Abstract: A method and apparatus for capturing an image of at least one object appearing in a field of view (FOV). A housing has an image sensor and a base lens assembly fixedly mounted relative thereto. A moveable lens assembly is movably mounted relative to the housing. The moveable lens, the base lens assembly, and the image sensor are aligned such that light received within the FOV passes through the moveable lens and the base lens assembly and impinges onto the image sensor. The light received from the FOV forms an original image prior to entering the movable lens and the base assembly. Light from the FOV impinging onto the sensor forms an impinging image.

Abstract: Some embodiments of the invention include a coordinate measuring device, in particular a laser tracker, for capturing the position and alignment of a measuring aid, which is movable in space and comprises a retroreflector. In some embodiments, the coordinate measuring device may include at least a support fastened on a base so it is rotatable about a first axis of rotation; a beam deflection unit fastened on the support so it is rotatable about a second axis of rotation, which is essentially orthogonal to the first axis of rotation, a first bearing for the rotatable mounting of the beam deflection unit on the support, and a second bearing for the rotatable mounting of the support on the base.

Abstract: Disclosed is a stereo endoscope system comprising stereo endoscopes of varying working lengths, working diameters and directions of view. Each stereo endoscope comprises two identical optical systems where every pair of corresponding components is permanently couple in a sideways orientation. The system is capable of withstanding harsh conditions associated with medical equipment cleaning and sterilization, particularly, the high temperatures and pressures associated with autoclaving. Each of the corresponding components of the two identical optical systems is paired and moved relative to each other to adjust focus and then affixed to create a new singular optical component. The system includes a prism block that extends the distance between the optical axes on the stereo endoscope to the position of two video chips.

Abstract: An optical system for imaging an object has at least a first objective, at least a first image stabilizing unit and at least a first eyepiece, wherein, as seen in the direction of the first eyepiece from the first objective, the first objective is arranged first along a first optical axis, then followed by the first image stabilizing unit and then followed by the first eyepiece. The first image stabilizing unit is rotatably mounted in cardan-joint fashion about a first hinge point, and the first hinge point is arranged between the first objective and the first eyepiece. The optical system is distinguished by virtue of the fact that the first image stabilizing unit comprises a first lens unit and at least a further optical element, wherein the first lens unit and the optical element are arranged such that the first lens unit is, together with the optical element, rotatably mounted in cardan-joint fashion about the first hinge point.

Abstract: An optical gyroscope is provided for measuring a small angular difference. The gyroscope includes a laser, a pre-selection polarizer, a first beam splitter, a coil of optical fiber, a second beam splitter, a post-selection polarizer, a spectrometer and an analyzer. The laser emits a pulse beam of coherent photons. The beam has pulse duration ?. The pre-selection polarizer pre-selects the photons, and the first beam splitter separates the photons by their horizontal |? and vertical |? polarization eigenstates. These beams are launched into a fiber optical coil of radius r, which preserves polarization. The coil rotates by a difference rotation angle ??. The second beam splitter recombines the polarized photon beams as they exit the coil. The post-selection polarizer post-selects the photons. The spectrometer captures the post-selected photons and measures the associated frequency translation ??.

Abstract: A laser stabilization system includes laser source having first and second ends; first waveguide portion having first and second ends, first end of first waveguide portion coupled to first end of laser source; second waveguide portion having first and second ends, first end of second waveguide portion coupled to second end of laser source; micro-cavity coupled between second end of first waveguide portion and second end of second waveguide portion, micro-cavity having resonant frequency; and electronic locking loop coupled between micro-cavity and laser source, wherein electronic locking loop electronically locks laser source to resonant frequency of micro-cavity; wherein first waveguide portion is optical locking loop coupled between micro-cavity and laser source, wherein optical locking loop optically locks laser source to resonant frequency of micro-cavity; micro-cavity stabilization loop coupled with micro-cavity, wherein micro-cavity stabilization loop stabilizes resonant frequency of micro-cavity to ref

Abstract: The present invention includes an illuminance adjustment step of setting an optimum illuminance of the illumination; and a defect inspection step of picking up the image of the substrate illuminated with the illumination at the optimum illuminance, wherein the illuminance adjustment step has: a first step of applying illuminations at different illuminances to a plurality of measurement regions on a front surface of the substrate and picking up an image of each of the measurement regions, while moving the substrate; a second step of making a luminance of the picked up image of each of the measurement regions into a histogram to find a reference luminance where an integral value from a maximum luminance side of the histogram is a predetermined value; and a third step of calculating a correlation between each of the reference luminances and the illuminance, and setting based on the correlation an illuminance at which the reference luminance coincides with a predetermined luminance, as the optimum illuminance.

