Chromium Self-Traceable Length Standard: Investigating Geometry and Diffraction for Length Traceability Chain

TL;DR

This paper investigates the geometric and diffraction properties of a chromium grating, fabricated via atom lithography, to enhance its role as a self-traceable length standard in nanometric metrology, linking measurements to fundamental constants.

Contribution

It analyzes and engineers diffraction characteristics and polarization effects of chromium gratings to improve their application as self-traceable length standards in traceability chains.

Findings

Fabricated chromium gratings with precise pitch using atom lithography.

Characterized diffraction performance and polarization effects.

Verified length measurement capabilities in a self-traceable interferometer.

Abstract

Natural constant-based metrology methods offer an effective approach to achieving traceability in nanometric measurements. The Cr grating, fabricated by atom lithography and featuring a pitch of $d=212.7705\pm0.0049~{\rm nm}$ traceable to the Cr transition frequency $^{7}S_{3}$ $\rightarrow$ $^{7}P_{4}^{0}$, demonstrates potential as a self-traceable length standard in nano-length metrology by grating interferometer. This research aims to analyze and engineer the diffraction characteristics that enhance the Cr grating as a self-traceable length standard within the length traceability chain based on the Cr transition frequency. Accordingly, we investigate the geometric morphology and diffraction characteristics of the Cr grating, analyzes the influence of the grating's polarization-sensitive characteristics on the Littrow configuration grating interferometer, and establishes the criteria for Cr grating fabrication. Experimentally, we fabricate an expanded Cr grating by scanning atom lithography, characterize its diffraction performance, and conduct preliminary verification of length measurement in a self-traceable grating interferometer. This work adheres to the international trend of flattened metrology development, offering a valuable reference for advancing subsequent metrological technologies throughout the new traceability chain.