Other

Automated Precision, Inc.

Government of the United States of America, As Represented by the Secretary of Commerce

Ap Robotics, LLC

Cam C. Lau

Kam Chiu Lau

Yuanqun Liu

Yongwoo Park

Guixiu Qiao

Yuan-Qen Liu

Robert J Hocken

Liangyun Xie

Shuai Sun

Guangkun Li

Herbert Lau

Quanhe Ma

A broadband interferometry for a measurement range extension beyond a coherence length of a light source is achieved through a local oscillation of the reference beam is replicated by a cavity multiplication or cascading optical delayed lines with a fiber optic cavity, and quantifiable optical properties including a wavelength group delay, a chromatic dispersion, a polarization mode dispersion and a model dispersion are inserted into the local oscillation of the reference beam to incrementally quantify the replicated copies of the local oscillation as the number of the delayed copies of the local oscillation increase for extension of a measurement rage to the target.

Broadband interferometry and method for measurement range extension by using same

Disclosed herein are interferometric measurement systems and methods. In one exemplary embodiment an interferometric measuring system for measuring the distance to or displacement of an object includes: a light source; an interferometer with a measuring arm and a reference arm; a dispersive medium; and a detector. The interferometer is disposed between the light source and the object. The dispersive medium is arranged to unbalance the dispersion between the measurement arm and the reference arm. The detector is arranged to detect spectrum interference from the interferometer. In one example, the dispersive medium is a chirped fiber Bragg grating. In another example, the dispersive medium is a highly dispersive optical fiber. In one example, the light source is a broadband light source, and the detector includes a spectrometer. In another example, the light source is a wavelength swept laser, and the detector includes a photodetector or a balanced photodetector.

Interferometric distance measurement based on compression of chirped interferogram from cross-chirped interference

A system is provided for gathering information and data on the surface characteristics of an object includes a projector, a table, a first camera and a second camera. The projector is suspended above the table and arranged to project a random pattern of optical indicators onto the table. The optical indicators can be dots, lines, or other such indicators. The table is arranged to hold the object to be inspected. The first camera is positioned above and to one side of the table and angled toward the table. The second camera is positioned above and to opposite side of the table and angled toward the table. The first and second cameras are arranged to capture images of the optical indicators projected onto the object. The system is further arranged to gather information and data from the captured images and determine the surface characteristics of the object from said gathered information and data.

Systems and methods for gathering data and information on surface characteristics of an object

A optical target assembly is disclosed herein. The optical target assembly is movable about orthogonal pitch, yaw and roll axes and includes a reflector, a pitch and yaw angular sensor assembly, and a roll sensor assembly. The reflector is configured to engage a source of laser light. The pitch and yaw angular sensor includes a laser light sensor and an angle detection sensor. The pitch and yaw angular sensor assembly is configured to measure 360 degrees of motion about the pitch and the yaw axes. The roll sensor assembly is configured to measure 360 degrees of motion about the roll axis. The reflector can include an aperture configured to permit a portion of laser light incident on the reflector to pass through the reflector and onto the laser light sensor. The roll sensor assembly can include a roll angle sensor and a roll level sensor coupled to a two-dimensional pendulum.

Multi-dimensional measuring system with measuring instrument having 360&#xb0; angular working range

A multi-dimensional measuring system is disclosed wherein a laser-based tracking unit communicates with an optical target on a measurement instrument to obtain position and orientation information about the instrument. The optical target incorporates a plurality of encoders configured to provide a full 360&#xb0; working range in pitch, yaw and roll. Full working range in pitch and yaw is achieved through the use of a pitch/yaw angular encoder. Full 360&#xb0; working range in roll is achieved with a combination of a level sensor and a 360&#xb0; angular encoder, which are fixed to a pendulum so that the level sensor is always aligned to gravity. Use of a slip-ring mechanism ensures the unlimited full working range in roll. The measurement instrument includes a scanner integrated with a probe receptacle adapted to accept a probe assembly to provide the instrument with both a scanning measurement and a probe measurement capabilities. Incorporation of an additional probe receptacle provides increased measurement capability and flexibility. The optical target with its full 360&#xb0; angular working range in pitch, yaw and roll can be utilized independently of the measurement instrument. In combination with a laser tracker, the optical target can be attached to any object or surface to be measured, or alternatively, it can be attached to a movable device and the position of that device monitored.

