Abstract: An apparatus for detecting the in-focusing conditions for use in an optical machinery such as cameras, microscopes or endoscopes is disclosed. The apparatus comprises a light receiver arranged with an angle of inclination against an image surface of an optical system and consisting of a plurality of charge transfer elements aligned as a picture element array; means for deriving illuminance signals from the picture element array of the light receiver and means for treating the illuminance signals to detect the in-focused position of the optical system.

Abstract: An automatic focus adjusting device comprises an optical system for forming the image of a sample to be examined at the image formation point, a first image sensor disposed at a first position for receiving the light image of the sample and converting it into an electrical signal, a second image sensor disposed at a second position for receiving the light image of the sample and converting it into an electrical signal, signal processing systems for processing the signals from the first and second image sensors, and a servo device for controlling the vertical position of the sample relative to the image forming optical system.

Abstract: Range finding equipment for use with optical systems and particularly low cost cameras to provide for proper focus of a remote object. A small number of radiation detectors are positioned to receive radiation in first and second patterns from the object to be focused upon through an auxiliary lens. The outputs of the detectors are processed to produce a resultant signal which is indicative of the position for proper focus. The auxiliary lens is coupled to the taking lens of the camera and means are provided for moving both lenses in accordance with the resultant signal so that the taking lens is in a proper focus position. The detectors may be photo diodes to facilitate the use of log signals to thereby compensate for differences in intensity of the scene being viewed.

Abstract: A focus detecting device for a camera in which a portion of the light passing through a photographing lens is reflected to a first surface of a plane plate of transparent material. After passing through the plane plate, the beam is split by a half-silvered mirror with one beam emerging from the half-silvered mirror and plane plate while the other is reflected back through the plane plate towards the first surface. At the first surface, the second beam is reflected back again through the plane plate emerging therefrom at a point removed from the half-silvered mirror striking a second sensor located in the same plane as the first sensor. The outputs from the sensors, which are preferably linear arrays of photodiodes, are processed to provide a focus detecting signal which is further processed to provide signals indicating front focus, correct focus and rear focus.

Abstract: The invention relates to an arrangement for automatically focusing the image of an object, obtained by an objective lens system, onto an image plane by adjustment of the distance of the objective lens system or a portion thereof from such image plane. Two optical devices which are mutually offset transversely to the optical axis, are provided for obtaining auxiliary images of the object, which are photoelectrically analyzed with respect to one another. The minimum difference signal therebetween indicates the congruency of the two auxiliary images and supplies an adjustment criterion for a device operative to correspondingly adjust the objective distance. The invention utilizes two CTD image sensors to analyze the auxiliary images with the read-out signals being supplied to a differential amplifier and subsequently rectified and integrated.

Abstract: In a focus detecting device having a first and second photoelectric element arrays each including a plurality of photo-electric elements disposed so as to mutually correspond in position and optical means for forming a first image and a second image of an object on the first and second arrays, respectively, there is provided first means for calculating the differences between electrical outputs related to the outputs of the mutually corresponding ones of the photoelectric elements of the first and second arrays and adding together the quantities based on said differences, second means for calculating the difference between each electrical output related to the output of each of the photoelectric elements and each electrical output related to the output of the photoelectric element spaced apart from each photoelectric element with a predetermined number of photoelectric elements interposed therebetween in the direction of arrangement of the elements of the arrays and adding together the quantities based on sai

Abstract: An optical information system is provided with an optical focussing device for adjusting a position of an objective lens. The optical focussing device is comprised of a photosensing unit to which a part of a light beam reflected from a disc and passed through the objective lens is projected through a semitransparent mirror and a cylindrical lens. The photosensing unit for detecting a shape of the projected image of the light beam is assembled by a first photo-cell having a narrow photoelectric surface extending in the direction of movement of the projected image and second and third photo-cells each having a rectangular photoelectric surface closely disposed to the first photo-cell surface. The second and third photo-cells are connected to a adder to sum signals detected by both cells. The adder and the first photo-cells connected to a differential amplifier to compare the signal detected by the first photo-cell with the output of the adder.

Abstract: A measured stream of particles is dropped onto the apex of a distributor e where it is divided into a circular pattern falling through a narrow sizing zone onto the peripheral edge of a rotatable platen. Platen rotation carries each particle into a frame area viewed, preferably, by a microscope and a TV camera the output of which is applied to a computer programmed to analyze selected characteristics. A rotatably-indexed mirror system reflects selected views into the microscope for the analysis. Interfaced with the computer is a signal generator providing feed-back signals that synchronously control system operation. For example, a feed-back signal stops platen rotation when a particle is brought into the viewing or frame area. Other signals control other functions such as the indexing of the mirror system to provide the desired views, i.e. front, back, top, bottom, etc. Scanning devices other than optics can be used if so desired.

