Abstract: A wide angle telecentric projection lens system, having a long back focal distance, includes a front lens doublet, comprising negative and positive meniscus lens elements, located in front of an aperture stop, and a rear lens group on the other side of the aperture stop, the rear group comprising a rear lens doublet which includes positive and negative meniscus lens elements, the rear doublet having its curvature reversed relative to the front doublet but having an air space between its component lens elements, plus two biconvex lens elements slightly spaced from each other and from the second doublet. A beam splitting optical prism and/or similar optical element(s) may be included between the rear lens group and the object.

Abstract: A zoom lens system comprises, in order from the object side, a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group and a positive fifth lens group. The first lens group includes a positive lens component comprising a negative and a positive lens cemented together, and a positive meniscus lens component convex to the object side. The second lens group includes a negative lens component and a negative lens component comprising a negative lens and at least one positive lens cemented together. The third lens group includes at least one positive lens component and a positive lens component comprising a positive and a negative lens cemented together. The fourth lens group includes a negative lens component. The fifth lens group comprises a forward and a rearward group spaced apart a substantial distance from each other by an air space.

Abstract: In a wide angle zoom lens system comprising a diverging lens group and a converging lens group which are both movable on the optical axis of the lens system to vary the air space between the two groups so that the magnification of the image is variable while the image plane is being maintained at a fixed position, the diverging lens group comprises, in order from the object side, a negative meniscus lens component convex to the object side, a positive lens component, a negative lens component, a positive meniscus lens component convex to the object side, the four lens components being separate from one another, and an air chamber having a converging effect being formed between the second and the third lens component, the third and the fourth lens component being so disposed that the air space therebetween is greater than the center thickness of the third member, and the converging lens group comprises at least four positive lens components a positive lens component out of which is closest to the object side a

Abstract: In an interferometric measuring system, a collimated monochromatic and coherent beam of light (1, I.sub.1 -I.sub.n)impinges on a grating 1 disposed parallel to the test surface 2. It has been found that in the above arrangement, a diffraction order (preferably the first diffraction order S.sub.1 -S.sub.4) of the light reflected from the face of the grating opposite to the test surface is always parallel to three diffraction orders of the radiation which after being first diffracted upon its first passage through the grating and reflected from the test surface is again diffracted upon its second passage through the grating. These four radiations (S.sub.1 to S.sub.4) generate two interference fields, the combination of which generates a beat pattern.According to the invention, the angle of incidence of the radiation impinging onto the face of the grating opposite to the test surface is chosen in such a way (preferably from 0.5.degree. to 5.degree.

Abstract: The present invention is an improved multiple ratio single particle counter. Intensities of scattered radiation are measured at more than two angles and ratios of these intensities are derived. These ratios are compared with calibration curves to determine an unambiguous measure of the particle parameter.

Abstract: A wide-angle photographic objective comprises, in the order from the object side, a positive meniscus lens convex to the object side, a negative meniscus lens convex to the object side, a negative meniscus lens convex to the object side, a positive lens, a negative meniscus lens convex to the object side, a positive lens, a meniscus lens convex to the image side and comprising a biconcave lens and a biconvex lens cemented together, a meniscus lens convex to the image side and comprising a biconcave lens and a biconvex lens cemented together, and a positive lens.

Abstract: An improved Gauss type lens system having a relatively large aperture ratio is provided. The lens system comprises seven components between object and image as follows; a first positive meniscus lens element, a second positive meniscus lens element, a third negative meniscus lens element, a fourth meniscus shaped doublet, a fifth positive meniscus lens element, and a sixth positive lens element. The entire lens system is capable of providing a relative aperture of F No. 1.2, an angle of view of 50.degree. and a back focus at least 0.7 times the overall focal length of the lens system.

Abstract: A unitary light source is imaged through a prism array to generate a plurality of preferably four apparent light sources forming a point of origin for a discrete lens sampling light path. From each apparent light source, each discrete sampling path diverges to a relay lens system. This relay lens system relays and registers to a lens sampling interval discrete images of each apparent light source. The images may be registered to a correspondingly apertured lens sampling diaphragm against which suspect optics are placed for measurement. A moving boundary locus sweeps the light between each apparent source and the sampling interval with paired boundaries of differing slopes which produce non-ambiguous points of intersection with respect to time. After passage through the suspect optics at the sampling interval, light is passed to a photodetector having an overlying set of apertures, each aperture corresponding to one of the four apparent light sources.

Abstract: The effect of angular errors or mismatching indices of refraction of color-compensation prisms of Abbe refractometers can be virtually eliminated by decentration of the lens used to image light on the refractometer reticle.

Abstract: An automated readout for a lens meter is disclosed in combination with a light beam deflecting type of lens meter such as that of a Hartman test. In such a light beam deflecting type of lens meter, a light source having one or more beams is passed through a suspect optical system and deflected by the suspect optical system to a deviated path. Measurement of the deviated path within a preselected area of excursion is typically equated to various powers of the suspect optical system in sphere, cylinder, cylinder axis, and prism. The invention provides for a means of measurement of deviated paths and includes a moving boundary locus with edges of distinctly different shape placed to intercept and occult said deflected beam in a known plane within the area of excursion at a distance from the suspect optical system. The moving boundary locus is typically arranged for movement along a predetermined path at a velocity within the known plane.

