A Study of Optical Diffraction Patterns: Guide to Practical Demonstrations Using Sieves for TEM Training
THE MICROSCOPE
2026, Volume 73:1, pp. 13–21
DOI
https://doi.org/10.59082/GCYE9458
AUTHOR
James R. Millette and Steven P. Compton
ABSTRACT
Thomas Young performed his famous double-slit diffraction experiment in 1801 in which he concluded that light propagated as a wave. The optical diffraction formula credited to Joseph von Fraunhofer for his work with diffraction gratings in 1821 is given by nλ = d sin (θ), where: n is the integer order of the fringe, λ is the wavelength of the light, d is the grating spacing, and θ is the angle of incidence from diffracting grating to the diffraction fringe pattern on a screen. A sieve that has been manufactured to ASTM standards produces a two-dimensional optical diffraction pattern that forms as an interference pattern of diffraction from multiple point sources.
The experiment described in this article was performed using four new sieves (200-, 325-, 400-, and 500-mesh) and one clean, used sieve (60-mesh). A 650 nm red laser was used as a source for all 5 sieves. The d-spacing of the various sieves, which is called the "pitch," aperture/hole (opening) plus the wire/bar, was calculated from the optical diffraction equation using the wavelength of the laser light, diffraction pattern measurements, and the distance from the sieve to the wall. For each sieve, the pitch was also estimated from a simple equation involving the mesh value and from estimated ranges (minimum and maximum) of standard values published in ASTM E11-22; Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves.
Only complete issues for this publication year are available for $25 each, plus shipping; individual articles are not for sale. To request a complete issue, or for any other inquires, please send email to themicroscope@mcri.org.
Shipping: Unless you specify otherwise, the shipping will be 3-5 day Priority Mail through the United States Postal Service.