Abstract: A focus detecting device for a lens system having a subsystem for dividing the image of an object into two optically equal images and for shifting the two images of the object in the opposite directions or shifting only one of the two images of the object. Two photoelectric conversion element groups are adapted to convert the variations in relative position of the two images of the object into electrical signals. An optical system projects the images of the object onto the two photoelectric conversion element groups, in which the following outputs are obtained from the outputs of photoelectric conversion elements forming the two photoelectric conversion element groups by using a calculating circuit: ##EQU1## where: n is the number of photoelectric conversion elements forming each photoelectric conversion element group, m is the number in order of a photoelectric conversion element and, i.sub.1 through i.sub.n and i'.sub.1 through i'.sub.

Abstract: The invention relates to an arrangement for measuring the range or speed of an object, in which two optical devices are offset from one another transversely to the direction of the object to produce auxiliary images of such an object, which are photoelectrically analyzed relative to one another. The minimum difference signal indicates the congruency of the two auxiliary images and supplies a criterion for the range of the object. In accordance with the invention, the auxiliary images are analyzed by CTD image sensors, whose read-out signals are supplied to a differential amplifier and are then rectified and integrated. The read-out signals from one sensor are changed, as to their phase state, with respect to the read-out signals from the other sensor, by means of a pivotal movement of the relevant optical device, by means of a delay element which can be adjusted in a stepped manner. The range criterion is obtained from the phase state assigned to the minimum difference signal.

Abstract: This invention discloses a device for extracting the space frequency component of an image formed by an optical system. The device comprises means having a photoelectric element array including a plurality of photoelectric elements on which said image is projected and time-sequentially generating, at a predetermined period, a pulse output having a magnitude corresponding to the intensity of light received by each of the photoelectric elements, means for successively storing the respective pulse outputs, means for converting each of the stored pulse outputs into an AC signal, and means for adding together the AC signals and producing the same.

Abstract: A focus servo apparatus for an optical information reading system is disclosed, which includes an optical system for a light from an information carrying surface of a recording medium composed of a condenser lens, a cylindrical lens and a light receiving element. A subsystem is employed for maintaining light illuminating focussed on the information carrying surface in response to an output of the light receiving element. The distance between the cylindrical lens and the light receiving element is larger than the focus distance of the lenticular lens.

Abstract: This specification discloses an image scanning system in which an object image formed by an optical system is electrically scanned by utilization of a photosensor array device and the image scanning output then obtained is quantized to thereby provide quantized image data. According to the improvement of the present invention, there are obtained two different quantized image data, namely, first quantized image data quantized by a voltage level determined on the basis of the image scanning output from the sensor device and second quantized image data quantized by a predetermined fixed voltage level.

Abstract: An apparatus for measuring a range to a subject comprising a first optical system for forming a first stationary image of the subject on a first photosensitive element such as a photosensor array, a second optical system for forming a second image of the subject on a second photosensitive element, said second image being shifted with respect to the first stationary image by rotating a rotatable scanning mirror of the second optical system, and a pin hole member having first and second pin holes formed therein and arranged in front of the first and second photosensitive elements in such a manner that the pin hole member can be moved in a direction parallel to optical axes of the first and second photosensitive elements as well as in a plane perpendicular to the optical axis so as to change a size and a position of a range measuring area with respect to a field of view.

Abstract: A focus detecting device comprises an image forming optical system, a light beam scanning device for scanning the light beam from the image forming optical system in a predetermined direction and for generating an electrical output corresponding to the scanning direction of the light beam, an image re-forming optical system for re-forming the image formed by the image forming optical system, an image position detecting device for photoelectrically detecting the direction of movement of the image formed by the image re-forming lens, and a discriminating circuit for discriminating between the focusing, the front focus and the backward focus from the direction of movement of the image by the image re-forming optical system with respect to the direction of scanning of the light beam by the scanning optical system on the basis of the outputs of the light beam scanning device and the image position detecting device.

