Interferometer adopting a ball lens both as a beam collimator and a reflector

Abstract

We aim to develop an alignment monitor, which consists of a length measurement grid of absolute distance interferometers, where we adopt a ball lens both as a beam collimator and a reflector. Collimated beams by the ball lenses were evaluated to have clear 2-dimensional circular gaussian distributions with their diameters, divergence angles and maximum waist distances agreeing well with their estimated values. An interferometer, which adopts a ball lens both as a collimator and a reflector, were evaluated to have uniform sensitivities against distances from several 10 mm to around 1000 mm, and tolerances against the target offsets of more than ±0.5 mm for the direction perpendicular to the measurement direction. These results show that the ball lens can be adopted for our alignment monitor both as a collimator and a reflector.

Keywords

• Ball lens
• Collimator
• Retroreflector
• Interferometer
• Optical frequency comb