An official website of the United States government
Here's how you know
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
(a) Grayscale maps (30 to 150 grayscale levels) of a grating with a period of 400 μm (200 pixels in the horizontal direction) for the calibration; and (b) calibration curve between the exposure depth and grayscale level.