Uploaded December 2021 | Updated September 2026, 1 hour ago

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Off-Axis parabolic (OAP) mirrors are often used to collimate divergent beams, but aligning these mirrors can be a frustrating experience. This is because there are multiple variables that must be controlled during the alignment process. This demonstration divides the procedure into discrete steps and includes helpful tips for successfully positioning the mirror and light source. In addition, the dependence of the correct alignment on the mirror's geometry is discussed, and the typical effects of different misalignment geometries on the beam shape are shown on a viewing screen.

In this demonstration, the divergent output of an optical fiber and an OAP mirror are aligned so that the incident light and the collimated reflected beam travel in a plane parallel to the surface of the optical table. Because of this, an important initial step in the procedure is to set both the height of the source and the center of the mirror mount's bore at the height of the desired collimated beam. Then, an iterative approach is used in which the mirror is rotated to bring the plane of reflection parallel to the plane of the table, and the fiber's end face is moved to the mirror's focal point.

00:00 - Introduction
01:00 - Alignment and the Parent Parabola
02:12 - Attach the Adapter to the Mirror
02:55 -Mount and Coarsely Align the Mirror
04:58 - Set Mirror and Source Heights to be Equal
05:39 - Initial Positioning of Mirror and Source
07:20 - Fine Positioning of Mirror and Source
10:37 - Beam Quality, Options, and Having Patience

Key Components used in this Demonstration Include:
- MPD149-F01-Off Axis Parabolic Mirror, Ø1", 90°, RFL = 4": thorlabs.com/newgrouppage9.cfm?objectgroup_id=7002&pn=MPD149-F01&YVI=18
- SM1MP SM1 Adapter for Ø1" Off-Axis Parabolic Mirror: thorlabs.com/newgrouppage9.cfm?objectgroup_id=5447&pn=SM1MP&YVI=18
- KC1-T Kinematic SM1-Threaded Mount: thorlabs.com/newgrouppage9.cfm?objectgroup_id=185&pn=KC1-T&YVI=18
- R2 Post Collar: thorlabs.com/newgrouppage9.cfm?objectgroup_id=2003&pn=R2&YVI=18

Other Components Include:
- M625F2 Fiber Coupled LED: thorlabs.com/newgrouppage9.cfm?objectgroup_id=5206&pn=M625F2&YVI=18
- LEDD1B T-Cube LED Driver: thorlabs.com/newgrouppage9.cfm?objectgroup_id=2616&pn=LEDD1B&YVI=18
- M15L01 SMA-SMA Fiber Patch Cable: thorlabs.com/newgrouppage9.cfm?objectgroup_id=351&pn=M15L01&YVI=18
- LMR1 Lens Mount: thorlabs.com/newgrouppage9.cfm?objectgroup_id=1433&pn=LMR1&YVI=18
- SM1SMA SMA Fiber Adapter Plate: thorlabs.com/newgrouppage9.cfm?objectgroup_id=69&pn=SM1SMA&YVI=18
- EDU-VS2 Smaller Viewing Screen: thorlabs.com/newgrouppage9.cfm?objectgroup_id=7489&pn=EDU-VS2&YVI=18
- EDU-VS1 Larger Viewing Screen: thorlabs.com/newgrouppage9.cfm?objectgroup_id=7489&pn=EDU-VS1&YVI=18
- BHM3 Ruler: thorlabs.com/newgrouppage9.cfm?objectgroup_id=7243&pn=BHM3&YVI=18
- SPW602 Spanner Wrench: thorlabs.com/newgrouppage9.cfm?objectgroup_id=1430&pn=SPW602&YVI=18
- BM075 Magnetic Button Clamps: thorlabs.com/newgrouppage9.cfm?objectgroup_id=2685&pn=BM075&YVI=18
- HW-KIT2 1/4"-20 Cap Screw and Hardware Kit: thorlabs.com/newgrouppage9.cfm?objectgroup_id=248&pn=HW-KIT2&YVI=18

For more photonics how-to videos, visit thorlabs.com/newgrouppage9.cfm?objectgroup_id=14062&YVI=18