Abstract: An optical scanner for indicia arranged in a focal plane perpendicular to an optical system including a rotatable dove prism. The dove prism transmits a rotating image to a stationary photodiode array.

Abstract: Three-dimensional information and a three-dimensional display of the surface of an object is provided by a scanning laser beam mounted on a high-speed rotating disc to repetitively scan across an object transported below the disc upon a moving carrier. Light reflected from the object surface back along the axis of the scanning beam is detected to indicate surface characteristics, such as reflection intensity. Positions of the projected beam in the course of its scanning rotation and of the carrier in the course of its transport motion are detected to generate signals that define the XY position of the scanning beam. Light of the projected energy beam, as reflected from the object at an angle to the beam axis, is imaged by a second lens upon a linear detector array, whereby the position of the image along the linear detector array will indicate elevation of the reflecting area along the axis of the projected beam.

Abstract: Apparatus is disclosed for producing clock signals which are used to precisely control the modulation of a first light beam as it is line scanned by a moving mirror. The apparatus employs a second beam of light which is reflected from the moving mirror and is intensity modulated by a grating. A paraboloid mirror receives such intensity modulated second beam and reflects a collimated beam. A lens focuses such collimated beam to form a stationary image on the surface of a detector which produces the clock signals.

Abstract: The present invention discloses a photoelectric converting apparatus which comprises a spot-like light beam generating source, an optical system scanning the light beam linearly on a scanned surface, and light receivers having a long piece along the direction of the scanned line and disposed close to the scanned surface in order to receive the reflected light from the scanned surface and generate an electric signal corresponding to the intensity of received light.

Abstract: A hardware packaging assembly for a galvanometer optical beam scanning apparatus includes an optical component-containing portion having a light source aperture through which the output beam from the ILD that carries the to be recorded data passes. This aperture is disposed in a wall defining a boundary of the interior of the housing. Light from the ILD is reflected off a fixed mirror disposed adjacent to an opposite wall and is directed to a galvanometer scanning mirror. As the mirror is rotated about a longitudinal axis, it scans the ILD output beam across an output (image correction) lens mounted in the housing. A second opening disposed in the rear wall of the housing interior receives a start-of-scan photodetector element, which is positioned to detect light that is back-reflected off the inner face of the lens at a prescribed angle of sweep of the beam by the galvanometer mirror.

Abstract: A filter cleaning system for an opacity monitor which has a light source and a light sensor on opposite sides of a first optical path through a gas whose opacity is to be measured, comprises a mechanism for calibrating the opacity monitor during a calibration period and a purging air arrangement for supplying purging air to pipes in the first optical path to keep the interior of the pipes clean. A primary filter is connected to the blower for filtering the purging air. Three-way valves are connected to the input and the output of the blower so that a secondary filter can be utilized to supply clean air in a reverse flow through the primary filter to clean the primary filter. The primary filter is cleaned during this blow-down period at the same time that calibration is taking place for the opacity monitor. In this way, no measuring time is wasted and still the life of the primary filter is extended.

Abstract: Method and apparatus for forming a pattern in which an array duty factor of elementary pattern marks which are elements for forming a picture is no less than 0.5.

Abstract: A free floating mount for the holographic disc of a scanner which enables centrifugal force developed by rotation of the disc to bring the disc into perpendicular relationship with the axis of the disc motor shaft and prevent disc wobble, comprising, a first self aligning couple composed of a pin and socket for supporting the disc on the end of the motor shaft, the shaft and disc having coaxial bores therethrough; a tensioning cable assembly extending through the motor shaft and disc bores, one cable segment of the cable assembly being attached to a retaining ball receivable in a socket in the disc, the retaining ball and socket forming a second self aligning coupling; a second cable segment at the opposite end of the cable assembly having a retaining ball attached thereto receivable in a socket in the motor shaft end and forming a third self aligning coupling; an extension spring interconnecting the first and second cable segments to form the cable assembly whereby the motor shaft and disc are biased through

Abstract: An apparatus and method are disclosed which monitor the position of a scanner platform and, in response to roll of the platform, compensate a scanner device mounted thereon to maintain the center lines of the angles of scan in alignment as defined by a line parallel to the direction of movement of the scanner platform relative to the object which is scanned.

