Abstract: An endoscope has a tubular shaft in whose interior is arranged at least one component of an optical system. At least one support element made from a shrinkable material surrounds at least partially said component in a radial gap between the outer side of said component and the inner side of said tubular shaft. After shrinking of said support element the radial gap is filled up in a manner such that the component is immobilized on the inner side of the tubular shaft via the shrunken support element (FIG. 1).

Abstract: Optical systems for endoscopes, borescopes, dental scopes, and the like which are characterized by having three groups of lenses of positive optical power and an external entrance pupil. Typically, all three groups of lenses are displaced from the pupil and focal planes. As a consequence, the displaced groups take part in the image transfer as well as in the pupil transfer. The optical power requirements can thus be shifted from one group to amother, distributing as well as reducing the overall power requirement. Moreover, the aberration correction can also be shared between these groups. The first group, which conventionally has the highest optical power, and consequently a large amount of aberrations to be corrected, can in this way transfer some of the optical aberration correction to the other groups. The sharing of the optical functions and aberration correction results in a fully integrated optical system.

Abstract: A set of lens systems consisting of a plurality of different kinds of lens systems each comprising a radial type gradient index lens element(s), wherein the radial type gradient index lens elements have a common refractive index distribution.

Abstract: A variable magnification optical system comprises at least three optical units which are a first moving optical unit, a fixed optical unit and a second moving optical unit. The three optical units are arranged in that order in a propagation direction of light, and a variation of magnification is effected by a relative movement between the first moving optical unit and the second moving optical unit.

Abstract: An endoscope having a distally disposed lens and an optical transmission system which transmits the image of the lens to the proximal end of the endoscope is provided. The transmission system includes at least one reversing system, which includes two elements in mutual mirror-inverted arrangement. Each element includes a rod lens with planar faces and at least one optically thin lens having a planar surface. The rod lenses consist of an inhomogeneous material having a positive dispersion and an inhomogeneous refractive index in the radial direction, while the thin lenses are plano-convex lenses.

Abstract: A microscopic optical system which is used in an ultraviolet range of short wavelengths and has good off-axis performance, such as chromatic aberration of magnification. The optical system has an objective optical system for forming an intermediate image of a specimen and a relay optical system for imaging the intermediate image again. The relay optical system has a first lens group and a second lens group, and at least one convex lens of at lease one of the first and second lens groups is formed from quartz.

Abstract: A lens frame guiding mechanism of a zoom lens includes lens frames having projections which extend radially outwards, wherein a cam follower is formed on each projection; a linear guide barrel; linear guide slots formed on the linear guide barrel parallel to the optical axis, wherein the projections of each lens frame are respectively engaged in the linear guide slots to be slidable therealong; a cam barrel fitted outside the linear guide barrel to be relatively rotatable about the optical axis thereto; and bottomed cam grooves formed on an inner peripheral surface of the cam barrel, in which the cam followers of a corresponding lens frame are respectively engaged. The lens frames are moved in the direction of the optical axis, without rotating about the optical axis, to change a focal length of said zoom lens via rotation of said cam barrel.

Abstract: A binocular includes a hood, an eyepiece lens panel, and an objective lens panel. The hood has top, left side, and right side portions that are integrally formed. The left and right side portions have free edges that extend downwardly from the top to form an open bottom. The open bottom of the hood allows the hood to flex when an outwardly directed force is applied so that the left and right sides can be further separated from one another. This separation allows the eyepiece lens panel and the objective lens panel to be inserted within the hood during assembly of the binoculars to be held by the hood. The eyepiece lens panel has a flat plate frame and two lenses that are integrally formed as a one piece construction. The objective lens panel also has a flat plate frame and two lenses that are also integrally formed as one piece. The hood may further include alignment members to secure and align the eyepiece lens panel.

Abstract: A relay lens system used in an observation optical system which is to be disposed in an insert section is disclosed. The relay lens system comprises a plurality of relay lens units at least one of which allows longitudinal chromatic aberration to remain in an undercorrected tendency and at least another of which allows longitudinal chromatic aberration to remain in an overcorrected tendency, thereby correcting longitudinal chromatic aberration favorably in the relay lens system as a whole.

Abstract: A variable magnification optical system comprising four optical units each having a reflecting surface inclined with respect to a reference axis ray which is a ray passing from an aperture center of an aperture stop to a center of a final image plane, the variable magnification optical system being arranged to perform a magnification varying operation by moving at least two of the four optical units along the reference axis ray in such a manner as to vary an optical path length which extends along the reference axis ray from a predetermined position on an object side to the final image plane.

