Charles R. Hayslett

Rough surface interferometry at 10.6 μm

An IR Twyman-Green interferometer is described. It uses a cw CO(2) laser as a light source operating at a 10.6-microm wavelength. Theoretical analysis and experimental measurements of the relationship between the contrast of the interference fringes and the rms roughness of test surfaces are discussed. Interferometric testing results and special alignment methods are shown for rough surface optics.

Wave front derivation from interferograms by three computer programs

A comparison of the results of three different computer programs for the reduction of interferograms is presented. These programs use either global or local surface fitting or a combination of both and were developed at White Sands Missile Range. The global fitting algorithm uses Zernike polynomials while the local surface fitting algorithm interpolates a quadratic surface considering only nearby data points.

10.6 Micrometer Interferometric Testing Of Infrared Optical Components And Aspherics

Infrared interferometric systems using a CO2 laser operating at a wavelength of 10.6 μm are described. Specific systems discussed are a Twyman-Green interferometer and a Twyman-Green interferometer with an infrared computer-generated hologram (IRCGH). The reduced sensitivity due to the longer wavelength enables us to test optical components necessary for IP high-energy laser systems. This paper also illustrates typical results obtained from testing infrared trans litting materials, diamond-turned metal mirrors, and aspherics. Special alignment techniques and basic limitations of infrared interferometry are discussed.

Long-Wavelength Interferometer In The Optical Shop

The in situ testing of an unpolished off-axis parabolic mirror with a vertex radius of 12.8 m, a diameter of 1.42 m, and an off-set of 1 m is described. Interferograms are shown that were obtained during the fabrication process by means of a lona-wavelength interferometer that uses a CW CO2 laser operating at a wavelength of 10.6 µm as the coherent light source.

Testing The White Sands Missile Range (WSMR) 100 mm Focal Length Rotating Prism Camera Lens

A quick review of the imaging problems encountered with rotating prism camera systems will be presented. The system performance of a diffraction limited objective when added to a rotating prism camera will be shown. The design considerations of a photographic objective designed specifically for use with rotating prisms will be briefly discussed. The methods of testing a lens and the rotating prism will be presented. Interference tests wilt be shown for a new rotating prism camera lens as will similar tests on a standard photographic objective when used on the rotating prism camera.

Multi-Wavelength Interferometric Testing

We have built a modified Twyman-Green interferometer illuminated with a krypton laser. The configuration allows for center of curvature or autocollimation testing at various selected wavelengths. Software data reduction uses a Zernike polynomial fit to the wavefront. The interferograms are all made without moving the source, so the effects of axial color, lateral color, and chromatic variation of aberrations will exhibit themselves in a straightforward fashion in terms of the coefficients of the Zernike polynomials. Also, a scheme for using this information in the calculation of a polychromatic optical transfer function (OTF) has been developed. Requirements for the interferometers optics are examined, and interferometer calibration discussed.