Abstract: An active etalon comprising a laser gain chip interposed between an input mirror and an etalon end mirror is provided. In an intracavity frequency-doubled solid-state laser, a pump source emits pump radiation which passes through the input mirror and into the laser gain chip. The laser gain chip lases in response to the pump radiation to produce fundamental laser light. The etalon end mirror reflects a portion of the fundamental laser light back into the laser gain chip and transmits the remaining portion of the fundamental laser light into the laser cavity. The input mirror reflects substantially all of the fundamental laser light into the laser gain chip. The portion of the fundamental laser light which passes through the etalon end mirror may be frequency doubled by a frequency doubler chip and a portion thereof transmitted through the front end of the laser cavity to form the output laser beam.

Abstract: A pipe alignment system and method is provided for positioning a pipe line along a predetermined path. A light transmitter generates a reference light beam along which the pipe line is to be positioned. The light beam has wavelengths substantially in the green portion of the optical spectrum. An optical target is positioned at one end of each pipe section to assist in alignment thereof. Preferably, the optical target has a green tint which filters the green light from ambient light. The optical target may also have reference indicia thereon to assist in aligning the target with the reference beam of light.

Abstract: A solid-state laser comprises a pump diode for generating pump radiation and transmitting the pump radiation into a laser cavity. The pump radiation passes through an entrance mirror and enters a laser gain chip which lases to produce fundamental laser light. The fundamental laser light passes through a harmonic reflector and a first dispersive element and is frequency doubled by a frequency doubler chip to produce harmonic laser light. The harmonic laser light passes through a second dispersive element and impinges on a mirrored surface. A portion of the harmonic laser light passes through the mirrored surface to form the output beam of the laser. The remaining portion of the harmonic laser light is reflected back into the laser cavity. First and second dispersive elements control the phase of the harmonic laser light in the laser cavity such that substantially all of the harmonic laser light is in-phase when the harmonic laser light impinges upon the mirrored surface.

Abstract: A solid-state laser for generating harmonic laser light substantially at a desired wavelength has a pump diode body made of a first material, which is preferably aluminum, having a first coefficient of expansion and a laser diode mounted in the pump diode body for generating pump energy. A laser body assembly, which is positioned on the pump diode body, is made of a second material, which is preferably steel, having a second coefficient of expansion. The first and second coefficients of expansion of the respective pump diode body and the laser body assembly have a known relationship such that the laser cavity expands and contracts at a particular rate as the temperature of the laser increases and decreases to provide a substantially constant generation of the harmonic laser light. A laser gain chip mounted on an entrance mirror, which forms the back end of a laser cavity, generates fundamental laser light in response to pump energy from the laser diode.

Abstract: A pipe alignment device and method is provided for efficiently generating an air flow in sections of pipe such that the sections of pipe may be aligned along a prepositioned reference laser beam without refraction errors. A fan blade assembly is supported in one end of the pipe section by a support frame. A motor, mounted on the frame, rotates the fan blade assembly through a plurality of intermeshed gears to generate a air flow in the pipe. The fan blade assembly defines a light transparent aperture which permits the reference laser beam to enter the pipe sections concomitantly with the generated air flow. The light transparent aperture may include a window disposed therein.

Abstract: An intracavity frequency-doubled solid-state laser uses a Nd:GdVO.sub.4 laser gain chip to generate a beam of visible laser light which may have wavelengths substantially in the green portion of the optical spectrum. A back end of the laser cavity is defined by an entrance mirror while a front end of the laser cavity is defined by a mirrored surface. A laser diode generates pump light which is transmitted through the entrance mirror into the laser gain chip. The laser gain chip, which may be immediately adjacent the entrance mirror, emits fundamental laser light having a wavelength of approximately 1063 nm in response to the pump light. A frequency doubler chip positioned immediately adjacent the laser gain chip doubles the frequency of the fundamental laser light to produce harmonic laser light having a wavelength of substantially 532 nm.

