Collimate a Laser with a Shear-Plate Collimation Tester (Viewer Inspired) | Thorlabs Insights

A shear-plate collimation tester is a compact shearing interferometer that is convenient for inserting into a beam path. When in place, the device can be used to test and optimize a laser beam’s collimation. This Video Insight demonstrates a technique for using the device, shares some troubleshooting tips, and provides guidance for determining whether the approach is a good option for testing the collimation of a particular beam.

The device can remain in the beam while the position of the collimating lens, which in this case is an achromatic doublet, is adjusted. Fringes visible on the ground glass diffuser, which is on top of the device, indicate whether the beam is converging, diverging, or collimated.

It should be kept in mind that this technique requires light with sufficient coherence, low wavefront aberrations, and a shear plate thickness compatible with the beam diameter. Note also that the distance over which a beam is collimated is never infinite, so the device should be located within approximately one Rayleigh range of the collimated beam's waist. (For more information, see https://www.thorlabs.com/newgrouppage.... )

Assistance is provided for diagnosing the problem when no interference fringes are visible, or the fringes are difficult to interpret. The demonstration shows when the solution is to use a thinner shear plate, to adjust the lens position, or to add a magnified viewer to the top of the device. It is also shown that a different method is required to test and optimize beam collimation when there are significant wavefront aberrations or an insufficient coherence length.

00:00 Introduction
00:34 Usage and Limitations
01:46 Collimation of Larger Beam
04:14 Beam Quality Comments & Demo
05:15 Collimation of Smaller Beam
06:52 Using a Magnified Viewing Screen
08:12 Best Use Summary

Components used in this Demonstration Include:
- Shearing Interferometers: https://www.thorlabs.com/newgrouppage...
- SIVS Magnified Viewer (for Shearing Interferometer): https://www.thorlabs.com/newgrouppage...
- PL202 Compact Laser Module: https://www.thorlabs.com/newgrouppage...
- AD11F Adapter (Laser to Mount): https://www.thorlabs.com/newgrouppage...
- KS1T Threaded Kinematic Mount: https://www.thorlabs.com/newgrouppage...
- Mounted Achromatic Doublet Lenses: https://www.thorlabs.com/newgrouppage...
- Plano-Convex Spherical Lenses: https://www.thorlabs.com/navigation.c...
- Ø1” Lens Tubes (Lens Housing): https://www.thorlabs.com/newgrouppage...
- CP33 Threaded Cage Plate (Lens Mount): https://www.thorlabs.com/newgrouppage...
- CPX1 Threaded Translating Cage Plate (Lens Mount): https://www.thorlabs.com/newgrouppage...
- Optical Rails: https://www.thorlabs.com/newgrouppage...
- Optical Rail Carriers: https://www.thorlabs.com/newgrouppage...
- Optical Posts, Ø1/2” and Ø12 mm: https://www.thorlabs.com/newgrouppage...
- Post Holders: https://www.thorlabs.com/newgrouppage...
- VC3C V-Groove Block: https://www.thorlabs.com/newgrouppage...
- TC4 Balldriver Caddy: https://www.thorlabs.com/newgrouppage...

For more photonics how-to videos, visit https://www.thorlabs.com/newgrouppage...