Abstract: A light-emitting apparatus, for enabling a beam of light to be projected on a desired target located a distance away to project the beam on the desired target without any or substantially any undesired movement. The apparatus may include a housing, a light generating device located within the housing and operable to generate a beam of light, a sensing device or devices for sensing an undesired action of the housing, a control circuit operable to provide a control signal corresponding to the sensed undesired action, and a drive device operable to counter act all or at least some of the undesired action of said housing in accordance with said control signal. The sensing device or devices may be one or more gyroscopes, accelerometers or other such devices.

Abstract: A light-emitting apparatus, for enabling a beam of light to be projected on a desired target located a distance away to project the beam on the desired target without any or substantially any undesired movement. The apparatus may include a housing, a light generating device located within the housing and operable to generate a beam of light, a sensing device or devices for sensing an undesired action of the housing, a control circuit operable to provide a control signal corresponding to the sensed undesired action, and a drive device operable to counter act all or at least some of the undesired action of said housing in accordance with said control signal. The sensing device or devices may be one or more gyroscopes, accelerometers or other such devices.

Abstract: A ring laser gyroscope includes a first plasma shunt arranged to prevent the plasma from contacting a first mirror in the gain region and a second plasma shunt arranged to prevent the plasma from contacting a second mirror in the gain region. The first and second plasma shunts may comprise electrical conductors located in the respective mirror wells and arranged such that contact between the plasma and the electrical conductors quenches the plasma in the mirror wells and produces electrical currents that travels across the mirror wells. The electrical conductors may be formed as metallized strips arranged to extend across the mirror wells, or they may be formed from metal wires. The plasma shunts may alternatively comprise diversion passages formed in the frame and arranged such that the plasma fills the diversion passages and bypasses the mirrors.

Abstract: A light-emitting apparatus, for enabling a spot of light to be projected on a desired target located a distance away such that the spot is projectable on the desired target without any or substantially any undesired movement. The apparatus may include a housing, a light generating device located within the housing and operable to generate a beam of light, a sensing device or devices for sensing an undesired action of the housing, a control circuit operable to provide a control signal corresponding to the sensed undesired action, and a drive device operable to counter act all or at least some of the undesired action of said housing in accordance with said control signal. The sensing device or devices may be one or more gyroscopes, accelerometers or other such devices.

Abstract: A capacitor charging semiconductor apparatus including a plurality of serially connected capacitors to be charged. A direct current source is applied to the plurality of capacitors. A plurality of bypass transistors is provided to bypass charge current supplied to the plurality of capacitors when a voltage of a capacitor exceeds a prescribed reference level. A plurality of parallel monitor circuits is provided to control the plurality of bypass transistors to equally charge the plurality of capacitors. A plurality of capacitor connection terminals is connected to both ends and intersections of the plurality of capacitors. A plurality of transistor connection terminals is connected to the plurality of control terminals of the bypass transistor. A prescribed number of capacitors is optionally charged by increasingly shorting a number of capacitor connection terminals from the highest and lower voltage side capacitor connection terminals.

Abstract: An arrangement for the vertical orientation of a geodetic instrument over a ground point, comprises an optical observation device for visual sighting of the ground point with a target beam, a laser device for generating a laser beam, and an optical in-coupling element by which the laser beam and the target beam can be coupled into a target axis impinging vertically on the target point. In this way, an exact orientation of the geodetic instrument can be achieved under all light conditions. The geodetic instrument retains its compact dimensions. In addition, a laser in a lower hazard class can be used.

Abstract: A multiple axis laser emitter (1) comprising an optical beam splitter (4) having at least two reflectively coated mirror surfaces (7a, 7b, 7c, 7d) oriented perpendicular to each other and each oriented at an angle of 45° to a collimated main beam (H) of a laser light source (6) and at an angle of 90° to each other, wherein, in the beam path, an optical wedge (8a, 8b, 8c, 8d, 8e) is arranged downstream to at least one of the component beams (Ta, Tb, Tc, Td) deflected by the mirror surfaces (7) at an angle of 90° to the main beam (H).

