Browse Prior Art Database

Long Working Distance Interferometer

IP.com Disclosure Number: IPCOM000087320D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 39K

Publishing Venue

IBM

Related People

Bloem, HH: AUTHOR [+2]

Abstract

This interferometer measures small dimensions of objects which are not readily accessible to a measuring instrument.

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Long Working Distance Interferometer

This interferometer measures small dimensions of objects which are not readily accessible to a measuring instrument.

In one application, interferometer 10 is used to measure the minute deformations of an operative deformable target T in a deformographic storage display tube (DSDT). More particularly, the target T, which is sealed in the tube's envelope E, is located a finite distance D from the tube's window, i.e., faceplate
F. An electrostatic charge pattern placed by the tube's scanning electron beam EB on the target's remote side causes the associated target's deformable polymer layer (not shown) on the target's other side to deform (for example, see
U. S. Patent 3,676,588).

The light beam of the spectral lamp 11 of the light source of interferometer 10 has a predetermined fixed bandwidth. Preferably, lamp 11 is a mercury lamp which provides an intense light beam in the green spectral band, e.g., 5460 angstroms. The light beam is passed through interference filter 12, which excludes the longer and shorter wavelengths and, thus, provides a substantially monochromatic light beam of the desired wavelength, e.g., 5460 angstroms. The monochromatic beam in turn passes through a small aperture, e.g., one mm., of aperture member 13 and is condensed by condenser lens 14. Beam splitter 15 divides the beam into the sample and reference channels 16 and 17, respectively, of interferometer 10. Lens 14 images the aperture of member 13 at the diaphragm plane of the sample and reference objective lenses 16' and 17', respectively. Lenses 16' and 17' are matched and mounted symmetrically for a fixed magnification. For example, lenses 16' and 17' have a 55 mm. focal length and are set for 5...