Heterodyne common-path grating interferometer with Littrow configuration

Abstract

This paper presents a heterodyne common-path grating interferometer with Littrow configuration (HCGIL). The HCGIL can effectively overcome environmental disturbance effect and the DC offset and the amplitude variation of the measurement signals. Experimental results match well with the HP5529A results for long-range measurements. Results also show that the estimated measurement resolution is 0.15 ± 0.027 nm. The stability of the HCGIL is -0.41 ± 0.23 nm. Therefore, the HCGIL has potential for subnanometer resolution and long-range applications.

A new high-precision device for one-dimensional grating period measurement

“…As important tools for precision measurement, grating interferometer and laser interferometer have submicron resolution and accuracy. Among them, laser interferometer uses the wavelength in air as the measurement reference [3][4], and grating interferometer measurement mechanism mainly includes two types: stripe projection principle and interferometric principle [5][6]. The core element of grating interferometer is grating, with grating distance as the reference, compact structure, symmetric optical path, short optical range and low sensitivity to external environment, which can be applied to multi-dimensional precision displacement measurement.…”

Multi-dimensional grating interferometer based on fibre-fed measurement heads arranged in Littrow configuration

“…An interferometric encoder in a Littrow configuration based on the autocollimation principle and phase shifting technique was developed for displacement measurements and presented by Kao et al An error of 53 nm for this encoder was determined in the 100-mm measurement range [6]. Wu et al developed a heterodyne commonpath grating interferometer with a Littrow configuration that has a resolution of 0.15 ± 0.027 nm [7]. Another approach was realized by Lu et al, using a symmetric Littrow configuration for two interferometric modules in order to detect…”

Symmetrical short-period and high signal-to-noise ratio heterodyne grating interferometer

“…Both homodyne-and the heterodyne-type GIs have been proposed for displacement measurement. With the introduction of a carrier, heterodyne grating interferometers (HGIs) overcome the direct current offset and the amplitude variation of the measurement signals that the homodyne type always encounters [9] . Lee et al first proposed a HGI with subnanometric resolution [10] ; then, they introduced the shearing interferometry into HGIs for long-range applications [11] .…”

“…Lee et al first proposed a HGI with subnanometric resolution [10] ; then, they introduced the shearing interferometry into HGIs for long-range applications [11] . Wu et al presented a HGI with a double-diffraction arrangement that can effectively compensate the head-to-scale error [5] , then developed a common-path HGI with a Littrow configuration to further improve the resolution and stability [9] . Hsieh et al proposed a HGI with a quasi-common-optical-path configuration [12] .…”