Abstract: A measuring device (6) subjected to gravitational forces and including at least one laterally oscillating, pendulously suspended, support structure (7) for supporting at least one of a measuring element, and optical element, and a suspension element for suspending the support structure and including at least one hinge formed as a tape hinge (21; 40).

Abstract: A portable gravity-based self-levelling device for projecting a laser ray or a flat beam of laser rays (L, L11, L12, L110, L120) in a horizontal and/or vertical direction even if the device lies in an inclined position, comprises: a case (C) in the form of a hollow housing (1); a pendulum (11) suspended inside the case (C) by suspension means (5, 9); means (23A, 23B, 24) for damping the pendulum swing; means (18, 19) for adjusting the equilibrium position of the pendulum (11); and, mounted on the pendulum (11), means (12) for projecting collimated visible laser rays. The suspension means comprise at least one first mechanical decoupling member such as a ball or roller bearing (5), associated with the hollow housing (1), and, lying in a plane perpendicular to that of the first member (5), a second mechanical decoupling member rigidly secured to the movable part (6) of said first member and supporting the pendulum (11).

Abstract: A laser levelling instrument with a levelling base (7) and fine self-levelling of the laser beam (10) has an inner cylinder (5) which bears aligning elements and is suspended in an oscillating manner inside an outer cylinder (1). The laser levelling instrument is characterized in that the outer cylinder (1) and the inner cylinder (5) form a capacitor system with opposite electrode faces; the outer cylinder (1) is joined at right angles to the base (7) and is centred with respect to the beam axis (11); and signals for detecting the oscillating position of the inner cylinder (5) may be derived from the capacitor system.

Abstract: The invention concerns a method of mutually aligning bodies, in particular for the parallel alignment of shafts, rollers and the like, which can be carried out economically and simply in a substantially shorter time than the known methods used for this purpose. The essence of the invention is the use of an optical gyroscope, for example a fiber-optic gyroscope (5), in a position-measuring sensor (4) which is placed in turn in a specific position on the bodies (1, 2, 3) to be mutually aligned for a given time interval to measure the relative angular position. The position-measuring sensor (4) supplies angle data on the basis of which it can be established whether, and if necessary which, position corrections have to be made at the bodies in order to bring them into the desired state of alignment. The invention further concerns a position-measuring sensor which can be used in the method according to the invention.

Abstract: The present invention provides an optical axis compensator, which comprises a liquid sealing container 1 with a transparent liquid 14 sealed therein so as to form a free liquid surface 2, an optical axis compensating unit 44 for allowing a light beam to pass through the liquid sealing container at a predetermined angle and for performing optical axis compensation based on changes of an exit optical axis according to angular change of said free liquid surface with respect to an incident optical axis, a tilting mechanism 12 for tilting said optical axis compensating unit, tilt detecting means for detecting tilt of said optical axis compensating unit, and a control unit for driving said tilting mechanism according to a signal from said tilt detecting means and for leveling said optical axis compensating unit, whereby said control unit drives said tilting mechanism according to tilt detection from the tilt detecting means and levels the optical axis compensating unit, and the optical axis compensating unit compen

Abstract: A two axis optical FLIR gimbal assembly for azimuth and elevation supporting an assembly of optical elements including five folding mirrors, one of which is a Mangin mirror, and six lenses which implement a wide stabilized field of regard and provide a magnification of the incident image. The gimbal assembly, moreover, includes a yoke structure which is driven about an azimuth axis and supports a stable body member which is independently driven about an elevation axis. An independently driven turret is also rotatable about the azimuth axis and shields the gimbal assembly from external forces such as an air stream passing over the fuselage of an aircraft.

Abstract: A plumb laser beam generator includes an internal self-leveling feature to assure the projection of a substantially plumb beam despite tilt of the instrument's housing. Tilt compensation is achieved in preferred embodiments using the angular deflection of a spring due to gravity along with the compensating angular magnification of a telescope which moves pendulously by support on the spring. A laser diode of the instrument is mounted fixedly in the housing, and the telescope resides above the diode and collimating optics, the telescope either hanging by a spring or supported at its base by a spring. The pendulous telescope preferably is motion-damped and includes motion limiting and shock absorbing devices to prevent damage due to sudden acceleration or dropping.