Abstract: In an apparatus for recording an image by scanning a recording material with a light beam or a heat beam through rotation of a rotating body having at least one light source or heat source, the output of the light or heat source is controlled to obtain a sharp image free of scanning nonuniformity. A non-recording period on the recording material is detected by use of a combination of a light projector and a light receiver positioned in the rotating body with a light reflector secured near the rotating body, or a combination of a light receiver positioned in the rotating body with a light projector secured near the rotating body, or a combination of a magnetic sensor positioned in the rotating body with a magnet secured near the rotating body. The output of the light or heat source is stabilized by a stabilizing circuit within the detected non-recording period.

Abstract: An optical scanner for orthogonal scanning in read and/or write modes has a framing mirror (20) for linear vertical scanning and a rotating disc (30) with a circular array of concave reflectors (32) for horizontal scanning. Primary imagers (24, 164) focus the linear vertical scan onto a strip mirror (26) which reflects the scanned pixels to the concave reflectors. Preferably, the concave reflectors reflect the pixel image in a collimated beam which is focused by a collection optic (38, 200) onto radiation detector (40). Image rotator (221), collection aperture defining device (270, 272), aperture shading device (290), and a device for suppressing spurious radiation are also provided.

Abstract: In an optical scanning system suitable for use in an aircraft for ground contour measurements, wherein the received image from an illuminated ground spot is reflected from a rotating prism onto paraboloidal mirrors which focus the image at a common focal point, and wherein the rotating prism is also used to transmit the scanning spot-illuminating beam, a wedge-shaped light guide accepts the coincident focused images and funnels them into a photoelectric detector. Because the prism rotates at high speed, variations in light signal transit times due to differences in target distance over the range of the scan cycle and due to differences in aircraft altitude cause the image focal point to shift, necessitating a relatively wide rectangular input aperture on the light guide, resulting in the admittance of large amounts of background light in to the detector.

Abstract: An optical scanning device, for scanning bundles of parallel rays of light defining a field of view, includes a substantially planar disc, means for rotating the disc on its axis, and a substantially planar reflective member. The disc has a first portion which is reflective and a second portion which is transmissive. The planar reflective member is arranged in a fixed position behind the disc such that the normal to the planar reflective member subtends a nonzero angle with respect to the disc axis. As the disc is rotated, the light rays to be scanned are alternately incident upon the reflective portion of the disc and the transmissive portion of the disc. When the light rays are incident on the transmissive portion, they pass through the disc and are reflected by the fixed reflective member which is arranged behind the disc. Both the reflective portion of the disc and the fixed reflective member reflect the light rays to be scanned onto a fixed detector.

Abstract: A scanning system for optical scanning of a scene in at least one dimension has a multi-faceted reflective scanning rotor as the scanning element. In order to have a high scanning efficiency a so-called facet-tracing is provided such that the beam path is reflected by first and second areas of reflection on the rotor, both areas being disposed in a non-collimated beam path. An optical beam converging means is disposed in the beam path between the scene and the rotor for forming a primary image of the scene between the beam converging means and the rotor. A substantially spherical mirror is disposed in the beam path of the system between the first and the second areas of reflection. A radiation detector is disposed at the end of the beam path. A beam converging optical element, such as a positive lens or a substantially spherical mirror, is disposed in the beam path between the first substantially spherical mirror and the second area of reflection.

Abstract: A range imaging system in which a periodic pattern is projected onto the scene to be imaged. Three frames of intensity values are collected as the pattern shifts 120.degree.. The phase by which variations in range cause portions of the pattern to shift are determined from the three frames of data as being proportional to range. To generate the phase information, the intensity value for each pixel in the third frame is subtracted from intensity values of the same pixel of the first and second frames. The arc tangent of a function of these difference values represents the phase shift, and thus range.

Abstract: An apparatus for automatically adjusting the characteristic of a deflection unit, illustratively of the type used in laser recording equipment. A reference value for the deflection unit is conducted to a first input of a multiplier, the second input of which is connected to the output of a first memory. The output of the multiplier is connected to a first input of an adder, the second input of which is connected to the output of a second memory. In addition, a comparator is provided which compares the position of the deflection unit with two adjustment reference values. The content of the second memory is varied in response to a zero-adjustment command until, for a predetermined reference value zero, the deflection unit has assumed a zero position. Upon the issuance of a slope-adjustment command, the content of the first memory is varied until, for a second adjustment reference value, the deflection unit has assumed its desired position.

