Subaperture Testing For Mid-Frequency Figure Control On Large Aspheric Mirrors

A. F. Slomba; L. Montagnino

doi:10.1117/12.936347

15 November 1983 Subaperture Testing For Mid-Frequency Figure Control On Large Aspheric Mirrors

A. F. Slomba, L. Montagnino

Proceedings Volume 0429, Precision Surface Metrology; (1983) https://doi.org/10.1117/12.936347
Event: 27th Annual Technical Symposium, 1983, San Diego, United States

Abstract

Encircled energy is an important specifying parameter for large, high quality optical telescopes and is critically dependent on the spatial frequency distribution of surface errors. Errors of surprisingly small amplitude whose spatial frequencies lie between those of the classical pupil aberrations and defects associated with the microroughness regime (i.e., whose periods lie below a millimeter) have a profound effect on encircled energy performance. This is particularly true at short wavelengths. Occurrence of this type of defect (called mid-frequency error) becomes more likely with increased mirror size. Full aperture interferograms that provide wavefront information over the pupil can lead to grossly inadequate performance predictions. Accurate prediction and the desired level of performance can only be achieved by precise measurement and control of the mid-frequency errors. This paper describes the processes and instrumentation for measuring and controlling figure error in this critical frequency domain during the manufacture of a high quality large aspheric mirror. Measurements of surface defects at the 0.002 µm rms level in the spatial frequency range of 0.01 to 0.25 cycle per millimeter are illustrated. The design and certification of a subaperture interferometer system is described.

Citation Download Citation

A. F. Slomba and L. Montagnino "Subaperture Testing For Mid-Frequency Figure Control On Large Aspheric Mirrors", Proc. SPIE 0429, Precision Surface Metrology, (15 November 1983); https://doi.org/10.1117/12.936347

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available