Abstract: A system preferably in the form of an accessory module corrects for tilt angles of a distance measuring laser projecting instrument. The housing of the module includes a compensating mirror mounted on a pendulum which bends with tilt angle by one-half the amount of the housing tilt, so as to reflect the outgoing beam to truly horizontal. In a preferred embodiment a fixed mirror is also included so that the distance measuring instrument can be laid or held approximately horizontally so that its generally horizontal beam is first reflected by the fixed mirror up to the pendulous compensating mirror. The distance measuring instrument preferably has an internal correction to subtract the additional optical path length induced by the use of the accessory module. This may be activated by a switch on the module or automatically when the module is attached to the distance measuring instrument.

Abstract: A beam projecting apparatus has a light source and a reflecting device for reflecting and rotating a bundle of light emitted from the light source for forming a reference plane. A shape converting optical system is provided in an optical path from the light source to the reflecting device for converting the bundle of light from an elliptical sectional shape to a circular sectional shape.

Abstract: The invention provides a passive hand held target for use with a scanning light beam, particularly a laser beam, in which the beam impinged upon (i.e. input to) the target is divided and the resultant beams are directed to a viewing screen witha diffusing function, where an observer can discern equality or inequalities of their images as the target is moved to center its input window with respect to the scanning beam. Adjustment of the target then provides a reference for marking of a surface adjacent the target. The beam divider may include a mask which produces a pair of symmetrical easy to compare beam shapes. An alternative beam divider is an axicon. Holograms can be used as equivalent optical devices for the lens and axicon beam dividing function and for the diffusing viewing function, as well as to direct the beams at convenient angles.

Abstract: An automatic plumb, level and pointing tool uses a visible laser diode to project light beams in two modes through two windows. In the first mode of operation, the unit is able to project a plumb-up beam and a level beam of light while resting on a surface which is as much as 5.degree. out of level. In the second mode of operation the unit is able to project two orthogonal beams or light both approximately in the horizontal plane for aligning one or more reference lines. Accurate, low cost methods of generating level and plumb beams and planes of light are disclosed. One method uses an approximately or partially leveled platform combined with a refractive correction as a second stage.

Abstract: Efficient and cost-effective generation of two co-linear laser beams or two or more intersecting beams, for the purpose of alignment as in the construction industry, takes advantage of the unequal divergence of light from a typical laser diode that produces a beam of elliptical cross section. Two roughly equal co-linear beams of light, or two or more intersecting beams, can be generated by reflecting the collimated elliptical beam from preferably two mirror surfaces oriented obliquely to the beam and so as to divide the elliptical beam in two. If one of the reflective surfaces is a beam splitter, three essentially intersecting beams can be generated. In preferred embodiments these three beams are at right angles to each other, particularly for use in construction layout.

Abstract: This invention provides a laser beam transmitting apparatus which can make the levelling work unnecessary to thereby mitigate the burden of an operator and improve work efficiency. The apparatus is provided with a base, a beam transmitter for supplying a beam of light, a housing, for holding the beam transmitter, and a levelling mechanism provided between the housing and the base, the housing being oscillatably supported on the base, and the center of oscillatory movement thereof lying above the centroid of the housing. Thus, there is achieved double bearing combined with a precise levelling mechanism, provided between the beam transmitter and the housing.

Abstract: A self-leveling plumb, level and pointing tool uses a visible laser diode to project light beams in two modes through two windows. Accurate, low cost structures for generating level and plumb beams and planes of light are disclosed. In principal embodiments, all leveling is accomplished using a very flexible coil spring as a pendulum element, a chain link connection in combination with such a spring, or a point contact suspension. Several accessories are disclosed for use with the laser tool. One accessory is a beam deviation accessory which can be used with the self-leveling laser tool to project a beam of known inclination. The accessory uses a pair of lenses whose relative positions are shifted to generate the desired angle.

Abstract: A self-leveling plumb, level and pointing tool uses a visible laser diode to project light beams in two modes through two windows. Accurate, low cost structures for generating level and plumb beams and planes of light are disclosed. In principal embodiments, all leveling is accomplished using a very flexible coil spring as a pendulum element, a chain link connection in combination with such a spring, or a point contact suspension. Several accessories are disclosed for use with the laser tool, as well as other embodiments.