Abstract: A range imaging system in which a moving periodic pattern is projected onto the scene to be imaged. The phase by which variations in range cause portions of the pattern to shift are monitored to develop range data. A television camera offset from the axis of illumination generates four frames of intensity values. The moving pattern shifts one-quarter cycle with respect to the pattern between each of the frames. The data from the third frame is subtracted from the first frame and the data from the fourth frame is subtracted from the data of the second frame to cancel the effects of background illumination. The first difference represents a sine signal and the second difference represents a cosine signal. The arc tangent of the quotient of these values represents the phase, and thus the relative range of various points in the image. The moving pattern can be generated by either a translating plate or rotating disk which has a periodic variation in transmissiveness.

Abstract: The surface of a part to be identified or inspected is scanned by a laser beam projected normal to the surface to be scanned from the end of a rotating arm in a circular scan pattern. A small collector lens is fixed to the end of the rotating arm and has a hole through which the projected beam passes. The part moves across the scan pattern in a direction perpendicular to the projected beam, and intensity of reflected light received by the lens and transmitted to a detector provides precision information concerning surface characteristics, orientation and discontinuities.

Abstract: An optical scanning system includes scanning means arranged to scan an object field and comprising, in one form, a rotatable drum (10) carrying a plurality of pairs of mirrors (12, 13). A detector (21) is provided which is sensitive to optical radiation directed on to it by the scanning means. Means, such as telescopes (17, 22) collect radiation from at least two fields of view for presentation to the object field of the scanning means. Optical switching means are provided so that radiation reaches the detector (21) from each field of view in turn. The switching means may be an optical shutter (14) having reflective regions (15) and transparent regions (16).

Abstract: The laser beam of a flying spot scanner is turned on and off to write data under control of a reference clock that generates clock signals determined by the position of the writing beam. To detect position of the writing beam a reference beam is scanned in synchronism with the writing beam along and through a coding mask to a strip of retroreflective material fixed adjacent the mask. The reference beam is retroreflected through the mask back through the scanning optics to a fixed detector that produces an output determined by the scanning coded reference beam. Unwanted reflections from the mask surface are separated by tilting the mask.

Abstract: A system is disclosed for transforming a collimated beam of light, such as that generated by a laser, into a beam of light which repetitively scans a fixed path by utilizing a mirror which is repetitively rotated through a predetermined angular displacement. The angle between the mirror axis of rotation and the mirror position relative to the axis varies between subsequent mirror rotations and defines a scanning beam rotational axis error which is eliminated by the present invention. An input beam of collimated light is directed onto the rotating mirror along a first path to produce a first scanned reflected output beam for each rotation of the mirror. A second scanned reflected output beam is generated by redirecting the first scanned reflected output beam through a prism and back onto the mirror along a second path. The second path is vertically displaced from the first path by a distance related to the mirror rotational axis error.

Abstract: In a radiant energy beam scanning system, a detector, positioned at a predetermined position along the path scanned by the beam, for sensing the center position of the power distribution within the beam and generating a signal indicative thereof. When utilized in an information recording system, the detector is positioned adjacent the start position of the scan path so that the generated indicator signal provides a reference for system timing and synchronization. In such a recording environment, synchronization of the system relative to the center position of power distribution within the beam compensates for variations in beam power level and focus, assuring proper alignment of information recorded on consecutive scan lines. In a preferred form, a diode detector, partially masked in a cross-scan direction, is employed to provide an output signal when irradiated by the scanning beam.

Abstract: A light beam scanning device in which scanning speed irregularities of a light spot in a scanning plane are corrected using a signal which is generated in response to light passing through a grid pattern. First and second light beams are directed onto a scanning mirror, which may be an oscillating mirror or a rotary multi-surface mirror. The deflected first light beam is scanned on a recording surface while the deflected second light beam is directed through a grid pattern. An optical detector produces an output signal in response to light passing through the grid pattern which is used to control the movement of the beam deflecting device. Preferably, the grid pattern is curved to lie along a circle having the deflection point of the second light beam on the surface of the mirror as its center.

Abstract: An optical scanning apparatus embodied in a gyroscopic missile seeker to provide a rosette scan pattern of the field of view. A single driving motor is employed with a traction drive assembly to produce the necessary counter-rotation of scanned elements and thereby effect the rosette scan pattern.

