Sensors for Space Telescope Lens Testing

Sensors for Space Telescope Lens Testing

The Euclid Satellite project a good example of how Philtec’s sensors are being used with excellent results in cryogenic conditions.

This month Philtec again delivered sensor systems for space telescope lens distortion measurements. These are 2-channel fiber optic displacement sensor systems (see image above) designed for 3.2 mm operation in vacuum.

Seven 2-channel sensor systems were delivered with the following options:

  • Multi-Channel Vacuum Passthru Assembly in 120 mm Custom Flange
  • SS Interlock Cable Jacket in Vacuum
  • 6 m Total Fiberoptic Cable Length (1.5 m in air, 4.5 m in vacuum)
  • Low CTE Invar Tips

The fiber optic cables are trifurcated for connection to the vacuum passthru (one transmit bundle and two receivers). With 14 sensor channels x 3 legs each, 42 vacuum ports were required. Each BvF120 has 16 ports, and therefore three BvF120 assemblies were used to pass all channels (see image below).

Multi-Channel Vacuum Passthru Assembly image

A technical paper published in 2012  shows how Philtec’s high precision sensors were successfully used at 150°K to verify the distortion of lens holders to be <1 micron, well within the project requirements.


‘Test Results of High-Precision Large Cryogenic Lens Holders’, 2012, Proceedings of the SPIE Publication “Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II”.

Blog, Detectors, Fiber Optics