Abstract: This invention concerns a minus prescription hydrogel contact lens that permits oxygen diffusion to the cornea in sufficient quantity to avoid the effects of oxygen deprivation; avoids the physiological complications arising from damage to the bulbar conjunctivia due to compression of the limbal capillaries; and avoids corneal scleral or wetting deficiencies. These advantages are accomplished through a combination of lens design and hydrogel properties.

Abstract: An interferometer which is compensated for the effects of low frequency vibrations in the measuring arm. The resultant changes in optical path length are detected and control signals are applied to an electro-optical device adapted to change the phase of the light in the reference arm of the interferometer relative to that in the measuring arm of the interferometer so as to compensate for the changes of optical path length in the measuring arm of the interferometer.

Abstract: The invention contemplates a circular spectacle-lens blank which is optically finished on both its front and back surfaces and which is characterized by locally hardened registering central areas of both surfaces. The hardened areas are sized to be universally included within the spectacle-frame profile of all frames within a given variety of frames, and the outer annular areas are unhardened and of such effective radial extent as to embrace all of such profiles within said variety, so that each finished and hardened blank is adapted for later edging to the profile of a later selected one of the frames within the given variety. Various methods are described for creating the indicated locally hardened regions on the otherwise-finished lens blanks.

Abstract: An objective lens particularly for use in a low light level or night vision system designed to introduce a controlled amount of barrel distortion at the edges of its field of view to permit use with a flat input faced imaging tube.

Abstract: In an optical system, primarily adapted for use in light scattering diagnostics e.g. Raman, Rayleigh, laser fluorescence, an obscuration means is placed between the sample volume (or object) and a light collecting means (such as a lens or mirror) to limit the backscattered light collection passed through an aperture to a shorter length along the optical axis, thereby increasing the spatial resolution of the system. In general, the effective obscuring diameter is determined as twice the ratio of the square of the distance between the image of the aperture within the sample volume and the collection means to the distance between the collection means and the aperture, times the ratio of the aperture diameter to the desired length of sample volume. In refractive embodiments, obscuration is provided by an opaque disc adjacent a collection lens. In a second embodiment, obscuration is provided by a coaxial arrangement of independent fiber optical light pipes.

Abstract: The diameter of an optical fiber is continuously measured by directing a laser beam at the fiber to form a light intensity fringe pattern. The pattern is converted to a substantially sinusoidal electrical signal having a period proportional to the fiber diameter. The sinusoidal signal is forwarded to a tapped delay line to form a plurality of delayed replicas thereof having a predetermined delay therebetween. A pulse is generated for each zero crossing of all the sinusoidal signals and the pulses interleaved to form an output train having an interpulse interval proportional to a fraction of the fiber diameter.

Abstract: A wide angle lens system of an inverted telephoto type is provided. The lens system comprises six separate lens groups comprising, consecutively from the object to the image side a negative meniscus lens element; a positive doublet; a positive meniscus lens element; a biconcave single lens element; a positive lens element and a rear positive lens element. One of the lens elements of the fifth and sixth groups is a single lens element while the other is a doublet. The lens is capable of providing an aperture ratio greater than F/2.0, a field angle of approximately 64 degrees and a back focal distance greater than the focal length of the system.

Abstract: A system for measuring the lateral displacement between edges located on two spaced apart objects, with a precision in the order of 1 microinch, generates and analyses the diffraction pattern produced by the physical edge on one object and the aerial image of the edge on the other object. The system can be used for the alignment of the objects or the comparison of patterns located on the objects.

Abstract: Hologram apparatus for testing for defects in welds has a frame with means for supporting the frame. A laser beam is directed towards one end of the frame where it is reflected by a rotatable mirror onto an area of the weld lying in a predetermined direction within an arc of about 90.degree. extending from a point directly below the mirror. A head is mounted for rotation on said one end of the frame coaxially with the mirror. A photosensitive recording medium is mounted on the head for receiving laser light reflected from said weld. A reference beam mirror is mounted on the head for reflecting laser light from the rotatable mirror to the recording medium as a reference beam. The rotatable mirror and the head are interconnected to cause the ratio of the angular movement of the head to the angular movement of the rotatable mirror to be two to one.

Abstract: Index of refraction measurements are made by means of an optical device in which a coherent light beam is divided into an object beam and a reference beam, each of which is directed through a separate path in a common light transmitting medium. The object beam is also transmitted en route through a test volume that accommodates a substance to be tested. It is subsequently recombined with the reference beam to form a single output beam. The output beam is received by a photo detector and its intensity is measured. The intensity of the detected output beam is related to any phase shift between the object and reference beams. The phase shift in turn is a measure of the index of refraction of the test substance. Information relating to density, temperature and pressure of the test substance can be derived from measured index of refraction values by using conventional conversion formulas.