Module ‐ Doublepass Baseplate
Modular Double Pass AOM (Acousto-Optic Modulator), (aka doublepass), uses an acousto-optical modulator to diffract a laser beam twice. This is achieved by using a retroreflection mirror to send the modulated light back through the AOM for a second modulation. The angle shift introduced by the first pass is canceled, and the modulation frequency range is effectively doubled. This configuration is commonly used in Atomic, Molecular, and Optical (AMO) physics experiments.
The CAD design includes the following components:
- Pair of input mirrors.
- Half-wave plate (to control power to plate)
- Polarizing Beam Splitter (PBS) cube
- Acousto-Optical Modulator
- Lens (focal length from AOM)
- Quarter-wave plate to rotate the polarization of the light 1/4 once on each pass, allowing it to pass through the PBS.
- Iris to block zeroth-order light
- Retro-reflection mirror (focal length from lens, 2 focal lengths from AOM)
- Pair of output mirrors
- Fiber port output to system.
- The lens should be positioned between the AOM and the retro mirror, a focal length from each.
- The quarter-wave plate should be placed between the retro mirror and the lens to minimize reflections from the lens surface, which could cause unwanted light leakage when the beam needs to be turned off.
- The iris should be carefully positioned to completely block the zeroth-order light, ensuring that only diffracted light is transmitted.