Abstract: An automatic plumb, level and pointing tool uses a visible laser diode to project light beams in two modes through two windows. In the first mode of operation, the unit is able to project a plumb-up beam and a level beam of light while resting on a surface which is as much as five degrees out of level. In the second mode of operation the unit is able to project two orthogonal beams of light both approximately in the horizontal plane for aligning one or more reference lines. An accurate, low cost method of generating level and plumb beams and planes of light is disclosed. One method uses an approximately leveled platform combined with a weak optical correction. The approximate leveling is done using a single wire or coil spring pendulum element which allows the platform to level itself to within a small fraction of true level, and remaining correction is provided by a weak negative lens or a weak reverse telescope.

Abstract: A gyroscopic system and method is provided for translating parallel and non-parallel lines between a reference line and a device to be aligned with respect to the reference line. A first inertial sensor is provided that is configured to be substantially stationary. This inertial sensor is boresighted with respect to the reference line and includes at least two gyroscopes and a mirror having first and second nonplanar surfaces. A second, portable inertial sensor is provided that includes a gimbal, a gimbal drive system, an electronic energy beam generator, a collimator, and at least two gyroscopes. One or more of the electronic beam generator, collimator, and gyroscopes can optionally be mounted on a platform that is mounted on the gimbal and adapted to move in accordance with signals from the gimbal drive system. A control circuit is provided that is operable to measure output signals generated by the first and second inertial sensor gyroscopes and to determine relative orientations of the inertial sensors.

Abstract: In the case of a fiber optic gyro having a 4.times.4-coupler, the two arms of the coupler which are not connected with the fiber coil are each connected with a monitoring detector. From the output signals of these monitoring detectors, in the case of a desired wavelength, a reference or desired quotient is formed. During the operation of the fiber optic gyro, an actual quotient is in each case formed from these output signals and is compared with the stored desired quotient. The wavelength of a semiconductor laser is controlled by controlling the operating current and/or the temperature of the light source (L) such that the two quotients are identical. The measuring signals will then be error free.

Abstract: A mount for use by optical elements in a laser tooling alignment system. The mount provides a high degree of isolation from external rotational disturbances about any horizontal axis (i.e., pitch and roll) by retaining optical components in a fixed relationship to the local gravity gradient. The mount is a passive gravity referencing two stage, fluid damped pendulum. When a constant deviation optic (e.g. pentaprism beam splitter) is attached to the mount, effective isolation from yaw disturbances is also achieved.

Abstract: A non-magnetic apparatus is disclosed for finding the deflection of the vertical. That apparatus has a device for finding an instrument spatial angle between a reference direction and an instrument characterization direction, and a device for finding a deflection spatial angle between the instrument characterization direction and a direction along a plumb line. Preferably, the device for finding the instrument spatial angle uses a system of gyroscopes. Preferably, the device for finding the deflection spatial angle uses a pendulum.

Abstract: An equipment for measuring difference in elevation employing a leveling pole and a level is disclosed. The leveling pole comprises divisions of coded marks each indicating height at a unit interval. The level comprises a telescope and an image sensor. The output signal of the sensor is decoded for display of digital height value. A plate glass is provided in front of an object lens for vertical compensation of an optical axis of the telescope. An inclination angle of the plate glass required for compensation is used for interpolation between two adjacent coded marks.

Abstract: A pendulous compensator for use in a light beam projector including a light beam source comprises first and second upper pulleys spaced from one another and secured to the light beam projector. First and second lower pulleys are positioned beneath the first and second upper pulleys and supported by filament strands, tapes, loops or the like extending around the upper and lower pulleys. A pendulum mirror is secured to and supported between the first and second lower pulleys for receiving a light beam from the light beam source and reflecting the light beam in a desired angular orientation relative to horizontal. The first and second lower pulleys in the pendulum mirror are supported such that the pendulum mirror is moved to compensate for tilting of the light beam projector. The first and second upper pulleys or a folding mirror may be controlled to select a grade angle relative to horizontal of a projected light beam.

Abstract: A transducer is employed for measuring angles of inclination, angles of up to about 180.degree. and rectilinear positional changes according to a new electrooptical principle based on the fact that the flows of radiation emitted by two sources of radiation and measurable by means of a radiation-sensitive element are dependent on the angular position of a screen element. The primary function of the transducer is to perform accurate measurements of angular positions. To this end, the invention is conceived so as to eliminate or reduce the influence of all significant sources of error on the measuring result. This is achieved by using special radiation-sensitive elements for sensing and correcting operational changes and through the system design. For optimal utilization of the transducer, it further comprises a microprocessor from which the measuring result is obtained as a high-resolution digital signal.