Abstract: A disposable rigid arthroscope having an inclined angle of view includes a frame member, an outer tube member extending distally from the frame member, an inner lens tube member eccentrically disposed within the outer tube member, an optical system disposed within the inner lens tube member and having a mechanism for altering the field of view of the optical system with respect to the optical axis and an illumination system including a plurality of optical fibers. The optical fibers of the illumination system are assembled and oriented to emit light in the general direction of the inclined field of view to sufficiently illuminate the surgical field. The materials of the arthroscope are advantageously selected to minimize the overall cost of the scope while providing for high level optical performance.

Abstract: An optical interconnect is formed form a series of coaxially aligned lenses. The lenses are spaced apart along a planar substrate and form repeated images of an optical array at the input to the interconnect. Outputs ports are located at different points along the interconnect. Each of the pair of lenses enclosing one of the repeated images is formed as a single physically integral member. This member may take the form of a transparent rod having spherical end surfaces. Each of the spherical end surfaces then provides one of the pair of lenses.

Abstract: A variable magnification optical system comprises at least three optical units which are a first moving optical unit, a fixed optical unit and a second moving optical unit. The three optical units are arranged in that order in a propagation direction of light, and a variation of magnification is effected by a relative movement between the first moving optical unit and the second moving optical unit.

Abstract: A photonic television system for propagating an image of light, in the form of its original three dimensional photonic makeup, through an airless, light proof, wave guide structure, utilizing a unique system of plastic concave and convex lenses in tandem, whose physical spacing is preferably one focal length from each other, which results in the photons of the image to be continually expanding and contracting, as they automatically propagate through each lens to the end of the wave guide, where via conventional magnifying lenses, the three dimensional image can be seen by a viewer, in a manner similar when viewing a microscope or telescope.

Abstract: The present invention provides a relay variable power optical system in a simple structure which is capable of suppressing a change of the position of the exit pupil on varying the power. To this end, the relay variable power optical system is provided with a front lens group G0 for condensing a light from a primary image, a variable power lens system (G1 to G3) for receiving the light from the front lens group G0, and performing zooming and a rear lens group G4 for forming the secondary image by condensing the light from the variable power lens system. When the zooming is performed from the high magnification end to the low magnification end, a distance between the first lens group G1 and the second lens group G2 and a distance between the second lens group G2 and the third lens group G3 are changed.

Abstract: A relay lens system used in an observation optical system which is to be disposed in an insert section is disclosed. The relay lens system comprises a plurality of relay lens units at least one of which allows longitudinal chromatic aberration to remain in an undercorrected tendency and at least another of which allows longitudinal chromatic aberration to remain in an overcorrected tendency, thereby correcting longitudinal chromatic aberration favorably in the relay lens system as a whole.

Abstract: A low cost optical viewing device includes an objective lens section, a relay lens section and an eye piece section. The relay lens section is devoid of glass rods and includes a minimal number of lenses each preferably fabricated from plastic material. The illumination system includes a plurality of optical fibers also preferably fabricated from plastic material.

Abstract: A lightweight night vision device that can be used by itself or can be selectively attached to either the objective lens assembly or ocular lens assembly of an existing optical device. The night vision device includes an image intensifier tube for amplifying low intensity light to produce a visible image. The image produced by the image intensifier tube is inverted. A prism assembly is positioned proximate to the image intensifier tube to reinvert the image in a space and cost efficient manner. The image intensifier tube, the power supply for the image intensifier tube and the reinverting prism are all contained within a house just large enough to accommodate these components. The housing has an objective port and an ocular port. Both ports are adapted to be joined to other optical components. As a result, a large variety of optical devices can be attached to either the object port or ocular port of the night vision device, thereby providing night vision capabilities to the optical device.

Abstract: An endoscope has an elongated sheath that follows a curved path. The sheath houses a plurality of relay lens sets designed to have a maximum usable field of view that is greater than the size of an image to be produced. Discrete lens elements within the image transfer guide allow the image to offset to the edges of the maximum usable field of view thereby to allow the axes through the individual sets to progressively shift in angle to form the curved path.

