Abstract: An apparatus for continuous measurements of the density of variegated liquids, utilizing the angular displacement of the limiting angle at total reflection. Among other purposes the apparatus is useful for measurements of the acid concentration of liquids, such as in a storage battery in a motor vehicle to determine the state of charge of the battery. The apparatus comprises a light rod, in which the end to be immersed in the liquid is provided with a measuring surface and preferably also with a deflecting surface, a light source emitting a bundle of rays into the rod toward the measuring surface at a given divergent angle and a light-sensitive element positioned in the path of rays.

Abstract: A wide angle lens of high performance comprising twelve lenses grouped in ten components which satisfies the following four conditions:F/1.8 <.vertline. F.sub. 1.2.3.4.vertline.< F/1.1, F.sub.1.2.3.4. < 0 (1)F/0.6 <.vertline. F.sub.1.2.3.4.5.6 .vertline.< F/0.15, F.sub.1.2.3.4.5.6 < 0 (2i)F/1.4 <F.sub.1.2.3.4.5.6.7 < F/0.8 (2ii)0.1 < n.sub.8 - n.sub.9 <0.2 (3)0.3.sub.l < (d.sub.1 + d.sub.2 + d.sub.3 + d.sub.4 + d.sub.5) < 0.

Abstract: A method and apparatus for nondestructive testing of articles by holography in which light beams from a virtual point source of laser light and from an observation point are reflected by a reflector toward the same point on the object being checked. The light beams when extended beyond the reflector intersect on an ellipsoid having the point source and the observation point as foci. A plate having a hologram of the article is interposed between the observation point and the reflector and flaws in the object being tested show up on the plate as interference lines when the object is modified in shape by a mass influence such as a temperature change, or a change in pressure thereon, or by vibrations.

Abstract: A method is disclosed for measuring in-plane deformation in a surface of an article, which includes attaching to the surface a grid pattern which is periodic in relief, allowing the grid pattern to become deformed and thereafter taking a cast replica of the deformed grid pattern and processing the replica under laboratory conditions to produce Moire fringes from which the deformation can be measured. The cast replica is taken by loading a rigid carrier in the form of a glass plate with a layer of silicone rubber which is a curable shape-retentive material, impressing the silicone rubber layer upon the deformed relief grid pattern and curing the silicone rubber so that the replica is a faithful and permanent reproduction of the deformed pattern.

Abstract: In an optical system the use of a plurality of air lenses set in an optical medium of higher refractive index than air at a predetermined distance from an object such that various optical aberrations are minimized or eliminated by using aplanatic optical surfaces. Refraction occurs only for a ray going from the higher to the lower refractive index medium. Rays entering the higher refractive index medium from the lower are never refracted since the optical surface is always chosen to have its center or radius coincident with the object or image being optically operated on by the lens. The system can be used to magnify the image of an object, the object being most any two-dimensional representation such as a negative or a positive print. The object might alternatively be a light source or an external object whose rays are imaged onto an embedded light sensor so that the functions of the source or sensor respectively can be enhanced by the optical system.

Abstract: Submicron-sized particles are detected by a system which observes emission, as by scattering or by fluorescence from particles undergoing Brownian motion in a region of a fluid medium excited by an evanescent wave created adjacent an interface between the fluid medium and a multiple internal totally reflecting cell or light guide. The excited region can range in depth between several wavelengths and a fraction of the wavelength of the exciting beam, hence serves as an "aperture" having a dimension of about the same order of magnitude as the particles being detected. The particles can be classified according to size by examining the amplitude modulation arising out of the motion of the particles through the aperture.

Abstract: A three element 12X eyepiece has an apparent field of view of about 51.3.degree. and a maximum exit pupil diameter of substantially 1.25mm.

Abstract: A four element microscope objective has a predetermined magnification and a numerical aperture of substantially 0.10. The microscope objective provides correction for the usual chromatic aberrations as well as spherical aberrations, coma, astigmatism and a substantially flat image field over a 24mm field when used with a telescope objective as described in U.S. Pat. No. 3,355,234 and a typical 10.times. eyepiece.

Abstract: The accuracy with which the distance between the end faces of a length type of gaging standard can be measured by a laser interferometer is improved by mounting the gaging probe at one end of a slide in fixed coaxial alignment with a laser beam target secured to the opposite end thereof. The slide is, in turn, mounted on a slidable carrier to form a V-notch of changeable width containing a steel ball whose weight imparts a predetermined thrust to the gaging probe unaffected by the force required to move the carrier so as to bring the probe into gaging contact with a fixed surface. A planar surface is adjustably swiveled into cohesive coincidence with one end face of the length standard to duplicate the orientation thereof relative to the gaging table which supports the length standard.