Abstract: A scanning method for scanning a scanned surface simultaneously by a plurality of beam spots in which each beam spot passing through light beam detecting means provided outside the requisite scanned area of the scanned surface, to detect the time when each beam spot begins the scanning of the requisite scanned area, is focused with respect to the scanning direction of the beam spot and defocused with respect to a direction orthogonal to the scanning direction.

Abstract: Data recorded in non-parallel arcuate paths on a data carrier are read with a laser beam which rotates relative to the data record.

Abstract: An optical scanning apparatus embodied in a gyroscopic missile seeker to provide a rosette scan pattern of the field of view. A single driving motor is employed with a traction drive assembly to produce the necessary counter-rotation of slightly canted scanning elements and thereby effect the rosette scan pattern. A canted primary focusing mirror is directly driven by the motor and is connected through a traction drive to a canted secondary mirror to effect proportional counter-rotation of the secondary mirror.

Abstract: A method and apparatus for image acquisition utilizing a non-planar beam of electro-magnetic radiation, such as, a hollow conical beam of light, to illuminate at least a portion of an object. The conical beam of light is generated by impinging a light beam on the surface of a concave, cylindrical reflector. The light beam enters the concave cylindrical reflector through the hollow shaft of a motor. The illuminated portion of the object is imaged on an array of photosensitive elements to produce corresponding signals that are representative of the image on the array. These signals can be used to obtain identification information concerning the object and guidance information for a plural axis manipulator employed in conjunction with the object. In one application the image acquisition apparatus is used in a robot to provide control signals for guiding the robot tool along a path, such as, a welding seam.

Abstract: Apparatus for scanning a laser beam including a beam splitter for splitting a laser beam into a scale scanning beam and a read/write scanning beam, a modulator for applying information to the read/write scanning beam, lenses and mirrors, including a cylindrical lens for directing both beams onto the same facet of a rotating polygonal scanning mirror, and a lens for focusing the modulated beam to a spot on a scanned medium and for focusing the unmodulated beam through a scale onto a detector for providing timing pulses for the apparatus.

Abstract: A scanning system providing a linear scanning beam utilizing a fiber optic bundle, one end of which forms a circle which is scanned by a light beam and the other of which forms a straight line. Other fibers are within and external to the circle formed by the one end of the fiber optic bundle and are used to provide a feedback signal used to correct the scanning light beam to impinge only on the fiber ends of the one end of the bundle.

Abstract: A method and apparatus for image acquisition utilizing a non-planar beam of electro-magnetic radiation, such as, a hollow conical beam of light, to illuminate at least a portion of an object. The conical beam of light is generated by impinging a light beam on the surface of a concave, cylindrical reflector. The illuminated portion of the object is imaged on an array of photosensitive elements to produce corresponding signals that are representative of the image on the array. These signals can be used to obtain identification information concerning the object and guidance information for a plural axis manipulator employed in conjunction with the object. In one application the image acquisition apparatus is used in a robot to provide control signals for guiding the robot tool along a path, such as, a welding seam.

Abstract: An optical slip ring provides optical communication between a pair of members free to rotate with respect to each other. These members may be a pair of optical fibers, an electrical conductor and an optical fiber or a pair of electrical conductors. One member is attached to a first mounting device and the other member is attached to a second mounting device. One optical receiver is positioned in the center of the first mounting device on a common axis of rotation with respect to the second mounting device. The other optical receiver is mounted on the second mounting device, positioned on the common axis of rotation. One optical emitter is mounted off center on the first mounting device and the other optical emitter is mounted off center on the second mounting device.

Abstract: An electro-optical light scanning system using a modulated laser illumination source directed upon a multifaceted rotating polygonal mirror or polygon. The mirrored facets reflect the impinging light toward a moving photoreceptor and forms a raster of scan lines as the photoreceptor moves. The system incorporates sensing optics and closed loop electronics for correcting inaccuracies in the position of the reflected light resulting from defects in the angular relationship between the plane of the facets and that of the rotating axis of the polygon as well as those errors due to inherent angular misalignment between each of the facets of the rotating polygon. The invention also encompasses amplitude modulation for varying the intensity of the laser illumination in conjunction with the acousto-optical modulation for maintaining a constant level illumination and/or for varying the spot size.

