Abstract: This patent teaches a low cost imager. The imager has an refractive objective lens 10 having a surface with a color correcting diffractive pattern 16 and an infrared transmitting polymeric field lens 18 having a substantially flat surface with a first field-correcting diffractive pattern. In this imager, the first field-correcting diffractive pattern operates to reduce aberrations of an image. In some embodiments, the imager further has a second field-correcting diffractive pattern on the field lens, where the first and second field-correcting diffractive pattern cooperating to reduce aberrations of the image. Additionally, this patent teaches a refractive/diffractive achromatic lens group 30. This achromat 30 can be used in the disclosed imager or in other optical devices. The achromatic group 30 has a refractive lens 10 and a lens 28 having a substantially flat surface with a surface diffractive pattern 16, the surface diffractive pattern cooperating with the refractive lens to reduce chromatic aberrations.

Abstract: An image detection system (10) uses an optical configuration for both image forming and calibration phases of operation. A field lens (20) has an inner portion (36) of a conventional prescription to allow for collection of scene based energy for an opto-electronic approximation of the infrared detail within the afocal field of view by a focal plane array (32). The field lens (20) also has an outer portion (38) that collects far field energy from a scene area (A.sub.I) through a converging point (P.sub.I). The energy collected from the scene area (A.sub.I) is indicative of the average energy level within the scene. The electrical equivalent values of all energy received from the unique area (A.sub.I) is stored in a multidimensional range used for subsequent gain and offset calibration coefficient calculations.

Abstract: Dual channel Endodiagnostic apparatus and methods by which infrared emissions within the range including 2 to 14 micrometers may be visualized in the form of encoded images to permit differential analysis. The endoscopic apparatus has an IR channel and a visible channel. The IR channel comprises a refractive objective lens for forming a real image of interior structure of interest, a relay system consisting solely of refracting elements for transferring the real image to an intermediate image plane conjugate to the objective image plane, and a refracting coupling lens for forming a final image of the intermediate image in a detector plane in which an IR detector sensitive in the range including 2 to 14 micrometers may be placed near the proximal end of the apparatus. The IR and visible channels are arranged to visualize substantially the same subject matter.

Abstract: An achrathermalized reimager includes a front objective defining an optical axis and a relay optic arranged on the optical axis downstream of the front objective. The front objective is both achromatic and athermalized and includes precisely one negative lens made of a material selected from the group consisting of ZnSe and ZnS and one positive lens made of chalcogenide glass.

Abstract: A remotely controllable and programmable power control unit for controlling and programming the state and power level, including special functions, of one or more electrical devices. The electrical device can be an electric lamp. The system includes a user-actuatable remote transmitter unit and a user-actuatable power control unit adapted to receive control signals from the remote transmitter unit. Both the remote transmitter unit and the power control unit include a power selection actuator for selecting a desired power level between a minimum power level and a maximum power level, and control switches for generating control signals representative of programmed power levels of one or more power scenes and special functions. In response to an input from a user, either directly or remotely, the one or more devices of the one or more power scenes can be controlled between an on or off state, to a desired programmed preset, or to a maximum power level.

Abstract: An optical system for use in an infrared camera which includes, in order from an object side: a first lens group having a negative refractive power and a second lens group having a positive refractive power arranged a distance from the first lens group. The first lens group comprises a negative meniscus lens having a convex surface facing toward the object side and the second lens group comprising, in order from the object side: a first lens having a positive refractive power, a second lens having a negative refractive power and a third lens having a positive refractive power. The lenses comply with the following conditions: (1) 0.5.PHI.<-.PHI.f<0.7.PHI., (2) 0.55.PHI.<.PHI.r<0.87.PHI., (3) 1.55 (1/.PHI.)<d<1.98 (1/.PHI.) and (4) dr<2.1 (1/.PHI.). The conditions are defined by: .PHI.: is the overall refractive power for the overall optical system for the infrared camera, .PHI.f: is the refractive power for the first lens group, .PHI.

Abstract: A low cost objective lens system that provides complete axial color correction with no substantial residual color dependent aberrations such as spherochromatism or chromatic coma. The objective lens system includes a first lens element having an aspherical lens surface and a second lens element having a diffractive optical surface and an aperture disposed between the first and second lens elements. The axial separation of the aspherical lens surface and the diffractive optical surface may be determined by the condition 0.5<L.sub.A /efl<1.25 where L.sub.A is the axial distance from the lens element with the aspherical surface to the lens element with the diffractive optical surface and efl is the effective focal length of the objective lens system. The diffractive optical surface is optically dispersive and is preferably placed on the refractive lens element in the system having the highest optical power.