Abstract: A stereoscopic-vision endoscope of the present invention comprises a tubular elongated insertional part, an objective optical system situated in the insertional part, a relay optical system situated in the insertional part for transmitting an object image formed by the objective optical system, a pupil dividing stop for dividing a light beam emanating from an object image formed by the relay optical system into a plurality of portions, an image formation optical system for receiving light beams from the pupil dividing stop so as to form a plurality of object images having parallax, and imaging devices for picking up the object images formed by the image formation optical system. The relay optical system satisfies the condition .phi..sup.2 /L>0.43 (where .phi. denotes an outer diameter of a system of relay lenses, and L denotes a relay length of the relay optical system).

Abstract: Optical systems for endoscopes, borescopes, dental scopes, and the like which are characterized by having three groups of lenses of positive optical power and an external entrance pupil. Typically, all three groups of lenses are displaced from the pupil and focal planes. As a consequence, the displaced groups take part in the image transfer as well as in the pupil transfer. The optical power requirements can thus be shifted from one group to another, distributing as well as reducing the overall power requirement. Moreover, the aberration correction can also be shared between these groups. The first group, which conventionally has the highest optical power, and consequently a large amount of aberrations to be corrected, can in this way transfer some of the optical aberration correction to the other groups. The sharing of the optical functions and aberration correction results in a fully integrated optical system.

Abstract: An image transmission optical system comprising a relay lens system for a single image relaying cycle which has a magnification of approximately 1.times. and comprises at least one radial gradient-index lens element having a refractive index distribution expressed by the formula (a) shown below and satisfying the following condition (1), thereby favorably correcting logitudinal chromatic aberration produced by the relay lens system for a single image relaying cycle.N(r)=N.sub.00 +N.sub.10 r.sup.2 +N.sub.20 r.sup.4 + . . . (a)1/V.sub.10 <1/V.sub.

Abstract: An image transmitting optical system comprising at least two bar-shaped lens components and constructed to have a numerical aperture enlarged by reserving an adequate space between an image of object to be transmitted and one of surfaces of the bar-shaped lens component which is located closest to the image of the object. In this image transmitting optical system, spherical aberration and curvature of coma are corrected by designing each of the bar-shaped lens components as a cemented lens component consisting of two bar-shaped lens elements.

Abstract: A monolithic relay lens system for an endoscope is provided and includes a plurality of alternating individual polymeric lens elements bonded together with optical cement lenses of predetermined optical properties. In particular, multiple biconcave lenses of a first polymeric material are bonded to and alternated with multiple biconcave lenses of a second polymeric material by biconvex optical cement material lenses, in order to provide a monolithic and cylindrical achromatic optical structure. The polymeric lens elements of the system can be mass produced using injection molding. Low temperature polymeric material combinations, such as polystyrene and acrylic, are most easily injection molded and may, together with the optical cement, be used to manufacture disposable and very inexpensive relay lens systems. On the other hand, where a temperature resistant, autoclavable endoscope is preferred, high temperature polymeric lens combinations, such as polycarbonate and TPX can be used.

Abstract: A relay lens system to be incorporated in an endoscopic optical assembly is provided. The relay lens system includes at least one relay lens module for relaying an image between successive image planes. The relay lens module consists of two identical optical assemblies arranged in bilateral symmetrical relation relative to a median plane disposed between the two assemblies. Each optical assembly includes a glass plano cylinder and first and second curved lens components attached to each end of the plano cylinder. The lenses forming the lens components are fabricated from different optical materials including polymeric materials to correct aberrations within the system. The physical and geometrical characteristics of the components are selected to effectively transfer a bright image to the viewer.

Abstract: An optical system for a compound camera includes an equivalent image plane provided at a position substantially optically equivalent to an image plane of the photographing lens system. A condenser lens is provided proximate to the equivalent image plane and a relay lens system is provided behind the condenser lens to form an image of the photographing lens system on an image pickup device. The relay lens system satisfies the requirements defined by -0.1<P<0.09, and S3<0, where P designates the Petzval sum of the whole relay lens system when the focal length of the relay lens system is assumed to be 1.0, and S3 designates the astigmatism coefficient of the whole relay lens system when the focal length thereof is assumed to be 1.0, respectively.

Abstract: A low cost optical viewing device for viewing a remote location comprises three sections of an objective lens, relay lens and eye piece. However, in contrast to prior art optical viewing devices, all three sections of the present invention are free of conventional and relatively expensive glass rods. The preclusion of the glass rods leads to an overall lower cost (e.g., disposable) optical viewing device (e.g, borescope and endoscope). In addition, the optical viewing device of the present invention achieves lower cost by the use of a combination of molded plastic lenses and glass lenses. In accordance with still another important feature of this invention, the method of illuminating the remote location to be viewed is accomplished by using low cost plastic optical fibers which are twisted so that the field of illumination is increased and may be tailored to match (or be no less than) the size of the field of view of the optical viewing device.

