Abstract: A wide-angle zoom lens system comprising a front negative lens group and rear positive lens group and arranged to be zoomed by varying the airspace between the front and rear lens groups and to minimize variation of aberrations to be caused at the time of zooming.

Abstract: This invention relates to novel contact lenses, to a method of preparing the same, and to apparatus for carrying out the method of the invention.

Abstract: An air spaced etalon for wavelength selection including a spacer comprised of two hollow cylindrical members abutting each other in end-to-end aligned relation. A high degree of parallelism of two seconds or less can be easily obtained between the opposite end surfaces of the compound spacer by adjusting the relative angular position of the spacer members irrespective of the parallelism of the end surfaces of the individual spacer members. This enables production of high performance etalons with reduced cost and high yield.

Abstract: A low magnification microscope objective lens system which comprises a small number of lenses and wherein lateral chromatic aberration is controlled to a level similar to that in high magnification microscope objective lens systems while maintaining flatness of image.

Abstract: A miniature and large aperture wide-angle lens is composed of ten or eleven lenses grouped in nine lens components. In order from the object to the image side, the first lens component is a positive lens, and the second, third and fourth lens components are each negative meniscus lenses. The fifth lens components is a thick positive lens. The sixth lens component is a positive lens, and a diaphragm is disposed between the fifth and sixth lens components. The seventh lens component is a negative lens. The eighth lens component comprises a negative lens and a positive lens cemented together to form a positive lens. The ninth lens component comprises either one positive lens or two positive lenses.

Abstract: A zoom lens system in accordance with this invention is composed of a first fixed lens group, a first movable lens group, a second movable lens group and a second fixed lens group arranged in this order from front to rear, wherein a stop is are located at the center of the whole lens system and the first fixed lens group and the second fixed lens group consist of the same lens elements and located symmetrically with respect to the stop, and similarly the first movable lens group and the second movable lens group consist of the same lens elements and are located symmetrically with respect to the stop. The first movable lens and the second movable lens are asymmetrically moved with respect to the stop in accordance with the location of the whole lens system that is changed to vary the magnification, whereby the distortion and the focus shift caused by the field curvature fluctuation are eliminated throughout the variable range of magnification.

Abstract: This invention relates to an optical system for the production of a beam of light having a uniform intensity distribution. The optical system includes at least one Fresnel biprism for converting a beam of light having a non-uniform intensity distribution into a beam of light having a uniform intensity distribution.

Abstract: A wide angle zoom lens system for use with a 35 mm single lens reflex camera is provided. The zoom lens system is relatively compact and includes two lens groups that can be relatively displaced along the optical axis to provide variation in focal length as desired. The first lens group has a negative refractive power and the image side second lens group has a positive refractive power. The relationship of their refractive powers has been selected to provide adequate correction of aberrations while maintaining the size, weight and compactness required in a modern zoom lens system with wide angle capability.

Abstract: An interferometer system and process for detecting etch rates in opaque materials, such as silicon or metal, has means for producing a pair of parallel light beams, one of which is directed to the surface of the opaque material and the other of which is directed to the surface of an adjacent transparent masking material. The rate of etch of the opaque material is determined by detecting and recording the changes of light intensity due to interference between the beam reflected from the opaque layer and the beam reflected from the opaque layer beneath the transparent masking material.

Abstract: A microscope objective comprising a first, second, third and fourth lens components, in which the first lens component is a biconcave lens, the second lens component is a biconvex lens, the third lens component is a positive cemented meniscus doublet, the fourth lens component is a positive lens, and satisfying the following conditions for which N. A. is large, working distance is long and flatness of image is favorable.0.15<.vertline.r.sub.2 /r.sub.1 .vertline., 0.5<.vertline.r.sub.5 /r.sub.7 .vertline.<2.5 (1)0.4d.sub.4<d.sub.3 /n.sub.2 +d.sub.5 /n.sub.3 +d.sub.6 /n.sub.4 <3.5d.sub.4 (2)d.sub.2 <2.5d.sub.3 /n.sub.2 (3).nu..sub.1 >55, n.sub.1 <1.58 (4).nu..sub.2 <50, n.sub.2 >1.7035<.vertline..nu..sub.4 -.nu..sub.3 .vertline., .nu..sub.4 >60 (5)n.sub.3 <1.