Abstract: A servo unit in an optical information reading device having a lens for focussing an irradiation light beam on the record surface of a disk. A movable mirror positions the focal point of the irradiation light beam formed on the track of the disk. A cylindrical lens is arranged so that the central axis of the cylinder forms a 45.degree. angle with the track direction of the disk to allow a light beam from the record surface to pass through the cylindrical lens. A focussing light receiver having four separate light receiving units is arranged on two orthogonal straight lines. The focussing light receiver receives a focus controlling light beam passed through the cylindrical lens at a distance twice as long as the focal distance of the cylindrical lens.

Abstract: A colorimeter in which a beam dividing assembly is supported on a movable carriage intermediate the sample and reference detectors. The assembly separates the incoming collimated light into a sample beam and a reference beam. The movement of the carriage toward or away from the sample produces a decrease or increase in the intensity of the light illuminating the sample and a corresponding increase or decrease in the intensity of the light at the reference detector. The arrangement is such that the apparatus may be readily adjusted to obtain accurate colorimeter readings even for samples having abnormally high or low density characteristics.

Abstract: An electro-optical position-monitoring system including a tracking detector whose position is interpretable to indicate the spatial location of a monitored object. In one embodiment, the detector includes a beam-splitting prism, and in the other includes two arrays of fiber-optic elements--both arrangements being designed to divide reflected, received light into two optical paths. Interposed in these paths are photodetectors which each produce an output signal directly indicative of the intensity of light received along the associated path. Circuitry which responds to such signals effects tracking movement of the prism (or the arrays) so as to equalize signals produced by the photodetectors. When equalization occurs, tracking stops, and the repositioned location of tracked parts is directly readable as an indication of the spatial location of the monitored object.

Abstract: An apparatus as described for reading an optical radiation-reflecting information carrier, which apparatus comprises an opto-electronic focussing error detection system with two focussing detectors. The path of the read beam which has been reflected by the information carrier and which originates from the read spot includes a single radiation-deflecting element, in such a way that the radiation which is incident on this element is deflected towards the focussing detectors.

Abstract: Pulses of radiation are emitted from the camera to the subject, reflected back to the camera, and incident upon two detectors. The successive pulses produced by the two detectors are applied to respective integrators which trip respective threshold circuits when and if their integral signals reach the threshold value. This inherently reduces detector and other noise present in the processing circuitry. A tolerance-range counter ascertains whether or not, after one threshold circuit is tripped, the other becomes tripped within a predetermined time interval.

Abstract: A tracking servo drawing device in an optical type information reading device utilizes a tracking servo to allow an irradiation light beam to track a record track on an information record surface to read information by using said irradiation light beam illuminating said record surface. A speed detection circuit is used to sense a relative speed of the record track and the irradiation light beam at which the irradiation light beam goes across the video track. When the relative speed is lower than predetermined value, a first detection signal is produced. A signal level detection circuit detects the reproduction signal level of the information. When the level reaches a predetermined value, a second detection signal is produced. When the first and second detection signals are produced simultaneously an instruction signal is generated to close the servo loop of said tracking servo means.

Abstract: A focus detecting device in a single lens reflex camera having a lens system and an optical image splitter for splitting an object image into various partial images disposed at a position optically equivalent to that of a film surface in said single lens reflex camera. An array of photo-electric conversion devices are arranged into at least two rows, each row having a plurality of photo-electric conversion elements. The rows are disposed symmetrically with respect to a center line. The device includes an image projecting device for projecting the partial images onto the photo-electric conversion arrays. The projecting device has an optical axis which optically corresponds to said center line, the output of said conversion array defined by ##EQU1## The output of the conversion array has a maximum value when proper focus is obtained.

Abstract: Focus detecting apparatus for an optical system including first and second image forming optical means for forming the image of an object along first and second spatially separated light paths, first and second photosensitive element arrays each comprising a plurality of photosensitive elements and producing an electrical signal representative of the intensity distribution pattern of the light incident thereon, and circuit means for detecting the focus of the optical system in accordance with the electrical signals from the first and second arrays. The circuit means includes a first processing circuit, a second processing circuit and a phase comparing circuit. The first processing circuit produces an electrical output having a phase representative of the positional relation between the first array and the intensity distribution pattern of the light incident on the first array, in accordance with the electrical signal from the first array.

Abstract: A focus detecting device having a release lens for reforming the image of an object which is formed between a lens and the focal plane of the lens. A mirror is provided between the release lens and an image reforming plane for dividing the primary image into two secondary images. Two light receiving element arrays provided in the image forming planes of said secondary images provide outputs to a signal processing circuit for comparison to produce a signal indicating whether or not the lens is focussed on the object. The mirror for dividing the primary image into two secondary images, shifts the two secondary images in opposite directions on the light receiving element arrays at the time of defocussing so that the difference between the outputs of said two light receiving element arrays is not zero.

