Free-standing wire-grid polarizers: measurement & handling
Practical recommendations for safely handling, installing and characterising Purewavepolarizers free-standing terahertz wire-grid polarizers.
Protect the free-standing wire grid
Handle the polarizer only by its outer frame. Never touch, wipe or apply pressure to the wire grid.
Handling a free-standing wire grid
Hold the frame only
Keep fingers and tools clear of the aperture.
Keep the grid covered
Return it to its protective packaging when not installed.
Never wipe the grid
Do not use conventional optical cleaning methods.
Ask before cleaning
Contact Purewavepolarizers if the grid becomes contaminated.
Installing and orienting the wire-grid polarizer
Correct installation ensures reliable results
Follow these key points when installing the polarizer in your terahertz system.
- Handle and secure the outer frame only.
- Centre the beam within the clear aperture.
- For standard measurements, position the grid normal to the optical axis.
Recommended measurement arrangement
1
Use a collimated beam
Ensure the beam is approximately collimated at the polarizer position.
2
Avoid clipping at the aperture
Keep the beam diameter smaller than the clear aperture.
3
Do not disturb the alignment between reference and sample scans
Maintain the same optical arrangement for reference and sample measurements.
Reliable characterisation
Finding the true minimum
- Scan through the nominal minimum.
- Use finer angular steps close to the minimum.
- Measure on both sides and fit the response.
- Record the detector noise floor.
Control water vapour
- Purge as much of the THz path as practical.
- Allow conditions to stabilise before measurement.
- Use identical conditions for reference and sample scans.
- Record the purge conditions or relative humidity.
Measurement checklist
- Part number
- Reference method
- Wire orientation
- Purge conditions
- Angle of incidence
- Angular step size
- Beam diameter
- Averaging
- Frequency range and resolution
- Detector noise floor