Abstract: A variable magnification lens which can have its focal distance range easily changed and has a focusing lens group, a variable lens group and an imaging lens group positioned in said order from an object side, wherein said imaging lens group has a fixed front lens group, a movable middle lens group, a fixed rear lens group in said order from an object side, further an attachment lens is provided in a freely dismountable manner on an optical axis between said front lens group and the rear lens group, and when said attachment lens is mounted said middle lens group is shifted to a prescribed position, thus the focal distance range of the variable magnification lens will be different between a time when the attachment lens is mounted and a time when the same is not mounted.

Abstract: A large-aperture ultra-wide angle photographic lens system which have such a small lens diameter as to be compatible with filters designed for use with other lens systems and wherein various aberrations are favorably corrected.

Abstract: A zoom lens having a semi-field angle of between 12.6.degree. and 6.3.degree. capable of focusing at a 1:2 image-to-object distance ratio while providing a comfortable working range. The lens comprises a movable focusing group, a second stationary compensating group, two zooming groups which move axially relative to the lens and differentially of each other, and a fifth rear master group.

Abstract: A large aperture wide-angle photographic lens system is composed of ten lenses grouped in eight lens components. In order from the object side to the image side, the first lens is a positive lens, and the second and third lenses are negative meniscus lenses having their surfaces of higher curvature facing the image side. The fourth and fifth lenses form a cemented doublet, the fourth lens being a positive lens and the fifth lens being a negative lens. The sixth and seventh lenses also form a cemented doublet with the sixth lens and the seventh lens being positive and negative lenses, respectively. Both doublets are cemented at the surfaces of highest curvature. Each of the eight, ninth and tenth lenses are positive lenses.

Abstract: A common path interferometer is provided using one or more roof mirrors for effecting an optical path delay required to generate an interferogram of a target signature. The optical arrangement using the roof mirror separates the beam of radiation transmitted from the target to produce a fixed delay between the separated beams and, by rotating the roof mirror, a variable delay between the beams is obtained without leaving the target, thus generating an interferogram between the two interfering beams. The resultant interferogram is converted to a spectrum using conventional inverse Fourier transform techniques.

Abstract: A zoom lens system wherein the front lens group comprises, in order, a positive lens, a high power negative meniscus lens, a negative lens, and a high power positive lens. The relatively movable rear lens group comprises a plurality of lenses in front of and behind a double concave lens, including a double convex lens on the object side and at least two convex lenses on the image side. The various lens system parameters, including the minimum focal distance, the spacing between the front and rear lens groups, the maximum angle of incidence, the overall length of the system, the amount of back-focus zoom variation, and the magnification variation ratio, are selected to satisfy six different limiting conditions which balance an optimum miniaturization with a satisfactory aberration level.

Abstract: A system and method provides in situ measurements of the size of particulate matters suspended in fluid medium. A beam of intermittently interrupted electromagnetic radiation is directed through a portion of the fluid medium and radiation backscattered from a first optically defined region disposed within the fluid medium at a location having substantially uniform incident illumination is detected and utilized to provide an indication of the size and distribution of the suspended particles. To assist in assuring particles under surveillance are within the first region at the time the measurements are made, light backscattered from a further region disposed in the fluid medium and containing the first region is collected and compared with the intensity of the radiation backscattered from the first region prior to making the measurements.

Abstract: A telephoto lens assembly comprises a first positive lens, a second negative lens, third and fourth positive meniscus lenses having higher object side curvatures, a fifth negative lens, and a sixth positive lens adhered to the latter. The optical parameters of the lens components and assembly, including various composite focal distances, Abbe number products, and refractive index products, are chosen to satisfy prescribed, interrelated mathematical conditions to achieve satisfactory optical performance with an overall lens assembly length of less than 0.85 times the focal distance.

Abstract: A nephelometer including an optical excitation system for directing light through a first window area into a cylindrical glass container and an optical detection system for quantitatively monitoring light scattered by a substance within the container and passing therefrom through a second window area. The optical detection system includes a lens system in optical alignment with the second window area and focused on an optical dark region on an inner wall of the container opposite the second window area. The optical dark region is free of internal light reflections. Therefore, the light monitored by the detection system is scattered light from the substance substantially free of internal light reflections representing background error.

Abstract: This invention relates to a system for the calibration of an optical particle-size analyzer of the light-intercepting type for spherical particles, wherein a rotary wheel or disc is provided with radially-extending wires of differing diameters, each wire corresponding to a particular equivalent spherical particle diameter. These wires are passed at an appropriate frequency between the light source and the light detector of the analyzer. The reduction of light as received at the detector is a measure of the size of the wire, and the electronic signal may then be adjusted to provide the desired signal for corresponding spherical particles. This calibrator may be operated at any time without interrupting other processing.