Abstract: A method of comparing analog signals delivered from a number of light detecting elements with analog signals delivered from a digital-analog converter by means of a plurality of comparator circuits whose output analog signals are supplied as write enable signals to a plurality of digital memories which are controlled by means of digital signals delivered from a central control circuit such that an illumination intensity information of each picture element is read out as the digital signal in the digital memories, thereby obtaining a signal of detecting a focal point of cameras or the like optical devices.

Abstract: Apparatus for determining the direction a lens should be moved in order to provide a proper focus of a remote object on a predetermine plane. A plurality of radiation detectors are positioned to receive radiation in first and second patterns from the object and to produce signals in accordance therewith. A first plurality of radiation detectors produces signals indicative of the radiation received in the first pattern while a second plurality of radiation detectors produces signals indicative of the radiation received in the second pattern. The two patterns coincide at the proper focus but at other than the proper focus the two patterns are spaced from one another in a direction which depends upon the direction the lens should be moved to achieve proper focus. The low frequency components in the patterns are determined by taking the sums of the outputs of groups of detectors in the first and second plurality of detectors so that individual fluctuations in individual detectors are smoothed.

Abstract: First and second photodetector signals, whose relative amplitudes depend upon focus error, are integrated to form respective first and second integral signals whose relative rates of change are dependent upon focus error. Each integral signal is applied to two comparators, one whose threshold level is reached first and the other having a threshold level which would be reached second. When one or the other of the two integral signals reaches its first-reached threshold level, this applies a corresponding signal to the data input of a respective flip-flop, and when this faster-changing integral signal then reaches its second-reached threshold level this clocks both such flip-flops. The time elapsing between the faster-changing integral signal reaching its first-reached and then its second-reached threshold level constitutes a tolerance interval, during which the slower-changing integral signal is given an opportunity to try to reach its respective first-reached threshold level.

Abstract: A low cost auto focus system employing a bias signal source to cause the system to focus at the infinity or hyperfocal distance when very low contrast conditions exist.

Abstract: Apparatus for determining the direction a lens should be moved in order to provide a proper focus of a remote object on a predetermined plane. A plurality of radiation detectors are positioned to receive radiation in first and second patterns from the object and to produce signals in accordance therewith. A first group of radiation detectors, produces signals indicative of the radiation received on the first pattern while a second group of radiation detectors produces signals indicative of the radiation received, in the second pattern. The two patterns coincide at the proper focus but at other than the proper focus position, the two patterns are spaced from one another in a direction which depends upon the direction the lens should be moved to achieve proper focus.

Abstract: A method and apparatus for determining the direction the taking lens of a camera should be moved in order to provide a proper focus condition. A plurality of radiant energy detectors are positioned to receive energy from a scene being viewed and a first group of such detectors produces a first output signal pattern while a second group of such detectors produces a second output signal pattern. The two patterns coincide at the desired focus position but move with respect to one another in a first or opposite direction depending upon the focus condition. The slope of one or both of the patterns at predetermined positions is multiplied by the difference in value from the outputs of the detectors to create values which are summed. The sign of the summed values is representative of the direction the taking lens must be moved to bring the patterns into coincidence at the desired focus position.

Abstract: A radiation filter for use in a range determining system to reduce the effects of radiation falling on the edges of a radiation detector used in the system to a greater extent than radiation falling on the central portion of the detector.

Abstract: An improved automatic focus system wherein circuitry is provided to inhibit the focusing function when the scene being viewed provides too little contrast for satisfactory operation.

Abstract: An opto-electronic focussing-error detection arrangement is described for the detection of a deviation between a radiation reflecting surface and the plane of focussing of an objective system. In the path of the beam which is reflected by the surface a beam-splitting element is disposed and behind said element two radiation-sensitive detectors are arranged which are each associated with one of the subbeams formed by the beam-splitting element. The detectors are grating-shaped detectors and are effectively divided into two detector sections by selection devices, the bounding line being adjustable. A focussing error signal is obtained which is highly independent of a positional error of the radiation-sensitive detection system relative to the beam axis.

