Subaperture stitching interferometry for testing mild aspheres

Paul Murphy; Jon Fleig; Greg Forbes; Dragisha Miladinovic; Gary DeVries; Stephen O'Donohue

doi:10.1117/12.680473

14 August 2006 Subaperture stitching interferometry for testing mild aspheres

Paul Murphy, Jon Fleig, Greg Forbes, Dragisha Miladinovic, Gary DeVries, Stephen O'Donohue

Proceedings Volume 6293, Interferometry XIII: Applications; 62930J (2006) https://doi.org/10.1117/12.680473
Event: SPIE Optics + Photonics, 2006, San Diego, California, United States

Abstract

Interferometric tests of aspheres have traditionally relied on so-called "null correctors". These usually require significant time and expense to design and fabricate, and are specific to a particular asphere prescription. What's more, they are tedious to align and calibrate. Aspheres can also be tested without null correction (using a spherical wavefront), but such capability is extremely limited. A typical interferometer can acquire only a few micrometers of fourth-order aspheric departure due to high-density interference fringes. Furthermore, standard software packages do not compensate for the impact upon a non-null measurement of (i) the part's aspheric shape or (ii) the interferometer's optical aberrations. While fringe density and asphere compensation severely limit the practical utility of a non-null asphere measurement, subaperture stitching can directly address these issues. In 2004, QED Technologies introduced the Subaperture Stitching Interferometer (SSI^(R)) to automatically stitch spherical surfaces (including hemispheres). The system also boosts accuracy with in-line calibration of systematic errors. We have recently added aspheric capability, extending non-null aspheric test capability by an order of magnitude or more. As demonstrated in the past on annular zones of nearly nulled data, subaperture stitching can extend the testable aspheric departure. We present a more generally applicable and robust method of stitching non-null aspheric phase measurements. By exploiting novel compensation schemes and in-line system error calibration, our subaperture stitching system can provide significantly better accuracy and increased testable aspheric departure over an unstitched non-null test. Examples of stitched non-null tests are analyzed in this paper, and cross-tested against corresponding null tests.

Citation Download Citation

Paul Murphy, Jon Fleig, Greg Forbes, Dragisha Miladinovic, Gary DeVries, and Stephen O'Donohue "Subaperture stitching interferometry for testing mild aspheres", Proc. SPIE 6293, Interferometry XIII: Applications, 62930J (14 August 2006); https://doi.org/10.1117/12.680473

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