An electro-optical sensor is described which provides a high resolution measurement of the location of the edge of an object. By passing the electrical pulse produced by an edge sensor into a multiply tapped delay line the location of the edge of an object can be measured with high resolution.

An electro-optical measuring system is described wherein a laser or light beam is precisely translated in a straight line perpendicular to the direction of propagation of the beam at a uniform, repeatable speed to define a time-varying sensing field whose energy is picked up by a photosensor which yields an output signal. An object whose dimension is to be measured is inserted in the field whereby the output signal of the photosensor takes the form of a pulse whose leading edge is developed by t...

A lens system which has a built-in reference surface and which provides an emerging wavefront of variable radius of curvature useful in a Fizeau interferometer or a differential autocollimator is described. By interposing between the reference surface and the test surface a collimating lens whose distance from the reference surface can be varied, an emerging wavefront is produced whose radius of curvature can be varied from some positive value to infinity to some negative value depending on the ...

An angular displacement interferometer system capable of measuring accurately changes in angular displacement comprises a source (10) of a frequency stabilized input beam with two linear orthogonally polarized components; a tilted parallel plate or shear place (16) with regions of reflection, antireflection, and polarizing coatings for converting the input beam (12) into two separated, parallel, orthogonally polarized beams (30, 31); a half-wave retardation plate (29) located in one of the separ...

In an interferometer alignment system comprising an interferometer having a plurality of movable elements (78) alignable with respect to an optical axis, a source of radiant energy (1) for the interferometer, means (9, 13) for providing a measurement wavefront (10 M) and a reference wavefront (10 R) from the radiant energy (1), and means (5, 14) for collecting the measurement and reference wavefronts and focusing them as spots (15 R, 15 M); the improvement comprising a camera (18) having a photo...

The high intensity illuminator of the invention includes a mounting fixture, a receiving surface spaced from the mounting fixture, and a plurality of semiconductor illumination sources which are implemented, most preferably, by light emitting diodes or laser diodes. Each illumination source is operable for emitting an outwardly-diverging illumination cone along an axis of illumination of the source at a predetermined illumination wavelength. The plural illumination sources are mounted on the mou...

A pair of orthogonally polarized optical beams that differ in frequency by a constant oscillator-generated reference frequency are directed through and traverse respective fixed and variable length paths of a heterodyne interferometer, following which the beams are mixed and directed to a detector that generates an electrical measurement signal having a phase that varies with changes in the variable path length. Changes in the measurement signal phase are determined by counting cycle-to-cycle ph...

The optical assembly of a GDI instrument is configured to deviate or steer stray beams away from the pupil of the instrument's imaging device and/or to suppress stray beams. Stray beam deviation is optimized by selecting particular wedge and/or tilt configurations that achieve the desired stray beam deviation while avoiding or at least minimizing phase offset at the optimum metrology plane. Stray beam suppression can be achieved by providing the diffractive groove profile of the instrument's opt...

Low coherence illumination is used in interferometric methods and systems which exhibit improved precision and flexibility. According to a first aspect of the invention, both a phase shifting interferometry (PSI) analysis and a scanning white light interferometry (SWLI) analysis are applied to a single 3D interferogram. This allows the precision of PSI to be achieved without being limited by the 2.pi. phase ambiguity constraint. According to another aspect of the invention, a position of a contr...

Apparatus is disclosed for the generation and display of interference patterns for the purpose of quantifying the distortion of either a surface or a transmitted wavefront. The invention comprises, in one embodiment, means to align the elements comprising the interferometer cavity, means to continuously magnify, i.e., zoom, the aperture diameter of the interference pattern, means to focus either the measured or limiting aperture onto the face of the vidicon, and means for transducing both the al...