Abstract: A system and method for automatically focusing a camera is disclosed wher the outputs of a conventional spatial image correlator are sensed to develop a distance signal corresponding to object distance. The position of the camera lens is sensed to develop a focus signal indicative of lens position. The ratio of the distance signal to the focus signal is determined and compared to a predetermined value. When that ratio varies from the predetermined value, the lens is automatically re-positioned until correspondence occurs between the predetermined value and the ratio of the focus signal to the distance signal.

Abstract: An automatic focusing apparatus includes a lens for leading a laser beam onto a sample surface at a predetermined incident angle, a beam splitter to divide the reflected beam from the sample surface in accordance with the vertical shift thereof, a pair of photo diodes to respectively receive the divided beams and produce electric signals, a differential amplifier to produce a differential signal between the electric signals and a mechanism to vertically shift the stage by means of the differential signal to automatically focus a lens system on said sample surface.

Abstract: A corrector lens for use in a distance determining system employing a plurality of detector elements arranged in pairs and mounted proximate a plurality of lenslets. Each lenslet creates an image of the exit pupil of the objective lens of the system and when the objective lens is properly positioned, each of the detectors of each pair receives approximately the same amount of radiation. The corrector lens operates to direct radiation from the objective lens to the lenslets so that each lenslet receives radiation generally along its optic axis rather than at an angle thereto so that the radiation detectors may be mounted approximately equal distant on opposite sides of the axis and thus receive radiation from the lenslets along substantially equal paths.

Abstract: A lenslet array for use in a distance determining system. The array utilizes a plurality of cylindrical lenslets arranged in parallel relation with a crossed cylindrical lens arranged transverse to the lenslets and lying in a plane parallel to the plane of the lenslets. The focal lengths of the lens and the lenslets are chosen so that they project an oblong image in a common image plane. Elongated radiation detectors are positioned within the oblong image.

Abstract: A bimodal automatic lens focussing apparatus including detection and switching means for detecting a loss in a localized focal condition and switching to a search mode wherein the objective lens is scanned between its outer limits to reacquire focus. Photodiode arrays sense respective light images on either side of the desired focal plane, and the resulting signals are processed to drive the lens to the desired focal plane. A level discriminator monitors the processed signals. Upon detection of a loss of the localized focus condition a mode switch is gated to couple a ramp generator to the lens driver. The lens is scanned between its outer limits until the level discriminator again detects the localized focus condition and the ramp generator is decoupled from the lens driver.

Abstract: An optical recording apparatus comprises a light source for emitting a light beam, a modulator for modulating the light beam with a signal to be recorded, and an optical system for conducting the light beam thus modulated through a specific light path. The light beam has a specific cross-sectional shape which is projected onto a recording medium. The optical system also includes a restricting plate having a slit or hole for restricting the cross-sectional shape of the modulated light beam to the specific shape. A pair of light detectors are irradiated by the modulated light beam of the restricted cross-sectional shape to detect the intensities of the light beam in the vicinity of two end parts. Any difference between the outputs of the two light detectors control the optical system, in response to the detected difference, so that the light intensity distribution of the modulated beam in the restricted cross-sectional shape is maintained symmetrical with respect to the center of light distribution.

Abstract: An improved automatic continuous focus system of the spatial image correlation type determines whether focus correction is needed and in which direction and moves the lens with a proportional drive in accordance with these determinations. The focus motor may be operated continuously for large focus errors to allow smoother lens motion and faster response without increased motor requirements, a large active scan duty cycle may be provided, minimum drive pulses may be utilized for zero focus errors so as to overcome static friction in the lens drive and improve the focus accuracy and electronic debouncing of switches may be accomplished.

Abstract: An automatic focussing apparatus for microscopes includes a pair of photoelectric transducer elements disposed short of and beyond the imaging position, respectively, of an optical system which is used for the purpose of focussing. Each element is connected with a separate loop comprising an A/D converter which converts an output signal from the associated element corresponding to each picture element into a digital quantity, a sample-and-hold circuit, a calculation circuit which responds to the digital signal to derive an evaluation function, and an accumulator which stores the resulting value. The individual accumulators are connected with a comparison circuit, which is in turn connected with a focus control circuit controlling the optical system.

Abstract: An apparatus for electrooptically focusing the objective in a single lens reflex camera provided with a focusing screen and a split image wedge rangefinder, where focus detectors are used in which an image segment is scanned in an image plane. The focusing window of the focusing screen provided with a split image wedge rangefinder (5) is followed by a pentaprism (8) having a first plane reflecting surface which is partly reflecting. The scanning grating (14) and the photoelectric detector system (17,18) are mounted in the direction of the light beam behind this plane surface of the pentaprism and along the optical axis deflected by one of the wedges (5a) and an optics (11) is present along the optical axis to image the plane of one of the wedges (5a) into that plane where the scanning takes place.

