Method for Controlling Stray Light

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The above images shows a redesigned baffling method for controlling stray light within a collimator. Previous collimator designs for this family of systems had issues with ring shaped reflections appearing in the presented image, decreasing overall system performance. A rethought baffle design was needed.

Design

Based on the prescription of the test unit, a range of 'controlled angles' was determined. The baffle design only controls stray light within these 'controlled angles', measured from the front field stop of the collimator to the entrance pupil of the test unit. Rays were then traced iteratively based on this control angle to determine optimal baffle positions and sizes back to the opposing barrel end.

The baffles were created using a stack of controlled height spacers and 50μm photo etched stainless steel to create close to knife-edge baffles. Performance of the new baffle design was a significant improvement over the old, while maintaining ease of assembly and reasonable cost on a low volume production scale.