Abstract: A telecentric relay lens system is provided with field lenses in the vicinity of an object and an image, respectively, at both sides of a centrally arranged lens member. In order to produce distortion the field lenses include cemented surfaces, the cemented surface of one of the field lenses being a collective surface, the cemented surface of the other of the field lenses, being oppositely arranged relative to the central lens member, being a diverging surface.

Abstract: A hard-type endoscope apparatus equipped with an inserting portion, a plurality of lenses inserted in the insertion portion, and a lens-barrel holding the lenses, includes a spacer pipe provided in the lens-barrel along the optical path of the lenses. The lens barrel is made of synthetic resin materials containing an additive. The additive forms matting irregularities on an inner surface of the tubular member.

Abstract: A relay lens system for an endoscope is provided and includes three axially aligned cylindrical lens pairs, each lens pair having two substantially rod-like lenses. Each rod-like lens includes a convexo-concave polymeric aspheric lens and a concavo-convex polymeric aspheric lens which are symmetrically placed and affixed about a glass rod with flat ends by means of plano-convex optical cement lens elements. The optical cement lens elements form lens-like elements which contribute to both the color and geometric aberration correction of the lens system. When inserted as a component of an endoscope or laparoscope, the distal end of the relay lens system is axially aligned with an objective lens and the proximal end is axially aligned with a viewing eyepiece. The image formed at the distal end of the endoscope by the objective lens is transmitted by the relay lens system, which inverts once and refocuses twice before forming a final upright image in front of the eyepiece for viewing or recording.

Abstract: An endoscope includes a disposable probe and a non-disposable focusing ocular. The probe includes a transfer module assembly including one or more relay modules, and an objective element including a distal glass window, a molded plastic prism and three molded plastic lenses. Each of the relay modules contains an entry glass rod, an intermediate glass rod, and an exit rod, each having flat end surfaces and two identical molded plastic doublets. The elements of the ocular are all of glass and include an axially movable focusing doublet and two non-movable doublets. The disposable probe introduces certain aberrations into the image. The non-disposable focusing ocular corrects these aberrations. A single curved surface is formed on the distal glass window of the probe; all other curved optical surfaces of the disposable probe are formed on molded plastic members, thereby reducing the cost of the probe sufficiently to be cost-effective for single patient, disposable use.

Abstract: An optical information transmitting device for transmitting information on a light beam emitted by a light source, includes an electronic circuit board, and an optical input/output port mounted on the electronic circuit board. The optical input/output port has a glass substrate attached to the electronic circuit board, a first array of optical sensors for absorbing a portion of a light beam applied thereto from the light source and photoelectrically converting the portion of the light beam, and for transmitting the remainder of the light beam therethrough, and a second array of spatial light modulators for modulating the transmittance with respect to a light beam applied thereto, the first and second arrays being disposed on a surface of the glass substrate in superposed relationship to each other.

Abstract: The present invention relates to a relay lens system, wherein all image aberrations are corrected. This permits modular use with no stand-alone lenses or lenses with great focal distance. The relay lens system comprises at least two subsystems, wherein at least one positive lens and at least one negative lens are placed in at least one subsystem near the intermediate image, and the refractive index N(+) of at least one positive lens and the refractive index N(-) of at least one negative lens and the total focal distance F(FLD) of the lenses of the subsystem near the intermediate image correspond to the following relations:N(+)>N(-)and F(FLD)>0.

Abstract: Radial gradient index of refraction (GRIN) optical relays for overcorrecting axial chromatic aberration and a method for their manufacture are described. A relay including a radial GRIN rod in combination with a holographic optical element, or simple homogeneous or GRIN lenses, is described for adjusting axial chromatic and monochromatic aberrations, including spherical, coma, astigmatism, and distortion. The invention also describes remote viewing scopes, such as endoscopes and borescopes, which utilize said relays for achromatic, and reduced or corrected monochromatic aberration imaging. The use of segmented said relays provides a slight degree of flexibility in certain remote viewing scopes. A method for producing an exemplary negative dispersion GRIN lens is disclosed.