Abstract: The focal length of an objective lens system is substantially equal at two wavelengths: one within the visible spectrum and one within an eyesafe IR spectrum centered about 1.54 .mu.m; the lens is essentially achromatic throughout the entire visible spectrum (0.45 .mu.m -0.70 .mu.m) and is well-corrected for other monochromatic aberrations (spherical aberration, coma, astigmatism, field curvature, and distortion). By having an objective lens that is common to both optical paths (visual and laser) and has the property of having essentially the same focal length and essentially the same angular deviation for the two optical paths upon lens decentration, then a practical mechanism can be included in the opto-mechanical design of a laser rangefinder to adjust the x and y decentration of the objective lens to accomplish a corresponding x and y adjustment of the system boresight.

Abstract: In a multi-lens infrared objective with wide band chromatic correction, more particularly in the spectral range from 1.4 to 5 .mu.m silicon is employed as a material for lenses with a negative focal length. In this respect the lenses consist of materials, which as regards their dispersion curves are selected from three different material group, of which the first material group comprises materials, whose short wave absorption bands are relatively close to the shortest wavelength to be corrected, the second group comprises materials, whose long wave absorption bands are closer to the spectral range to be corrected than the short wave ones and the third group comprises materials, whose relative absorption band positions are between the materials of the first and second groups.

Abstract: Endodiagnostic apparatus and methods by which infrared emissions of 2 micrometers and above may be visualized in the form of encoded images to permit differential analysis. The endoscopic apparatus comprises a refractive objective lens for forming a real image of interior structure of interest, a relay system consisting solely of refractive elements for transferring the real image to an intermediate plane conjugate to the objective image plane, a refracting coupling lens for forming a final image of the intermediate image in a detector plane in which an IR detector sensitive in the range of 2 micrometers and greater may be placed near the proximal end of the apparatus, and a warm stop for ameliorating the effects of stray IR radiation in the system.

Abstract: A solid catadioptric lens (10) includes substantially planar input surface (14), primary concave mirror 18, secondary convex mirror (22) and substantially spherical exit surface (24). The lens is composed of solid material (12) chosen according to the particular imaging application in which the lens is to be used. Radiation enters lens through input surface (14), travels through solid material (12) and is reflected off of primary mirror (18). Radiation subsequently passes internally through solid material (12) and is reflected off of secondary mirror (22). Subsequent to being reflected off of secondary mirror (22), radiation (30) passes through solid material (12) and out of lens (10) through spherical exit surface (24) and onto detector array (34) for imaging purposes.

Abstract: Multi-spectral images are detected using a refractive objective lens system. Magnesium oxide (MgO) and calcium fluoride (CaF.sub.2) lenses are used to image scenes in both the visible and infra-red (IR) spectrums. The inventors have discovered that the combination of magnesium oxide, only recently made available in a pure crystal form, and calcium fluoride can be used to fabricate an objective lens for imaging objects in both the visible and infra-red spectrums. Moreover, the combination of magnesium oxide and calcium fluoride results in a super-achromatic condition across visible and infra-red spectrums. This chromatically-corrected spectral range includes wavelengths between 0.4 and 5.9 microns which covers medium-wave IR (MWIR), short-wave IR (SWIR), and the near-IR/visible windows. Combinations of MgO and CaF.sub.2 lenses are used in different compound objective lens designs including doublet, Petzval, inverted telephoto, and telephoto arrangements.

Abstract: A dual-band optical system 10 preferably for use in the thermal infrared waveband provides initial detection of a target in a first waveband (8-12 .mu.m) having a wide field of view and discriminated target recognition in the second waveband (3-5 .mu.m) at higher magnification and narrow field of view without any field-of-view change mechanism. The system 10 comprises a detector array 11 which is responsive in both wavebands and an optical arrangement 16 with a common objective component 15 for both wavabands. One waveband is transmitted through dichroic beamsplitters 17,18 to the array 11 whereas the other waveband is reflected by the beamsplitters 17,18 and transmitted through a field lens 28 before reaching the array 11. Both wavebands are incident upon a spectrally selective aperture stop 20 providing a large aperture for the low magnification field and a small aperture for the high magnification field.