Abstract: An automatic focus adjusting device for use with an optical instrument hag a focusable objective lens which is adjusted by optical and electronic components of the instrument, such components determining the distance of an object by comparing images of separate scanning and reference optical systems. The device of the present invention has a low-reduction filter screen placed across part of each light path of the two optical systems. The filters provide an overriding apparent contrast to low-contrast object fields to cause the system to adopt a pre-set focus distance, but do not interfere with normal automatic focusing where object field contrast is adequate for normal system operation. Manual adjustment of the filter spacing varies the pre-set, low-contrast focus to any desired object distance setting. Five to ten percent light reduction in the screened part of each filter is adequate.

Abstract: A focus detector includes a movable reflecting mirror and a stationary reflecting mirror which reflect incident light admitted through a pair of independent windows for the purpose of comparison. A drive for the movable mirror drives it with different speeds during its movement in a forward and a reverse direction. The comparison takes place when the movable mirror is driven at a lower speed. The drive includes a non-symmetrical eccentric cam, a motor for rotating the eccentric cam, and a support for the movable mirror which bears against the eccentric cam. The eccentric cam is provided integrally with a mode selection cam, which operates to open and close a comparison enable switch.

Abstract: A process and apparatus for the automatic correction of the focusing of a microscope in an image plane utilizes two microscope outputs forming two images of the same object in two different planes surrounding the image plane and two matrices with at least one line of N photodetectors receiving the two images. A contrast measuring circuit of each image is associated with each matrix and a comparator of the signals is used for the two contrast measuring circuits. Connected to the output of the comparator is a circuit for the formation of a correction signal and the microscope is focused by the correction signal.

Abstract: An auto focus system includes first and second detector arrays which receive first and second detection images of an object. The detection images are displaced from each other by a distance which depends upon the distance to a remote object. The detector arrays produce output signals which vary with the position of the detection images and thus with the distance to the object. The output signals are processed to provide a resultant signal indicative of the distance to the object and this signal may be used, for example, to control the position of a lens in a photographic camera.

Abstract: A system for determining the range to an object utilizing a plurality of radiation responsive detectors such as charge coupled devices arranged in groupings where a first grouping of detectors receives radiation from the object primarily through a first portion of a lens and a second grouping of the detectors receives radiation from the object primarily through a second portion of the lens. There is a predetermined relationship between the outputs of the detectors in the first grouping with respect to the detectors in the second grouping when the object is at a predetermined range and changes in the range of the object produce changes in the relationship so as to produce a resultant signal which varies with the range and which may be used for the automatic focussing of photographic or television cameras.

Abstract: A rangefinder mechanism is shown in which the scanning mirror has been replaced with a movable scanning optic. The automatic rangefinder system includes a pair of optical paths, one a reference path and the other a scanned path, which are lead to impinge upon a photosensitive surface for comparison purposes. The output of the photosensitive surface is used to adjust the main lens of the camera. The range of the movable optic is coordinated with the position of the main lens of the camera as feedback and adjustment of the rangefinder.

Abstract: A method and apparatus for automatically focusing a camera is described in which the camera has a stationary optical path and a scanning optical path for developing focusing signals. The scanning optical path is caused to undergo a range-finding reciprocation in which it reciprocates between first and second limit positions, as between the minimum lens focusing position and the infinite lens focusing position. Two focusing signals are generated during the range-finding reciprocation and the interval between the focusing signals is used to derive the distance to the subject. The lens is then positioned in accordance with the derived distance to the subject.

Abstract: First and second optical systems each comprise identical converging lenses which focus light images of an object onto identical photosensor arrays, the lenses being parallel. First and second mirrors reflect the light images from the respective lenses onto the respective arrays. The first mirror is fixed whereas the second mirror is rotatable. Where the second mirror is rotated to a position where the light images on the arrays are identical, the distance to the object is a function of the position of the second mirror which is predetermined by triangulation. As the second mirror is rotated through a predetermined range the arrays are strobed a predetermined number of times to produce analog signals having magnitudes corresponding to incident light. The respective analog signals are subtracted and the resulting difference signals compared with a previously minimum value. Each time the arrays are strobed a counter is incremented.