Abstract: Motion damping apparatus is provided for use in a light beam projector including a light beam and a pendulous compensator adapted to movably support a mirror for deflecting the light beam to compensate for tilting of the projector. The apparatus comprises at least one motion damping plate formed of an electrically conducting material and coupled to the pendulous compensator. Magnets are positioned adjacent the damping plate for generating a magnetic field through which the plate passes as the result of motion of the pendulous compensator such that the motion is damped by the interaction of magnetic fields produced by the magnets and by eddy currents generated in the plate by its movement within a magnetic field. The motion damping plate preferably is curvilinear and coupled to the pendulous compensator to move in substantial conformity with a corresponding curvilinear plane defined by the movement of the pendulous compensator.

Abstract: The sensor comprises a radiation source (2), optical elements (5), a pattern generator (4), and a sensor field (3) which includes a plurality of distinguishable, measurable points. The pattern generator (4) changes the beam reflected from an object (8), imaging a pattern on the sensor field (3). An evaluator means (6) samples the individual distinguishable, measurable points of the sensor field and determines the measurement variable on that basis.

Abstract: A system for monitoring changes in shape of a structure employs a laser source attached to the structure and a set of beam splitters mounted at various locations on the structure and arranged to route portions of a laser beam produced by the laser source into various video cameras also mounted on the structure. Each video camera includes a photodetector array and produces an output signal indicating the intensity of light detected by each photodetector of the array, thereby indicating the beam intensity distribution in a corresponding plane of interest. The video output signal of each camera is digitized and stored as an intensity data array in the memory of a digital computer. The computer calculates from the intensity data array the position of the centroid of the beam with respect to a reference point on the plane of interest using a least squares fit of the intensity data to a two-dimensional Gaussian intensity distribution.

Abstract: A light source, such as a laser diode, is positioned on a mount bed facing upwardly. A lens device is supported a support member extending upwardly from the mount bed. The lens device consists of a concave lens and convex lens and is provided to convert the rays of light emitted by the light source to parallel rays of light perpendicular to a true horizontal plane. The concave lens is suspended above the light source by plural wires from the support member. The convex lens is supported above the concave lens by at least one arm attached to the support member. A motorized rotatable reflector device is mounted on the support member above the lens device and reflects the parallel rays of light therefrom in a horizontal direction.

Abstract: A laser surveying equipment includes a laser beam luminous section, a suspending reflection member suspended in such a manner as to reflect laser beam radiated from the laser beam luminous section upward and always to direct the optical axis of such reflected light in the perpendicular direction, and a projection lens system adapted to project the laser beam after forming it into a generally parallel flux of light. A rotary reflection member can be rotatably arranged in order to displace by approximately 90 degree an optical path of parallel flux of light obtained from the projection lens system and to scan the parallel flux of light toward a surveying object within a horizontal plane.

Abstract: A multiple pane lighthouse assembly in a reference laser beam projecting apparatus includes a plurality of transparent panes disposed in an arrangement that defines a transparent window structure which permits transmission of laser light therethrough and has a generally polygonal cross-sectional shape. The window structure has spaced corners formed by pairs of adjacent ones of the opposite side edge portions of the panes. The side edge portions of the panes in each pair are offset relative to one another in forming a respective corner. The offset position of the side edge portions of each pair in forming a respective corner exposes only an interior edge on one of the adjacent side edge portions to laser light being transmitted through the window structure. The path of laser light through the adjacent side edge portions forming the corner is thereby affected only by one interior edge on the respective one of the adjacent side edge portions of the panels at each corner.

Abstract: A transmitter for an alignment system in which a field of electromagnetic radiation is propagated in a non-planar reference cone is disclosed. The transmitter includes a chassis with a source fixed to the chassis for providing a beam of electromagnetic radiation and an optical deflector which converges toward the source reflects the beam into an omni-directional cone of radiation. A flexible support having an omni-directional stiffness supports the optical deflector in the beam to reflect the reference field in a level orientation when the chassis is level. An angular error in the orientation of the chassis from level results in the optical deflector deviating from the aligned position to maintain the reference field in the level orientation. Damping of the deflector is also provided for and sensors detect when the angular error of the chassis has exceeded an allowable amount.