Abstract: An image detection system (10) uses an optical configuration for both image forming and calibration phases of operation. A field lens (20) has an inner portion (36) of a conventional prescription to allow for collection of scene based energy for an opto-electronic approximation of the infrared detail within the afocal field of view by a focal plane array (32). The field lens (20) also has an outer portion (38) that collects far field energy from a scene area (A.sub.I) through a converging point (P.sub.I). The energy collected from the scene area (A.sub.I) is indicative of the average energy level within the scene. The electrical equivalent values of all energy received from the unique area (A.sub.I) is stored in a multidimensional range used for subsequent gain and offset calibration coefficient calculations.

Abstract: A low weight, achromatic, athermal, long wave infrared objective lens with one element having a positive optical power and the other element having a negative optical power but with a higher thermo-optic coefficient than the thermo-optic coefficient of the first element. A diffractive color correcting optical surface is generated on one surface of one of the elements and aspheric surfaces may be included for further performance gains.

Abstract: Endodiagnostic apparatus and methods by which infrared emissions within the range including 2 to 14 micrometers may be visualized in the form of encoded images to permit differential analysis. The endoseopic apparatus comprises a refractive objective lens for forming a real image of interior structure of interest, a relay system consisting solely of refracting elements for transferring the real image to an intermediate image plane conjugate to the objective image plane, and a refracting coupling lens for forming a final image of the intermediate image in a detector plane in which an IR detector sensitive in the range including 2 to 14 micrometers may be placed near the proximal end of the apparatus.

Abstract: A lens system with a liquid optical element is for use in the mid-wave infrared from 3.0 micron to 5.0 micron wavelength is described. Using a liquid optical element which is highly transmissive in the 3.0 micron to 5.0 micron waveband of interest in conjunction with a solid material which is also highly transmissive in that waveband provides a lens design with very good optical performance which is less expensive and which is much lighter in weight than an all solid design of the same optical performance.

Abstract: The surface of a zinc selenide substrate is ground to curve in the opposite direction from that which occurs due to the bimetallic effect when zinc sulfide is deposited on a flat substrate by the chemical vapor deposition process. The bowing of the interface that occurs upon cooling of the hot laminate when the surface of the substrate is flat before deposition is compensated for by the pre-figured bowing. A distortion free window for the transmission of infra-red radiation is provided by this invention.

Abstract: A dioptric lens system comprises a plurality of lenses and a rear diaphragm functioning as an aperture diaphragm. An overall length in the order of the focal distance is obtained by the features that the object side surface of the object side lens comprises an aspherical component and that the intermediate and image side lenses are closely adjacent.

Abstract: An imaging system (10) contains a diffractive optic lens (14) which allows for a relatively accurate representation of objects within a field of view. These objects are associated with light rays (20, 22 and 24) which are made to impinge upon the diffractive optic lens (14) and thereafter are made to be received by an imaging surface (12) at a receiving angle which may be determined by the structure of the diffractive optic lens (14). The diffractive optic lens (14) may be placed within the typical dewar (16) of the image acquisition system (10), may be removable deployed over the imaging surface (12), or alternatively, the diffractive optic lens may be etched upon the front side of the imaging surface (12) by the use of standard etching techniques such as lithography, diamond turning and the like.

Abstract: A polymeric infrared window (10) is described which comprises a sheet of polymeric material (14). Sheet 14 further may comprise a layer of molecular weave polymer material (34) fixed to a electromagnetic interference shield (32). In addition, a polymeric sheet (42) may be embossed with a binary defractive pattern (40) to create a polymeric defractive lens (38).

Abstract: An optical low-pass filter includes an optical member formed of a material capable of absorbing light in a particular wavelength range, e.g., an infrared range. The optical member has a plurality of ridge-like portions formed on at least one surface thereof at a predetermined pitch. The ridge-like portions comprise a phase type diffraction grating which has a low-pass filtering effect with respect to bundles of optical transmission rays passing therethrough.

Abstract: The infra-red diffractive optical lens will remedy chromatism faults and offer excellent compactness; in addition, it does not call for a cooling device. It comprises a first convergent lens made of a material corresponding to the operational infra-red band width considered and a second convergent lens formed by a surface hologram. This hologram is obtained by accurate machining of one of the diopters of the first convergent lens according to machining data optimized by digital calculations. The first lens is preferably made of zinc sulfide. This system can operate simultaneously in the 8 to 12 microns infra-red band and the 1.06 microns laser channel.