Abstract: An opacity monitor (10) including a light source (12) mounted on one side of a duct (14), and a detector (16) mounted on the opposite side of the duct is disclosed. The light source (12) and the detector (16) are rotated by motor means (26, 36), respectively, between a first position aligned with each other along an open light path defined across the duct (14) and a second position aligned with each other on opposite sides of a calibration tube (18) extending across the duct (14). Shutters (28, 38) rotate with the light source (12) and the detector (16), respectively, and are aligned with the calibration tube (18) when the light source (12) and the detector (16) are aligned with the open light path, and vice versa.

Abstract: An optical scanner for indicia arranged in a focal plane at a cylindrical outside surface by use of an optical system including a rotatable dove prism. The dove prism transmits a rotating image of an encircled cylindrical surface area to a stationary photodiode array.

Abstract: Correction for variations in scan period of optical image scanners includes measuring and storing the scan times at which optical events occur to cause image detector signals, detecting an optical marker near the end of the scan and the scan time of its detection, determining the difference between this scan time and a stored scan period, comprising the nominal scan time for marker detection, which difference represents the scan period error, dividing the difference by the stored scan period to provide a scan time unit error and multiplying each stored measured scan time by the unit error to provide a correction for each measured scan time, thereafter adding the correction to the stored measured scan time to give a corrected scan time.

Abstract: In order to effect recording on a recording medium by projecting a beam on the recording medium, the beam must be deflected at a predetermined velocity. To deflect the beam at a predetermined velocity, the present invention detects the deflected beams by a beam detector to form a velocity signal and compares the velocity signal with a reference signal to control the motor of the deflector by the comparison output.

Abstract: A thermal imaging system generating high resolution images at commercial T.V. rates while scanning relatively large apertures comprising a facet mirror mounted for rotation about a rotational axis, a framing mirror mounted on axis for oscillation about an oscillatory axis, and an off axis, magnifying relay lens system for reimaging the pupil at the facet mirror onto the framing mirror so that there is a real pupil at the framing mirror with no image artifacts. The relay lens system is located in the optical path between the facet mirror and the framing mirror. The relay lens system defines an image plane and at least one point blackbody is located substantially at the image plane for purposes of providing a video reference and calibration. A detector receives the focused beam of radiation reflected by the facet mirror for subsequent display on commercial T.V. monitors. The detector shares vacuum with the high-speed scanner.

Abstract: A family of two axis horizon sensors using the same basic scan technique is provided which achieves a relatively wide altitude range with a minimum of moving parts for performing vehicle attitude control and guidance. The horizon sensor for indicating the orientation of a space vehicle senses a line of discontinuity in optical radiation between a reference planet and outer space in at least two planes using a single sensor which includes a single detector means for detecting the optical radiation. The detector is scanned across the line of discontinuity in at least two planes. The scanner includes a rotary element driven by a single motor having at least two stationary reflecting elements positioned therearound. A phase reference signal generator is coupled to the motor and driven in synchronism therewith for generating at least two reference signals at predetermined points in the scan.

Abstract: A scanning system combining active and passive detection of radiation from targets. In the active mode, a laser beam is scanned with a rotating wedge in a downward looking Palmer pattern, a portion of the beam is reflected from targets, and coherent detection is performed on the returned signals. Means is disclosed for automatically compensating for misalignment between the signal return beam and local reference beam upon the coherent detector. In the passive mode, infrared radiation inherently emitted by targets is also detected.

Abstract: A telemetric optical-radiation laser transmitter 5 outside an aperture 2 sends a beam to a point 14 scanned over the charge surface 1, via a rotating assembly 7 of deflectors, one deflector 11 oscillating with a periodicity related to the rotation of the assembly. A telemetric receiver 19, sensitive to the radiation from the transmitter 5 in a selected wavelength range, receives radiation re-transmitted from the point 14 through an aperture 3. A thermometric receiver 6 receives thermal radiation from the point 14 along a path coinciding with the path of the transmitted optical radiation.

Abstract: A scanning laser doppler system in which the change in angle between transmitted and received beams caused by the finite transit time to the target is automatically compensated. The scanning beam is produced as a downward looking Palmer scan pattern by an expanded laser beam transmitted through a rotating wedge. The rotating wedge is tilted in accordance with the invention to align the received beam with a portion of the transmitted beam upon a detector.

