target end, and using femtosecond mode-locked laser instead of traditional visible laser [11][12][13] etc. The femtosecond laser autocollimator scheme using a diffraction grating as a reflector and an optical frequency comb (OFC) as a laser source solves the problem of direct sensitivity to angles, [14,15] realizes absolute angular position measurement, and achieves high-precision and wide-range. The introduction of the grating reflector enables the separation of OFC frequency components, converting the measured angle into optical frequency for digital output.…”