Optical bench assembly for the near-infrared camera

Abstract

The Near Infrared Camera is the primary imaging instrument on the James Webb Space Telescope. This instrument operates in the wavelength range of 0.6 to 5 microns and at a temperature of 35K. Two mirror-image optical paths or modules are utilized to provide two adjacent fields of view for science observations and redundancy for the purpose of wavefront sensing. All optical components are supported and aligned by an Optical Bench Assembly consisting of two benches mounted back to back. Each optical bench is a closed back Beryllium structure optimized for mass and stiffness. The closed back structure is achieved by bonding two machined parts together at the midplane of the structure. Each bench half is an open back structure consisting of a facesheet with machined ribs optimized to provide stiffness and to support along primary load paths. The two benches are integrated with optical components separately and are subsequently joined by bolts and pins to form the Optical Bench Assembly. The assembly is then mounted to interface struts, which are used to mount the instrument within the Integrated Science Instrument Module for integration into the JWST observatory. The design of the Optical Bench Assembly is describing including trade studies and analysis results.