Align a Linear Polarizer's Axis to be Vertical or Horizontal to the Table | Thorlabs Insights

The beam paths through many optical setups are routed parallel to the optical table. When this is the case, the plane of incidence and the p-polarization are typically oriented parallel to the table's surface, while the s-polarization is perpendicular. Therefore, polarizers aligned to pass p- or s- polarized light effectively have their axes aligned to be parallel or perpendicular, respectively, to the table's surface.

A procedure for optically aligning the axis of a polarizer to be perpendicular to the optical table is discussed and demonstrated using optical power readings of light transmitted through the polarizer. Then, three options for aligning the axis of a polarizer to be parallel to the table are outlined. The method of crossed polarizers is demonstrated. Tips and tricks for obtaining more precise measurements are also shared.

0:00 - Introduction
0:40 - Plane of Incidence at a Polarizing Beamsplitter
1:45 - Polarization Beamsplitter Can be Quick to Set Up
2:32 - Approach to Align Linear Polarizer Axis Vertical
3:40 - Vertical Alignment of Linear Polarizer Axis
8:46 - Options to Align a Linear Polarizer Axis Horizontal
9:50 -Crossed Linear Polarizers Alignment Method

Components used in this demonstration include:
- PL202 Collimated Laser Module: https://www.thorlabs.com/newgrouppage...
- Polarizing Beam Splitter: https://www.thorlabs.com/navigation.c...
- Linear Polarizers: https://www.thorlabs.com/navigation.c...
- Precision Rotation Mounts: https://www.thorlabs.com/newgrouppage...
- S120C Optical Power Sensor: https://www.thorlabs.com/newgrouppage...
- PM400 Optical Power Meter: https://www.thorlabs.com/newgrouppage...
- R2T post collar: https://www.thorlabs.com/newgrouppage...
- BHM1 Ruler: https://www.thorlabs.com/thorproduct....

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