Abstract: An earthmoving apparatus and method for grading a tract of land to a desired finish contour wherein a continuously updated contour map is displayed to the operator of the earthmoving apparatus during the grading process is provided. The earthmoving apparatus has a blade of known width for cutting and filling soil of the tract of land. Vertical blade movement and the x and y position of the earthmoving apparatus is continually detected by respective sensors as the earthmoving apparatus traverses the tract of land. An ultrasonic transmitter and receiver detects elevation of the soil, preferably located behind the blade, to provide updated soil elevation information. A computer then uses the aforesaid information to generate a visual representation of a contour map of the tract of land with cut and fill lines thereon.

Abstract: An assembly for use in a laser instrument which produces a plane of laser light by reflection from a cone. The assembly includes a weak focusing lens which improves the control over the planarity of the plane of light produced. Because it is weak, the weak focusing lens can be positioned over a relatively large distance to produce slight changes in the focus of the beam which is reflected to produce the plane of light. Critical, time consuming, and expensive manufacturing requirements can be relaxed, while improved performance results in superior laser instruments.

Abstract: An aircraft control system for applying chemicals to an agricultural field in one of a plurality of flight patterns is provided. A global positioning system receiver receives radio frequency signals from satellites and the position of the aircraft is determined from the information contained in the received signals. An aircraft computer stores the surface coordinates of the field to be sprayed. The aircraft pilot enters the desired orientation, swath width and track width of the flight pattern into the computer. Based on the aforementioned information, the computer produces a flight pattern having the desired orientation and generates, via a pilot headset, audible signals representative of amount and direction of deviation from the desired flight pattern. The computer means may also automatically activate and deactivate chemical spraying upon entering and exiting, respectfully, the airspace above the field.

Abstract: A method and system for determining the position of at least one position retroreflective element in a predetermined frame of reference using two benchmark positions of known coordinates. A light transmitting and detecting means and a reference retroreflective element are oppositely positioned at a primary benchmark position located at known first coordinates and a secondary benchmark position located at known second coordinates. The light transmitting and detecting means takes angular measurements by sensing a reflected light beam from the position and reference retroreflective elements. After taking angular measurements in the above configuration, the light transmitting and detecting means and the reference retroreflective element are transposed and additional angular measurements are taken. From the angular measurements, the position of the position retroreflective element is determined in the coordinate frame of reference.

Abstract: An automatic plumb, level, pointing and distance measuring tool uses a visible laser diode to project a beam in any of several different modes through a beam exit window. The tool, approximately the size and shape of a tape measure, can be placed on one edge to project a tilt-compensated vertical beam. Placed on another edge 90.degree.-rotated, the tool projects through the same exit window a tilt-compensated horizontal beam. When laid on either of its larger flat sides, the tilt compensation becomes inoperative and the tool projects a beam which is fixed relative to the housing. Acoustic distance measurement is facilitated using a second component or target side device which receives both a light beam an acoustic signal simultaneously projected from the laser tool across a space to be measured. A receiver in the target side device first detects arrival of a characteristically modulated or pulsed light beam, received at a photodetector on the target side device, and then receives the acoustic signal.

Abstract: An assembly for use in a laser instrument which produces a plane of laser light by reflection from a cone. The assembly includes a weak focusing lens which improves the control over the planarity of the plane of light produced. Because it is weak, the weak focusing lens can be positioned over a relatively large distance to produce slight changes in the focus of the beam which is reflected to produce the plane of light. Critical, time consuming, and expensive manufacturing requirements can be relaxed, while improved performance results in superior laser instruments.

Abstract: A laser alignment apparatus is provided for use in positioning workpieces relative to one another and first and second spaced-apart substantially parallel reference planes. The laser alignment apparatus comprises a first projector for providing first and second reference beams of light disposed in a substantially orthogonal relationship with respect to one another. A second projector provides third and fourth reference beams of light disposed in a substantially orthogonal relationship with respect to one another. The first and second projectors are positioned relative to one another so that the first and third reference beams of light are substantially collinear with one another and the second and fourth reference beams of light are positioned substantially parallel to one another.

