A bonded precision optical assembly using potassium hydroxide

The pupil imaging lens (PIL) assembly is one component within the NIRCam instrument, which is the primary imaging instrument on the James Webb Space Telescope (JWST). The main purpose of the PIL assembly is to form an image of the eighteen primary mirror segments of the JWST onto the NIRCam focal plane arrays (FPAs). NIRCam is the only instrument on the JWST observatory with wave front sensing (WFS) capability, and will use the PIL in conjunction with the WFS measurements1. The purpose of this paper is to introduce the audience to a monolithic PIL assembly created from five unique lenses mounted to an optical baseplate. The lenses are assembled using a direct bonding method, with the aid of a diluted potassium hydroxide solution. Described in this paper is a simple, yet precise method for aligning and assembling the PIL optics.