Skip to main content
U.S. flag

An official website of the United States government

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.

Geometric contributions to chopper wheel optical attenuation uncertainty



Matthew T. Spidell, Joshua A. Hadler, Michelle S. Stephens, John H. Lehman, Paul A. Williams


Calibrated reflective optical choppers are used in NIST’s high power laser calibration services due to their advantages in performance and safety over wedges and semi-transparent materials for beam power reduction. While the design, operation, and calibration of such choppers is generally straightforward, fabrication tolerances and edge geometry must be taken into account for low transmission (


attenuation method, optical power calibration, radiometer, calorimeter, chopper wheel, high power laser


Spidell, M. , Hadler, J. , Stephens, M. , Lehman, J. and Williams, P. (2017), Geometric contributions to chopper wheel optical attenuation uncertainty, Metrologia, [online], (Accessed April 14, 2024)
Created December 9, 2017, Updated November 10, 2018