Abstract: A wide angle photograhic lens which has the back focal distance of 1.2 to 1.

Abstract: A varifocal lens system comprising a pair of movable lens groups located outwardly which are symmetrical with respect to the diaphragm and a pair of stationary lens groups located inwardly from said groups which are also symmetrical with respect to the diaphragm, said movable lens group being moved axially in the symmetrically spaced relationship with respect to the diaphragm and simultaneously the entire lens system being displaced as a unit by an axial distance depending on the amount of displacement of the movable lens group to satisfy the correct image-forming conditions throughout the entire magnification range while maintaining an object plane and an image plane spaced at a fixed axial distance.

Abstract: A two-element lens which provides an emerging beam of a height H from the optical axis where H is proportional to the product of the focal length of the lens and an angle made by an incident beam emanating from the focal point of the lens on the optical axis thereof.

Abstract: A retro-focus type wide angle lens system comprises a negative first component located on the object side and including at least one negative meniscus lens; a positive intermediate second component consisting of one or two lens groups including at least one biconvex lens group and a rear third component which includes of four consecutive lenses including, in order, a positive meniscus first lens having a rear convex surface, a biconcave second lens, a positive meniscus third lens having a rear convex surface and a fourth positive lens; whereby the back focus of the total lens system is longer than the focal length, and satisfying the following conditions:(1)d.sub.c0 > d.sub.c2(2).vertline.r.sub.c2 .vertline..gtoreq. .vertline. r.sub.c3 .vertline.(3)V.sub.c1 > V.sub.c2(4)d.sub.c0 > d.sub.c4whereinr.sub.c2 and r.sub.

Abstract: A retrofocus-type wide-angle photographic lens system having a predetermined airspace in said lens system and arranged to be focused for close-up photographing and to prevent aggravation of aberrations by moving a front lens group positioned on the object side of said airspace toward a rear lens group positioned on the image side of said airspace at the same time as advancing the lens system as a whole.

Abstract: A zoom projection lens having six elements with a second biconcave negative element being movable for zooming. Five of the six elements are made of plastic materials and the use of aspheres on two surfaces, including one surface of the movable element, is disclosed to achieve good optical performance at a relative aperture of at least f/1.57.

Abstract: An interferometer having two spaced apart but parallel composite beams passing through respective fluid containing cells with the radiation output of these cells being imaged onto a detector. The optics at one end of the cells are made movable with respect to the optics at the other end of the cells in order to accommodate various size cells and materials, and to simplify optical alignment of the interferometer without disturbing the focusing properties of the instrument.

Abstract: Louvered echelon lenses are provided that comprise an optically clear layer having at least one of its large-area surfaces configured as a set of echelon lens elements, and physically attached in optical connection with said layer, an internally louvered layer that comprises an optically clear polymeric matrix and a set of thin optically limiting louvers supported within the matrix in a spaced side-by-side relation.

Abstract: A lens system for a camera comprises a pair of axially shiftable components for varying the focal length, coupled with a cylindrical zoom-control member, and a further axially shiftable component for changing the object distance, coupled with a cylindrical focusing-control member. An operating tube coaxial with the two control members engages the zoom-control member for rotating same, the focusing-control member being releasably entrainable by the zoom-control member between a limiting macro-range position and a close-up position through a deactivable coupling which may include two coacting lugs on these members or a pawl on the zoom-control member retractable by an axial shift of the operating tube. A toothed detent ring, nonrotatable but axially slidable, is also movable by that tube into engagement with the focusing-control member for arresting same against the force of a biasing spring urging that member into its limiting macro-range position.

Abstract: Distance measurement by conventional optical interferometry requires physical movement of an optical element. The present system obtains interference with a continuous range of radiation wavelengths, providing a direct measurement of a constant optical path difference, in terms of the fringe count and the end wavelengths of the range employed. Variations in the optical path difference occurring during the measurement are compensated by simultaneous interferometry with a fixed wavelength.

Abstract: An objective system for motion picture cameras wherein a zoom lens is installed in a barrel and the barrel is surrounded by two ring-shaped selectors. The rear selector is rotatable to change the focal length of the lens by moving the optical elements of the rear group of optical elements of the lens with and relative to each other in the direction of the optical axis. The front selector is rotatable within a first angle to focus the image of a subject which is located at a distance of 5 ft. or more from the barrel, and within a second angle to focus the image of a subject prior to the making of close-up shots. The front selector moves the optical elements of the front group of optical elements of the lens during rotation within the first angle and the optical elements of the second group during rotation within the second angle. The focussing for close-up shots can be made after the focal length of the lens is reduced to a minimum value.