<title>Phase-shifting via wavelength tuning in very large aperture interferometers</title>

Abstract

We describe a high performance interferometer system which provides measurements of extremely large parts in production with a high throughput. The system has a clear aperture of 610 mm. Mechanical stability is addressed by phase shifting via wavelength tuning, which allows locking the interferometric cavity for increased stiffness. We describe in detail the special illumination and optical mounting systems and their impact on the optical configuration, phase shifting and detection systems and present results on large optical flats in both transmission and reflection.