|
On this page:
Abstract
Supporting Materials
|
Abstract
Once the surfaces of a telescope are fabricated, an accurate metrology process must be available to ensure the optical and fiducial surfaces conform to the design specifications. This section describes metrology techniques for reflective optical systems, specifically a two mirror Ritchey-Chretién diamond-turned aluminum telescope. This system has two rotationally symmetric hyperbolic mirrors, a complication because of the added variable of a second focusing location. The goal is to provide a knowledge base to build metrology techniques for more complicated systems such as a three mirror anastigmatic optical system. The techniques applied include interferometers, profilometers, coordinate measuring machines and image evaluation. A laser interferometer was used in a dual-pass setup to measure optical surface form error and the assembled optical system performance and a white light interferometer was used to measure the surface finish. Linear and rotary profilometry were used to measure the form error of the optical surface and the fiducial surface errors. The secondary mirror showed form error as expected near ?/4 while the primary mirror had a large form error of over 3?. The optical component measurement showed a surface finish (4 nm RMS) that is expected for the 6061-T6 material. The system has 1.5 µm of wavefront error at its best focus point. The wavefront aberrations caused spot sizes that were 2x the magnitude predicted by Code V model and the MTF values were approximately 10-20% of the theoretical values.
Supporting Materials
The following faculty, students, and PEC affiliates are involved in this
project:
|