Abstract: Design forms are disclosed for infrared imaging systems that can operate at hyper-hemispherical fields of view (e.g., up to 270.degree.) and at wide relative apertures (e.g., up to f/0.7) to produce images having low distortion--typically no more than 20% greater than the distortion resulting when the image size is proportional to the field angle.

Abstract: In an infrared (IR) microscope for a Fourier transform (FT) infrared spectrometer with a Cassegrain mirror-lens with which an incident beam (15) can be focused via a convex mirror (16) and a concave mirror (17) onto a first point-shaped region (19) on the surface of a sample (20) under an angle of incidence .beta.<60.degree.

Abstract: Lens systems (68, 78, 88, 98, 108, 118) with first and second rigid lens elements (70,71;80,81;90,91;100,101;110,111;120,121) and a liquid lens element (76, 86, 96, 106, 116, 126) therebetween are provided. The first and second rigid lens elements and the liquid lens elements co-act with each other to cause the lens system to have substantially diffraction limited performance over a continuous infrared wavelength band, wherein the first and second rigid lens elements and the liquid lens element are configured and positioned with respect to each other according to a selection of particular designs and design forms.

Abstract: In an infrared wide-angle single lens which is as constructed as of a positive meniscus lens, the following conditional expressions (1) through (6) are satisfied:(1) -50.0 th<r.sub.1 <-3.5 th(2) -5 th<r.sub.2 <-1.1 th(3) 2<n<4.5(4) 0.1 f<d<0.8 f(5) 0.5 f<bf<1.5 f(6) 0.5 f<th<2fwhere, an aperture stop is disposed between an object plane and a first surface, d is the distance between the aperture stop and the first surface, th is the lens thickness, bf is the backfocus, r.sub.1 is the radius of curvature of the first surface of the lens, r.sub.2 is the radius of curvature of a second surface of the lens, n is the refractive index of a vitric material of the lens at a wavelength of 10 .mu.m, and f is the focal length.

Abstract: Design forms are disclosed for wide-field infrared imaging systems characterized by a large ratio of entrance aperture to focal length, where the limiting aperture stop is located in the converging image space.

Abstract: Chromatic dispersion between first and second wavelengths of light is corrected by a lens/zone plate combination. The zone plate is adapted both to send most of the first wavelength light into its zeroth order and to send most of the second wavelength light into its first order and to change the focal length of the second wavelength light to coincide with the focal length of the first wavelength light. A preferred embodiment includes a zinc/selinide sulfide lens having a zone plate etched onto one of its surfaces. The zone plate has a multi-step phase profile including four phase levels. The lens/zone plate combination is particularly adapted for use with CO.sub.2 and HeNe lasers to bring their focal lengths into coincidence.

Abstract: An infrared-rejecting device is positioned in a light path and tilted thereto to reflect infrared radiation and to prevent infrared radiation from being applied to a photodetector or a line sensor for preventing the photodetector or the line sensor from operating in error or from suffering a reduction in its resolution. The infrared-rejecting device may be positioned out of the light path to allow light applied to the photodetector or the line sensor to remain unattenuated, i.e., to prevent the light applied to the photodetector or the line sensor from being reduced in intensity.

Abstract: A compound lens for use in a low light level system operating in the near-infrared region. The lens system includes a high light-gathering ability requiring both a large aperture and good transmissivity over the wavelengths of interest. A wide field of view (e.g., 50.degree.) without excessive chromatic and geometric aberrations that generally accompanies systems with a large aperture is provided. Space is provided in the lens system for a variable iris and variable density spot subassembly. Desired optical quantities are obtained through the use of zinc selenide as the material for an aspheric lens. The use of this diamond-turnable infrared material as a field lens yields exceptional performance for a fast (e.g., F/1.25) lens with a wide field of view.

Abstract: An optical system (10) includes a three mirror anastigmat telescope (12) and imager optics (14). The imager optics (14) provide narrow and wide field of view staring of the viewed scene. The optical system is positioned in a turret assembly (50) and folded to provide a sensor. The sensor includes an output laser beam generator (90). The telescope (12) is shared by the infrared system and the laser (90) to provide a simplistic and compact turret arrangement (50) which is well suited for aircraft targeting and designation purposes.