Abstract: A collapsible terrestrial telescope having a lens system which includes an objective lens and a terrestrial eyepiece, wherein the eyepiece includes an erecting lens group, and an eyepiece lens. The objective lens and the erecting lens group each include an aspheric surface. The objective lens may be one of an optically interchangeable doublet including a positive element having the aspheric surface and a negative element, or a singlet having the aspheric surface and a diffractive surface.

Abstract: An optical rotation device with infinite depth of field for transmitting optical images along an optical axis and selectively rotating the image about the optical axis, while preserving all of the three dimensional characteristics of the image. The optical rotation device consists of two optical elements optically coupled in series, each of which produces an inversion of the image about an axis orthogonal to the optical axis. Rotation of the image by any angle in the plane normal to the optical axis is achieved by rotating the two optical elements relative to one another about the optical axis.

Abstract: A low cost optical viewing device for viewing a remote location comprises three sections of an objective lens, relay lens and eye piece wherein all three sections of the present invention are free of conventional and relatively expensive glass rods. The preclusion of the glass rods leads to an overall lower cost (e.g., disposable) optical viewing device (e.g, borescope and endoscope). In addition, the optical viewing device of the present invention achieves lower cost by the use of a combination of molded plastic lenses and glass lenses. In accordance with still another important feature of this invention, the method of illuminating the remote location to be viewed is accomplished by using low cost plastic optical fibers which are twisted so that the field of illumination is increased and may be tailored to match (or be no less than) the size of the field of view of the optical viewing device. Still another significant feature of the present invention is its low weight.

Abstract: An optical system to be incorporated in endoscopic instrumentation is provided. The optical system includes objective lens, relay lens and eye lens assemblies. The objective and eye lens assemblies are comprised of a plurality of axially aligned polymeric lenses. The relay lens assembly includes at least one relay lens module for transferring an image between successive image planes. The relay lens module consists of two identical optical assemblies arranged in bilateral symmetrical relation relative to a median plane. Each optical assembly includes a glass plano cylinder and polymeric curved lenses. The physical and geometrical characteristics of the components are selected to effectively transfer a bright image to the viewer.

Abstract: An endoscope is disclosed which is designed to transmit light to the area under observation and allows the light to make contact with the image plane, without the need of a fiber optic bundle. The ocular section of the endoscope, in addition to housing the lenses required to magnify the image for viewing, contains a relay lens whose diameter is less than the diameter of the rod lenses in the relay section. Light is then reflected through a beam director surrounding the ocular relay lens and transmitted to the objective through the excess diameter of the larger diameter relay lenses. Additionally, the ocular section is separable from the relay and objective sections, which are considered disposable, so that it can be reused.

Abstract: A ring lens assembly for an optical viewing device is presented. The ring lens assembly includes a ring shaped lens adapted for mounting at the end of an optical viewing device for viewing a remote location. The optical viewing device comprises an objective lens section, a relay lens section and an eye piece section. Further, the optical viewing device has an inner tube wherein the optics is housed and an outer tube. A plurality of optical fibers are disposed between the inner and outer tubes to provide illumination of the field of view. The ring shaped lens is a negative curvature lens or a prism-like lens for increasing the field of illumination. Alternatively, the lens is a flat lens and the optical fibers twisted to increase the field of illumination. Also, a cleaning tube is disposed between the inner and outer tubes. The cleaning tube terminates short of the end of the inner tube. An opening or channel is formed at the end of the inner tube adjacent to the cleaning tube.

Abstract: An optical information transmitting device for transmitting information on a light beam emitted by a light source, includes an electronic circuit board, and an optical input/output port mounted on the electronic circuit board. The optical input/output port has a glass substrate attached to the electronic circuit board, a first array of optical sensors for absorbing a portion of a light beam applied thereto from the light source and photoelectrically converting the portion of the light beam, and for transmitting the remainder of the light beam therethrough, and a second array of spatial light modulators for modulating the transmittance with respect to a light beam applied thereto, the first and second arrays being disposed on a surface of the glass substrate in superposed relationship to each other.

Abstract: A low cost optical viewing device for viewing a remote location comprises three sections of an objective lens, relay lens and eye piece. However, in contrast to prior art optical viewing devices, all three sections of the present invention are free of conventional and relatively expensive glass rods. The preclusion of the glass rods leads to an overall lower cost (e.g., disposable) optical viewing device (e.g., borescope and endoscope). In addition, the optical viewing device of the present invention achieves lower cost by the use of molded plastic lenses rather than the more expensive glass lenses used in prior art devices. In accordance with still another important feature of this invention, the method of illuminating the remote location to be viewed is accomplished by using low cost plastic optical fibers which are twisted so that the field of illumination is increased and may be tailored to match (or be no less than) the size of the field of view of the optical viewing device.