Abstract: A surveying instrument and procedure are provided for the precise determination of elevation differences in the course of a surveying traverse. The instrument comprises an optical wedge 13 situated on the horizontal longitudinal line of sight axis 27 of the primary optical system between the objective lens 11 and a target under observation. The wedge is arranged for rotation about this axis and with such rotation angularly displaces the diverted line of sight 28 from the horizontal to the plane of the target. The degree of rotation required of the wedge to acquire the target 33 is measured by electro-optical angle encoder means 10, and the distance to the target by EDM means 24, 26. The difference in elevation is calculated trigonometrically by computer means utilizing as data the wedge diversion angle, the sine function of its rotation, the computed angular displacement of the line of sight, and the distance to the target.

Abstract: A fiber-optic rotation sensor comprises a coil of polarization-holding, single-mode optical fiber (25) having a core (26) with a non-circular cross-section defining two transverse orthogonal axes, the outer surface (28) of said fiber having a non-circular cross-section with a predetermined geometric relationship to said orthogonal transverse axes, a laser source (30) coupled to one end of said fiber (25) for supplying said fiber (25) with an optical signal having a fixed polarization plane, said non-circular outer surface of said fiber (25) forming a reference surface (29) for precisely aligning one of said transverse orthogonal axes of said fiber core (26) with said fixed polarization plane of the optical signal from said laser source (30).

Abstract: A transmitter for an alignment system in which a field of electromagnetic radiation is propagated in a non-planar reference cone is disclosed. The transmitter includes a source for providing a collimated beam of electromagnetic radiation directed parallel to a beam axis. A cantilever strand supports a bob within the beam. The bob has a conical reflecting surface to reflect the collimated beam conically. Optimally, the cantilever strand and bob are chosen to provide a deflection between the bob and plumb which is substantially one-half of any angular error between the beam axis and plumb. In an especially preferred form, a housing surrounds the bob and has inner and outer surfaces which minimize temperature effects on the orientation of the reference plane. Also, detectors are provided to sense when the angular error between the beam axis and plumb is outside of an acceptable range.

Abstract: The encoder comprises a pendulum (P) mounted to rotate about a horizontal is (O-O) which is substantially coaxial with a reference axis (R-R) of an index disk and which carries vertical optical detector equipment (T.sub.M.pi.E, T.sub.M.pi.R, T.sub.MOE, T.sub.MOR), optical guidance means (M.sub.1, M.sub.2, M.sub.3, M.sub.4, T.sub.5) fixed to the pendulum and suitable for guiding radiation generated by an optical transmitter (T.sub.M.pi.E) towards an associated optical receiver (T.sub.M.pi.R) along a predetermined optical path intersecting the disk (D), and a liquid level forming device (L) fixed to the pendulum (P) and inserted on the optical path upstream from the said point of interception between the optical path and the disk, the said optical guidance means (M.sub.1, M.sub.2, M.sub.3, M.sub.4, M.sub.

Abstract: The present invention provides a two-axis optical inertial reference system wherein the rotor (12) of a gyro (10) is utilized as a stable reference. A surface (19) of the rotor is made reflective. Sighting on the reference is provided through a window (18) in the gyro case, (16) to access rotor reflective surface (19) the gyro case being hard mounted to a moving surface in the coarse gimbal of the system, since the gyro rotor has a finite angle of travel with respect to the case. A stabilized inertial platform (gyro rotor (12)) is achieved without the need of intermediate servoed gimbals. The gyro torquers are used to precess the rotor's spin axis to provide a means for slewing the spin axis and, hence, the optical system's line-of-sight (60) to the desired direction of the optical system. Specific embodiments for obtaining the required reference beam are disclosed.

Abstract: The telescope of the level-transit includes two mirrors at 45.degree. to the light path. A first mirror is fixed in the telescope housing by screws which thread into the mirror support to pull it tight against a datum surface established by a cover. The other mirror is mounted for pendulating action to automatically compensate the instrument for deviation from level within the design range. When the instrument is used as a transit the telescope is free to tilt up and down to measure vertical angles. At that time the pendulum is locked in center position. When the instrument is used as a level, the telescope is locked against elevation or depression. The locking mechanism actuates a device which frees the pendulum for operation to automatically compensate the level. The bottom of the pendulum weight has an inverted conical member fixed therein. The conical portion passes through an elongated hole in a leaf spring fixed in the telescope to flex about an axis transverse the mirror pivot axis.