Abstract: An infrared-transmissive lens formed by using glass including germanium and selenium or germanium and sulfur as main components and a human body detecting device including the lens and a pyroelectric infrared sensor are disclosed. With this configuration, glass having excellent transmissivity of infrared rays, no poisonous characteristic and difficulty to be crystallized is obtained and the glass is subjected to thermal pressing work to form a lens. The lens and a pyroelectric infrared sensor are combined to obtain a scanning type human body detecting sensor device. Further, the scanning type human body detecting sensor device can be used to detect a plurality of human bodies simultaneously.

Abstract: An optical filter for absorbing neodymium YAG-doubled laser radiation at 532 nanometers, comprising a polymeric matrix of transparent polycarbonate containing platinum deuteroporphyrin IX dimethyl ester, has an optical density of 1.8 at 532 nm while having a photopic luminous visible transmission of 53.8%. Optionally, the filter may contain other additives for absorption at other laser wavelengths, such as vanadyl tetra-4-tert-butylphthalocyanine for absorption of ruby laser radiation at 694 nanometers and tris(p-diethylaminophenyl)aminium hexafluoroantimonate for absorption of neodymium YAG laser radiation at 1064 nanometers.

Abstract: A solid state form of a dye-solution absorption filter is disclosed. Physical vapor depositable (i.e., evaporable) dyes are codeposited with a polyester matrix in a vacuum system to randomly disperse dye molecules in a solid dilutant. The dyes are selected to absorb at the wavelengths of interest. Dilution in a transparent matrix affords narrow band absorption and good out of band transmittance. Multilayer configurations allow absorption of a plurality of wavelengths. The filter coating conforms to curved and sharply contoured surfaces and layers only 10 microns thick afford very high absorptance.

Abstract: A re-imaging optical system (36) is provided which utilizes a combination of refractive and diffractive optical elements. The system includes an objective lens group (38) for focusing an incoming beam of light to a first image plane. A relay lens group (40) refocuses the beam of light in a second image plane after it passes through the first image plane. The relay lens group (40) includes a diffractive optical element (48) for correcting aberrations introduced by the objective and relay lens groups. The diffractive optical element (48) eliminates a number of individual optical elements which would otherwise be required to correct aberrations, thereby reducing the total number of optical elements in the system. In the preferred embodiment, the diffractive optical element (48) comprises a binary optical element. The resulting system yields better image quality, better throughput, and a lighter, less bulky, re-imaging optical system (36).

Abstract: A finger mounted laser spotlight is constructed of a near-infrared continuous wave laser diode powered by a miniature power supply powered in turn by a nine volt battery. The laser diode is mounted inside a cylindrical heat sink housing which includes a focusable lens assembly. A momentary switch is connected in-between the power supply and battery. Cables interconnecting the components are sized to preselected lengths so that, when the power supply and battery are positioned over a wrist or other portion of the arm behind the fingers, the laser diode and housing are positioned over an index finger and the momentary switch is positioned between a thumb and index finger. In use, the momentary switch is pressed and held to provide a beam of near-infrared light.

Abstract: A three-lens objective has the following characteristics: A front lens consists of a first material of relatively low dispersion, a median lens consists of a second material of relatively larger dispersion, and a rear lens consists of a material of relatively low dispersion. The front lens has positive power, the median lens has negative power, and the rear lens has positive power. The spacing between front lens and median lens is substantially smaller than the distance between median lens and rear lens. Each of the lenses has at least one aspherical surface.

Abstract: An infrared optical part comprised of a synthetic diamond single crystal, and a method of making the same. The infrared optical part is comprised of a synthetic diamond having a nitrogen content of not more than 5 ppm and a boron content of not more than 3 ppm, wherein the parallelism between its light incident and reflecting surfaces is not more than one minute. The infrared optical part is used as a window member in infrared spectral analysis. It is also used in the form of a pair of anvils for holding a sample therebetween in connection with the measurement of transmitted light that has passed through the sample after the sample is compressed. The part is also used in the form of an infrared ATR prism.

Abstract: A plate or a sheet being capable of absorbing near IR-rays, which is prepared by heating both at least a raw material of a transparent polymer and a mixture of a thiourea compound and a copper compound. This invention provides superior optical materials for shielding sunlight thermic rays, better information recording materials and the like.