Abstract: An endoscope includes a disposable probe and a non-disposable focusing ocular. The probe includes a transfer module assembly including one or more relay modules, and an objective element including a distal glass window, a molded plastic prism and three molded plastic lenses. Each of the relay modules contains an entry glass rod, an intermediate glass rod, and an exit rod, each having flat end surfaces and two identical molded plastic doublets. The elements of the ocular are all of glass and include an axially movable focusing doublet and two non-movable doublets. The disposable probe introduces certain aberrations into the image. The non-disposable focusing ocular corrects these aberrations. A single curved surface is formed on the distal glass window of the probe; all other curved optical surfaces of the disposable probe are formed on molded plastic members, thereby reducing the cost of the probe sufficiently to be cost-effective for single patient, disposable use.

Abstract: A flexible light conduit which preserves the coherence of a transmitted beam. Several conduit elements having optical elements mounted inside each one are connected together to form a chain. Each conduit element is tiltably coupled to each adjacent conduit element in the chain. The optical elements may be refractive or reflective. The conduit preserves the spatial coherence properties of the beam so the input image is reimaged at a distant place, having passed through the series of relay optical elements through the angles permitted by the coupling members.

Abstract: The present invention is an image intensifier assembly that includes a Generation III image intensifier tube and an inverter lens arrangement, such that the present invention image intensifier assembly can be substituted for a Generation II image intensifier tube in a given application. The inverter lens arrangement is adjustably positionable relative to the Generation III image intensifier tube so the image relayed can be focused to optimize the resolution of the complete tube assembly.

Abstract: A panoramic imaging system is formed from select configurations of micro-optic multiplets (MOM) comprised of two microlens modules (MLM). The MLMs themselves are formed from arrays of microlenses. The present panoramic imaging system is characterized by the two MLMs configured on concentric approximately spherical surfaces. The optic axis of each of the microlenses is tilted slightly with respect to its neighbor to allow for proper alignment of images to form a single primary image on a substantially spherical global image surface.

Abstract: The visual accident prevention system relates to accident prevention through the use of a lens system, a fiberoptic cable system and a display device system. A lens system is placed on each side of the vehicle, at the very least, on the front portion of the vehicle, and, preferably, on the front portion and on the rear portion of the vehicle. Each of these lens systems have a fiberoptic cable system leading from the lens system to the lens system's corresponding display device. Each of these display devices when considered, in toto, form the display device system. Each lens system consists of a converging lens which receives the image from the blind spot which corresponds to the lens system's position on the vehicle. This converging lens reduces the image size and outputs this reduced size image to the diverging lens on which the converging lens abuts.

Abstract: A variety of optical systems can be formed from select configurations of micro-optic multiplets (MOM) comprised of two or more microlens modules (MLM). The MLMs themselves are formed from planar arrays of microlenses. An optical system configured in accordance with the present invention forms a single primary image, together with a set of images transversely displaced from an optic axis and is characterized by the property that the image distance and the object distance move in the same direction, in stark contrast to known lens systems. For example, when an object distance decreases, the corresponding image distance also decreases with the present optical system.

Abstract: An improved endoscope employing phase conjugate imaging principles includes a first transmissive member for transmitting light rays received at a distal tip of the endoscope to an intermediate filter location. A phase conjugate filter at the intermediate filter location redirects the rays, according to the precise inverse of their incoming direction, along a second transmissive member optically identical to the first. Rays exiting the endoscope bear the exact relation to one another as when entering the tip of the endoscope and may be imaged or displayed on an eyepiece or video screen.

Abstract: In this system a module carries an afocal variator optical system, and to which module a front partially-obscured reflecting telescopical system and a rear system module can be substantially permanently connected in combination to vary the actual focal length of the front partially-obscured reflecting telescopical system in conjunction with a rear system module without the need to physically change the length dimension of any system, or without the need to change the mirror position or positions of the front module. A partially-obscured reflecting telescopical system is defined as any selected from the group Newtonian, Cassegrain, Ritchey-Chretien, Gregorian and any of their derivatives, including catadioptric derivatives, such as Maksutov and Schmidt types, in which the incoming light is obscured by a central disk with reflecting obverse side, diagonal mirror or pickoff mirror essentially on-axis to the incoming light.