Abstract: An electro-optical light scanning system using a modulated laser illumination source directed upon a multifaceted rotating polygonal mirror or polygon. The mirrored facets reflect the impinging light toward a moving photoreceptor and forms a raster of scan lines as the photoreceptor moves. The system incorporates sensing optics and closed loop electronics for correcting inaccuracies in the position of the reflected light resulting from defects in the angular relationship between the plane of the facets and that of the rotating axis of the polygon as well as those errors due to inherent angular misalignment between each of the facets of the rotating polygon. The invention also encompasses speed control as well as amplitude modulation for varying the intensity of the laser illumination in conjunction with the acousto-optical modulation for maintaining a constant level illumination and/or for varying the spot size.

Abstract: An optical information storage system having a data record with control markings therein and an optical readout system including a scanner. The readout system uses a laser light source and focusing optics to direct the light onto the data record for modulation and subsequent readout of the modulated light. Shutter elements are interposed to intercept the transmission of light in response to control signals in the data. The shutter, of the electronic type such as lead lanthanum zirconate titanate, may be positioned either between the source of light and the scanner or between the data record and the readout.

Abstract: An aerial vehicle rotating in gyroscopic fashion about one of its axes having an optical system operative to scan an area below the vehicle in determined relation to vehicle rotation. A sensing device is provided to sense the physical condition of the area of scan and optical means are associated therewith to direct the physical intelligence received from the scan area to the sensing means. Means are provided to incrementally move the optical means through a series of steps to effect sequential line scan of the area being viewed keyed to the rotational rate of the vehicle.

Abstract: A banknote condition monitoring apparatus features a mirror wheel (22) located substantially at the focus of a concave mirror strip (25) with an intervening plane mirror (26) to fold the beam path. The mirror wheel (22) scans an incident light beam from a source (28) to form a transmitted light beam in the image space of the concave mirror (25) which is continuously displaced parallel to itself to and fro through the image space. The transmitted light beam is directed via a cylindrical lens (14) onto the surface of a drum (11) carrying the banknotes (12) to be monitored on its peripheral surface by way of air suction via the channels (32). Light remitted from the surface of the banknote is directed through the lower half of the cylindrical lens (14), impinges on a light conducting rod (15) and is detected at an and face of the light conducting rod by a light receiving device (33).

Abstract: A circular scan reader utilizes oscillating mirrors and associated optics to generate a circular scan pattern of laser light focused to a small spot. The angle of the scan emanating from a point just inside the reader through a window forms a conical shape which permits scanning inside a yarn tube without inserting any portion of the reader into the tube. When the scan passes over a bar coded label, the changes in reflection of light between the bars and spaces are detected by a photodetector mounted on the face of the window. These fluctuations in light which correspond in width to the bar and space width are converted to an electrical signal that is amplified, and decoded. A driver circuit for the oscillating mirrors controls the scan rate and scan pattern. The scan rate is modulated to cause a variation in the sweep depth in the tube thus providing an area scan. The area scan reduces the need for accurate label placement in the tube core.

Abstract: An improved method for finding the refractive properties of lenses includes placement of the test lens in an optical system such that its image lies in a plane at which light passes through at least two spaced areas. The beams passing through those areas fall on respectively associated targets. The amount and angle of separation and the positions of the points of impingement of the beams are used to find the magnitude of spherical lens power component and magnitude, and angle of any prismatic and cylindrical power components. That information can be found by computation or by the use of means for displacing the targets and light source until the beams strike reference points on the targets. The amount of target or source displacement is then a function of the magnitude of the several optical powers and the orientation of the prismatic and cylindrical powers.An apparatus for practicing the method is described. It accomplishes target and source displacement with servo-mechanisms.

Abstract: An alignment apparatus for bringing two objects, each having at least one reference mark, into a predetermined positional relation is disclosed in which the two objects are scanned by a beam of light emitted from a coherent light source, the light coming from the reference marks is received and converted into electrical signals by means of which the amount of deviation between the two objects is detected and the two objects are adjusted to the predetermined positional relation. Repetitively swept light from the light source is divided into two parts which scan the reference marks at different times and along different directions.

Abstract: An improved circular scan line tracing device for use in connection with flame or plasma cutting machines, as well as other machine tools, is disclosed which features provision for adjustment of the lead of the tracing device while the machine is operating.