Abstract: Holograms of objects are made on a light-responsive medium with the aid of a reference beam and an object beam reflected by the object and, throughout the light-responsive medium, are rendered insensitive to object size by projecting the reflected object beam onto the medium at an angle to said reference beam which is constant throughout the medium within a tolerance imperceptible to that light-responsive medium in terms of spatial frequency of the hologram. Preferably, the reflected object beam is projected onto the light-responsive medium at a constant angle of incidence throughout that medium, and is projected through an aperture having a diameter equal to the angle of the reflected object beam to the reference beam, divided by the product of an angular resolution of the hologram and the above mentioned spatial frequency.

Abstract: Methods and apparatus for passing laser light into an optical fiber having a light input face thereacross, focus the laser light onto a front focus plane of focusing means for forming a spatial spectrum of light distribution in which noise frequencies are spatially distributed about a central spot of light. The position of the light input face of the fiber is coarsely adjusted relative to the focus plane for capturing with the fiber the central spot of light to the exclusion of distributed noise frequencies. The central spot of light is finely adjusted in position on the light input face of the fiber by tilting the focusing means and the light input face of the fiber until a maximum of light energy from the central spot is transmitted through the input face and the fiber. The latter tilting preferably is effected relative to a rear focal plane of the focusing means or about a pivot in such rear focal plane.

Abstract: Laser apparatus having a pair of concave end mirrors facing each other through a laser gain medium. The end mirrors are mounted so as to permit tilting thereof. One of the end mirrors has a center of curvature situated between the end mirrors at a distance from the other end mirror of up to one-eighth of the distance between the end mirrors through the laser gain medium. The other end mirror has a center of curvature situated between the end mirrors at a distance from each of the end mirrors of at least three-eighth of the distance between the end mirrors through the laser gain medium. In practice, this substantially reduces the sensitivity of the laser apparatus and laser action to end mirror tilting and to bending of the laser gain medium or of a tube containing same. It also substantially increases the alignment tolerance and adjustability of the end mirrors and other parts of the laser structure and permits potting of gas lasers.

Abstract: An odograph in which calibrated portions of heading and distance signals are used for displaying locations. A magnetic compass is provided including a North-seeking spherical surface carrying a reflective segment, the position of which is sensed by electro-optical components which derive and generate an appropriate heading signal. An odometer generates distance signals which are integrated with the heading signals, calibrated by gating with a probabilistic function. A visual display is driven by means which are responsive to coincidence of the odometer and heading signals but which exclude response to coincidence of an odometor signal and two heading signals.