Abstract: A method and an instrument are provided for checking and adjusting the accuracy of an alignment device which transmits a collimated (e.g. laser) light beam that serves as an alignment reference. That beam generator defines a precise reference for purposes of alignment of various other forms of apparatus, often over great distance. The checking and adjusting instrument (which is totally passive) provided by this invention is precisely attached to the alignment device, temporarily, and receives the reference beam of light from the device. The instrument displays an indication of misalignment of the beam, and also aids in correcting same.

Abstract: Correction is provided for a curved or skewed scan output from a penta assembly in an instrument that scans a beam in a predetermined fashion. The penta assembly has first and second beam directing surfaces supported at a predetermined angle to each other. A laser beam source directs a beam along a path preferably coinciding with the scanning axis of said mount toward the first surface, and a first optical element converges the input beam to a spot on that first surface. Then the reflection or redirection of such spot is transmitted onto the second surface, and finally the redirected beam from that second surface is transformed into a collimated output beam from the penta assembly. This is accomplished using simple passive optical elements, e.g. convex lenses or optical equivalents, which are readily incorporated into the penta assembly.

Abstract: Correction is provided for a curved or skewed scan output from a penta assembly in an instrument that scans a beam in a predetermined fashion. The penta assembly has first and second beam directing surfaces supported at a predetermined angle to each other. A laser beam source directs a beam along a path preferably coinciding with the scanning axis of said mount toward the first surface, and a first optical element converges the input beam to a spot on that first surface. Then the reflection or redirection of such spot is transmitted onto the second surface, and finally the redirected beam from that second surface is transformed into a collimated output beam from the penta assembly. This is accomplished using simple passive optical elements, e.g. convex lenses or optical equivalents, which are readily incorporated into the penta assembly.

Abstract: Opposite wedge plates having identical non-parallel surfaces are joined to provide an optical element which will receive a portion (e.g. one-half) of an input light beam, and project the side-by-side interference patterns directly onto a viewing screen to check for collimation of the beam. The instrument incorporates a rectangular housing having an input window in one side of the housing for admission of the beam being investigated, and a viewing window in another side located at right angles to the input window. A viewing screen is fitted into or supported in the viewing window. The optical element comprises a matched pair of optical wedge plates having the same wedge angle and being supported side-by-side with their wedge directions opposite, and is supported in and across the housing extending at forty-five degrees to the input window, from a corner adjacent the viewing window to an opposite corner.

Abstract: A passive target device has as its principal element an optical axcicon having an optical axis which is intended to be aligned with a reference beam. The axicon has a geometric center line coincident with its optical axis and includes at least one facet which will form a reference image when the optical axis is aligned with the reference beam, such image being symmetrical in a plane perpendicular to the optical axis. This optical axicon is mounted in a holder, such as a tubular body, having an inlet window and a output or display window, and is adapted to be supported a distance away from the source of the beam, which may vary from less than one meter up to several hundred meters. Different forms of optical elements may be utilized with the axicon, the elements employing one or more like facets arranged symmetrically about the optical axis.

Abstract: Opposite wedge plates having identical non-parallel surfaces are joined to provide an optical element which will receive a portion (e.g. one-half) of an collimated input light beam, and project the side-by-side interference patterns directly onto a viewing screen to check for collimation of the beam. The instrument incorporates a rectangular, preferably cube shaped, housing having an input window in one side of the housing for admission of the beam being investigated, and a viewing window in another side located at right angles to the input window. A viewing screen (such as a diffusing plate) is fitted into or supported in the viewing window. The optical element is supported in and across the housing extending at forty-five degrees to the input window, from a corner adjacent the viewing window to an opposite corner. The optical element comprises a matched pair of optical wedge plates having the same wedge angle and being supported side-by-side with their wedge directions opposite.

Abstract: The target structure of this invention is comprised of a thin optically transparent lightguide sheet, preferably two sheets bonded together with flat sides. The thin sheet material is chosen to make a good pocket-size lightguide and provide an adequate tradeoff to cost, manufacturing ease, and internal reflective loss, and may be colored to provide an optical filter enhancing contrast of the viewed image by rejecting unwanted light. At the entrance edge of the target are side-by-side formations generating optically the lens and axicon function, and separately the reference lens function. The exit edges of the sheets are either flat and perpendicular to the faces, or at such an angle as to direct images at a prescribed angle with respect to the face of the sheet(s). The entrance edge of the one sheet is formed with a curve to produce the optical lens and axicon functions, the shape of which can be chosen to enhance any difference occuring between the images when the incoming beam is not on center.

Abstract: Targets for use with scanning light beam leveling/marking devices, are constructed with their elements assembled as unitary target structure. The lens and beam divider functions are provided by optical quality fresnel lenses attached to or formed on a polycarbonate block, these parts thus can be made essentially an integral element. These special fresnel lens which are optically equivalent of the input lens and beam dividing axicon, and the viewing screen diffuser function provided by a frosted viewing plate. A separate fresnel lens is mounted alongside the beam dividing lenses and functions to provide a reference image on the viewing screen. The optical path for the impinging light beam (after it is divided) may be transmitted directly through the body block, from the input to the view window, or through a reflector surface at a side of the block, the block body of the target functioning as a waveguide.

Abstract: The invention provides a passive hand held target for use with a scanning light beam, particularly a laser beam, in which the beam impinged upon (i.e. input to) the target is divided and the resultant beams are directed to a viewing screen witha diffusing function, where an observer can discern equality or inequalities of their images as the target is moved to center its input window with respect to the scanning beam. Adjustment of the target then provides a reference for marking of a surface adjacent the target. The beam divider may include a mask which produces a pair of symmetrical easy to compare beam shapes. An alternative beam divider is an axicon. Holograms can be used as equivalent optical devices for the lens and axicon beam dividing function and for the diffusing viewing function, as well as to direct the beams at convenient angles.