Abstract: A focus compensating lens structure wherein a lens means for collimating laser light produced by a source has an index of refraction which varies with temperature and wavelength to compensate for temperature effects on the wavelength of light produced by the laser source and the length of the mounting on which the source and lens are disposed.

Abstract: An accessory lens for a far-infrared thermal imager which is quickly insted or removed to double the range. The accessory uses two or three element with alternating dielectric constants and combinations of spherical and aspherical surfaces.

Abstract: Apparatus and a method for performing high resolution optical imaging in the near infrared of internal features of semiconductor wafers uses an optical device made from a material having a high index of refraction and held in very close proximity to the wafer. The optical device may either be a prism or a plano-convex lens. The plano-convex lens may be held in contact with the wafer or separated from the wafer via an air bearing or an optical coupling fluid to allow the sample to be navigated beneath the lens. The lens may be used in a number of optical instruments such as a bright field microscope, a Schlieren microscope, a dark field microscope, a Linnik interferometer, a Raman spectroscope and an absorption spectroscope.

Abstract: An infrared objective device with optical achromatization and athermalization comprises a front convergent assembly having at least one divergent lens acting as a port and one convergent lens, and a rear divergent assembly comprising at least one divergent lens. These three lenses are chosen so as to be made of three different materials of the type that can be used in the 8 to 12 .mu.m spectral band. They may notably be made, respectively, of germanium, chalcogenide and zinc sulphide.

Abstract: Esters of .alpha.-fluoroacrylic acid are accessible by hydrolysis of an .alpha.-hydroxymethyl-.alpha.-fluoromalonic acid ester, decarboxylation and dehydration of the hydrolysis product and subsequent esterification of the resulting .alpha.-fluoroacrylic acid with an alcohol. The esters are polymerizable and are suitable for use as a starting material for preparing fluoropolymers which in turn are usable as materials for manufacturing transparent articles. The polymers are high-molecular and non-crystalline and have softening temperatures of above 100.degree. C.

Abstract: An optical system for use in a medical laser apparatus comprising an achromat having optical elements selected to cause two substantially different wavelengths, one visible and one infrared, to focus at a common focal point. The achromat comprises a negative lens and a doublet lens formed of a positive bi-convex lens and a negative meniscus lens. The materials of the two lenses which form the doublet have substantially different dispersions and indices of refraction and are chosen to cause a visible helium neon beam and an infrared carbon dioxide beam to focus at the same point. In the preferred embodiment of the present invention, the negative lens is made of zinc selenide, the bi-convex lens of the doublet is made of potassium chloride, and the negative meniscus is made of zinc selenide. The optical system of the present invention can be mounted in a micromanipulator for use in laser surgery.

Abstract: A portable missile launcher has an optical system with a single lens (22) for receiving visible and near infrared light energy from a target (14) directing it to a prism (24) where the light is split into a part transmitted to an eyepiece (28) and a further part (30) to infrared tracking equipment (18). The objective lens (22) is a doublet having a front lens (32) and a rear lens (41) which cooperate to provide sufficiently small chormatic aberration to enable image quality correction for both visual examination and near infrared tracking.

Abstract: An optical system (10) for portable missile launcher (23) includes an objective lens (12) for receiving the entire visual and near infrared light energy emanating from a target (14) and immediate background of the target. The light energy from the objective lens then passes through a Porro prism assembly (16) which acts to direct visual light along a first path to an eyepiece (20) and near infrared along a second path at approximately a right angle to the first path where it is received by a tracker assembly (22) and monitored. The Porro prism (16) is constructed in accordance with this invention to include a multi-layer interference dichroic coating (18) disposed between the two prisms (34,36) which make up the prism assembly. This coating is of such a nature as to readily permit light energy in the visual range to pass directly through the coating, but at the same time to reflect the near infrared components along a second path bringing them to focus on the tracker assembly (22).

Abstract: A hydrophilic contact lens is disclsoed incorporating melanin that protects the eye from harmful radiation and superoxide.

Abstract: In order to enable to sufficiently deflect the viewing direction for a distal end having an end surface substantially perpendicular to the optical axis of an objective optical system and minimize aberrations produced due to the deflecting action, the objective optical system for endoscopes comprises at least one surface designed as a deflecting surface or an eccentric surface on the image side of the surface nearest the object to be observed out of the surfaces of the optical components composing the objective optical system so that the light is refracted at least twice for deflecting the viewing direction.