Abstract: An interferometric testing system and method employing a multiple-aperture hologram. In an illustrative embodiment, the inventive optical testing system includes an interferometer which outputs a planar light beam and analyzes a reflected selected light beam. A multiple-aperture hologram generates N image points in an image plane of the optical system responsive to the planar light beam. A retro-reflector reflects a selected one of N light beams corresponding to the N image points transmitted by the optical system back through the optical system to generate the selected light beam. According to one aspect of the present invention, the multiple-aperture hologram includes N apertures generating the N image points and one of the N apertures overlaps at least one other of the N apertures. According to another aspect of the invention, the multiple-aperture hologram intersects a plane perpendicular to an axis defined by the centers of the interferometer and the retro-reflector.

Abstract: A method and apparatus for testing elliptical mirrors is provided which reduces the length of the test apparatus by half, provides for precise location of the focus of the interferometer beam, and precise measurement of the distance between foci of the elliptical mirror under test. A small reflective sphere (10) with an optical passageway (15) through its center is used to locate the focal point (f.sub.2) of the interferometer (5) within interferometric precision. A plane mirror (30) is placed half way between the focal points of the ellipse (20) under test with one of the elliptical foci coincident with the interferometer focal point (f.sub.2). The elliptical mirror (20) under test is placed with reflective concave surface facing away from the interferometer (5) to receive light reflected from the plane mirror (30). The optical passageway (15) is sized to emit a volume of light to fill the elliptical mirror surface (22) after reflection from the plane mirror (30).

Abstract: The present invention provides a lens holder (14) for a lens under test (26) in an in-line hologram interferometric test apparatus (10) which includes a flat reflective surface (34) for rotationally positioning the lens under test (26) and a parabolic reflective surface (32) for translationally positioning the lens under test (26). According to this configuration, the lens holder (14) is translationally positioned using the parabolic reflective surface (32) to reflect radiation to a focal point (24) along the hologram (22). The hologram (22) returns the radiation to the parabolic reflective surface (32) which reflects it back to the interferometer (12) at a precise distance and position using normal interferometric techniques. The lens under test (26) is rotationally positioned by pivoting the lens holder (14), both in tip and in tilt, so that the flat reflective surface (34) is nulled to the interferometer (12).

Abstract: The present invention provides a lens holder (14) for a lens under test (26) in an in-line hologram interferometric test apparatus (10) which includes a flat reflective surface (34) for rotationally positioning the lens under test and a spherical reflective surface (32) for translationally positioning the lens under test (26). According to this configuration, the lens holder (14) is translationally positioned using the spherical reflective surface (32) to reflect radiation back to the interferometer (12) at a precise distance and position using normal interferometric techniques. The lens under test (26) is rotationally positioned by pivoting the lens holder (14), both in tip and in tilt, so that the flat reflective surface (34) is nulled to the interferometer (12). Thereafter, the lens holder (14) is correctly positioned relative to the hologram (22) and interferometer (12) so that when the lens under test (26) is seated on the lens holder (14), its aspherical shape can be tested.

Abstract: The invention resides in a method of measuring position and angle comprising the steps of providing a tooling telescope, a transparent target surface and an alignment target having a light reflecting face confronting the telescope. The light reflecting face being defined by a recess having a parabolic surface and a flat surface surrounding the parabolic recess. The method further includes using light reflected off the flat surface to create collimated light passing through the target surface to define an angle of measurement of the tooling telescope and using light reflected off the parabolic surface to focus a point on the transparent target surface to measure position.

Abstract: A tooling apparatus and method for machining a blank having a first surface portion with a first spin center and a second surface portion with a second spin center offset from the first spin center. The improved tooling apparatus includes a turning fixture connectable to a rotatable spindle in one of a first position and a second position. The first spin center of the blank aligns with the axis of rotation of the spindle when the turning fixture is in its first position and the second spin center of the blank aligns with the axis of rotation when the turning fixture is in its second position. In the preferred embodiment, the rotatable spindle includes a dowel cooperative with first and second bores formed in the turning fixture to position the turning fixture relative to the spindle. The first and second bores are separated a distance equal to the distance between the first spin center and the second spin center of the blank.

Abstract: An optical assembly (10) includes a first plurality of optical elements (14) providing the viewer a first field of view and a second plurality of optical elements (18) that, when moved into the optical path (16), provides the viewer with a second field of view. A support structure (36) for the second plurality of optical elements (18) includes a permanent magnet (64) that is disposed to cause a switch (66) located on the housing (12) of the optical assembly (10) to close. The changing of the position of the switch (66) results in a signal being provided to identify to the viewer which field of view is being presented by the assembly (10).

Abstract: A reference reflector alignment aid (26) is provided including an alignment indicator (28). The alignment aid (26) is secured to a reference reflector (30) such that the alignment indicator (28) is located essentially at the optical center of curvature (32) of the reference reflector (30). The alignment aid (26) and reference reflector (30) are movable as a unit to position the optical center of curvature (32) coincident to the focal point (24) of an element or optical system to be tested (20).

Abstract: A thermal imaging device (10) provides for its use with a variety of accessory telescopic lenses (12). Each of the accessory telescopic lenses (12) and the thermal imaging device (10) include cooperating physical features allowing the lenses (12) to be mated with the device (10) in a single relative position. Each lens (12) also carries a uniquely positioned magnet (176), and the thermal imaging device (10) includes a plurality of magnetically-responsive sensors (178) responding to the magnets (176) of the various lenses (12) to identify which (if any) of the accessory lens (12) is installed on the device (10). Some of the accessory lenses (12) also include a variable-power feature. These variable-power lenses (12) have an additional magnet (182) moving between an effective position and an ineffective position in response to a user-selected power setting for the lens (12).

Abstract: A video camera (28) is provided including an image receiving surface (30). A monitor (36) is operably coupled to the video camera (28) to display an image (34) received at the image receiving surface (30). A reference reflector (24) is secured to the alignment camera (28) such that a reference portion (40) of the image receiving surface (30) is located at the optical center of curvature (32) of the reference reflector (24). An alignment mark (44) is coordinately positioned with the reference portion (40) on the monitor (36). The video camera (28) and the reference reflector (24) are movable as a unit to position the optical center of curvature (32) of the reference reflector (24) coincident with the focal point 22 of an element or optical system to be tested (18).

Abstract: An optical assembly (10) includes a first plurality of optical elements (14) providing the viewer a first field of view and a second plurality of optical elements (18) that, when moved into the optical path (16), provides the viewer with a second field of view. A support structure (36) for the second plurality of optical elements (18) includes a permanent magnet (64) that is disposed to cause a switch (66) located on the housing (12) of the optical assembly (10) to close. The changing of the position of the switch (66) results in a signal being provided to identify to the viewer which field of view is being presented by the assembly (10).

Abstract: A laser rangefinder (50) having visual, transmit and receive optical channels all arranged on a common rangefinder axis (70). A laser emitter (54) located on the axis directs its light away from the rangefinder output toward a reflector surface, also located on the axis. The reflector in turn reflects the laser light back toward the output to an objective lens (52) which collimates the reflected light into a collimated output beam. A portion of the light reflected from the target is passed through the objective lens and imaged onto a reticle (66) on the axis. A dichroic reflector (62) intercepts the imaged light and refracts a portion of the light to a field stop 60 and then to a detector 58, both located on the axis. A range display (64) is located in the plane of the reticle and off the axis for display target range information. An eye piece (68) receives light passing through the reticle.