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

Abstract: An automatic plumb, level, pointing and distance measuring tool uses a visible laser diode to project a beam in any of several different modes through a beam exit window. The tool, approximately the size and shape of a tape measure, can be placed on one edge to project a tilt-compensated vertical beam. Placed on another edge 90.degree.-rotated, the tool projects through the same exit window a tilt-compensated horizontal beam. When laid on either of its larger flat sides, the tilt compensation becomes inoperative and the tool projects a beam which is fixed relative to the housing. Acoustic distance measurement is facilitated using a second component or target side device which is activated to send an acoustic signal across a space to be measured, toward the laser tool. A receiver in the laser tool detects arrival of the acoustic signal and causes the laser to project a characteristically modulated or pulsed beam, received at a photodetector on the target side device.

Abstract: A light beam deflecting apparatus is provided for diverting a light beam from an initial path. The apparatus includes first and second substantially transparent plates. The light beam passes through the first and second plates when the first and second plates are positioned in the path of the beam of light. A connector is attached to the first and second plates for connecting the plates to one another and for permitting the plates to be displaced relative to one another. A bellows enclosure is attached to the outer edges of the first and second plates for encasing the first and second plates to form a reservoir therewith capable of supporting a fluid therein. A fluid is filled within the reservoir and causes the light beam to deviate from its initial path when the first and second plates are located in the path of the light beam and are positioned in a non-parallel position.

Abstract: A laser beam projector apparatus is provided and includes a laser tube for producing a primary light beam in an initial path. A first beam diverter is included for diverting a first portion of the primary beam into a first direction to emerge from the apparatus as a first reference beam and for diverting a second portion of the primary beam into a second direction substantially parallel but opposite to the first direction. The apparatus further includes a second beam diverter for intercepting the second portion of the primary beam and allowing a first part of the second portion to pass therethrough and emerge from the apparatus in the second direction as a second stationary reference beam. The second beam diverter further serves to divert a second part of the second portion substantially 90 degrees into a third direction.

Abstract: A load-referenced, pressure reducing valve, and a system which incorporates one or more of such valves provide needed response to rapidly changing hydraulic system load demands which are experienced with automatic control systems. The valve provides rapid response for pressure regulation by providing the load pressure to one side of the valve so that immediate, load referenced valve adjustment occurs instantly upon change of load conditions at a system load, and pressure regulation begins immediately without need for fluid flow.

Abstract: A method and apparatus are disclosed for controlling the cross slope angle cut by the blade of an articulated frame motorgrader being steered through a turn, operated in a straight frame mode, in a crabbed steering position and/or traveling in a non-horizontal plane. The blade angle is sensed and controlled such that the sensed blade angle is maintained substantially equal to a calculated blade angle. In a first embodiment, the blade angle calculation is performed using the equation: tan BS=(sin .tau.')(tan R)+(cos .tau.')(tan CS) where BS is the required blade slope angle of said blade relative to horizontal; .tau.' is a rotational angle of the blade with respect to the blade's direction of travel projected into horizontal; R is an angle between the blade's direction of travel and horizontal; and CS is the desired cross slope angle which is entered by an operator of the motorgrader. In a further embodiment, the blade angle calculation is performed using the equation: tan BS=(sin .tau.")(tan R')+(cos .tau.

Abstract: A laser beam target for use with a projector capable of providing a reference laser beam of light traveling in a predetermined path is provided and includes a main body portion having first and second surfaces. A plurality of projections are provided on at least one of the first and second surfaces for directing at least a portion of the reference beam of light into a specific range of vertical viewing angles away from the path of the beam as the light passes from the body, thereby permitting a worker viewing the target to more easily determine when the reference beam of light is in alignment with appropriate reference indicia on the target.