A volumetric error compensation measurement system and method are disclosed wherein a laser tracker tracks an active target as the reference point. The active target has an optical retroreflector mounted at the center of two motorized gimbals to provide full 360 degree azimuth rotation of the retroreflector. A position sensitive detector is placed behind an aperture provided at the apex of the retroreflector to detect the relative orientation between the tracker laser beam and the retroreflector by measuring a small portion of the laser beam transmitted through the aperture. The detector's output is used as the feedback for the servo motors to drive the gimbals to maintain the retroreflector facing the tracker laser beam at all times. The gimbals are designed and the position of the retroreflector controlled such that the laser tracker always tracks to a pre-defined single point in the active target, which does not move in space when the gimbals and/or the retroreflector makes pure rotations. Special mechanism and alignment algorithm are used in the gimbal design and retroreflector centering alignment to achieve accurate rotational axis alignment and repeatability.

Volumetric error compensation system with laser tracker and active target

A system for accurate determination of target orientation in a laser tracking system. A target aperture is configured to produce spatially distinct laser beam and background images. A processing unit is configured to determine a centroid of the laser beam image position using information collected from detected images, such as laser beam and background images. The laser beam image centroid position is used to determine an accurate target orientation. In one example, a process for determining target orientation includes the steps of collecting a background image passing through a first retro-reflector at a first laser light sensor; 2) collecting a measurement image passing through a second retro-reflector at a second laser light sensor; 3) establishing a common positional reference point for the measurement image and the background image; 4) subtracting the background image from the measurement image based on the common positional reference point.

Accurate target orientation measuring system

A laser based tracking unit communicates with a target to obtain position information about the target. Specifically, the target is placed at the point to be measured. The pitch, yaw and roll movements of the target, and the spherical coordinates of the target relative to the tracking unit are then obtained. The target can be, for example, an active device incorporated into a moveable device such as a remote controlled robot.

Multi-dimensional measuring system

An optical measurement system increases the number of translational and angular measurements made with a single laser beam by combining an optical interferometer with an optical autocollimator. Translational measurements are made with an optical interferometer and yaw and pitch measurements are made with an autocollimator. In a preferred embodiment, angular deviations in the reflected measuring beam are minimized with a reverse telescopic lens assembly, allowing a wider range of angular measurements without significant degradation of interferometer accuracy.

System and method for three-dimensional measurement

A machine tool is controlled through a process incorporating the steps of (1) measuring geometric and thermal errors with accurate instruments, (2) creating a global differential wet model of machine tool position, and (3) using this model to control real time compensation of machine tool operation. A controller modifies encoder-type position feedback signals used by the machine to compensate for geometric and thermal errors in the manner dictated by the global differential wet model.

Real time machine tool error correction using global differential wet modeling

A 6-axis laser measurement system includes a novel 5-D measurement apparatus and a precision laser roll detector. The 5-D system measures pitch, yaw, X, Y, and Z displacements with a single setup of a laser head and detection housing. The laser roll detector uses a polarizing prism, such as a Glan-Thompson prism, and at least two photodetectors. A linearly polarized laser beam enters the prism, and the beam is split into two polarized components, the intensities of which vary with roll orientation of the detector relative to the polarized laser beam. The outputs of the two photodetectors are connected to the positive and negative inputs, respectively, of a high gain differential amplifier which provides a roll output.

Five-axis/six-axis laser measuring system

A measurement probe has a plurality of movement directions, and is constructed with one or more pneumatically actuated locking mechanisms, each of which can be selectively actuated to prevent movement along one of the movement directions. The pneumatic actuator has a flexible diaphragm which is expanded by application of air pressure to move a spring member, thus engaging a locking element connected to the spring member with a receiving element to prevent movement of the probe in the direction associated with that locking mechanism. A pneumatic control system is provided to control the locking mechanism(s) in accordance with operator desires, a predetermined program, or operating requirements of an electronically controlled machine associated with the probe.

Method and apparatus for selectively locking a movement direction of a

A tracking system for measuring at least the spatial coordinates of a target and possibly the angular orientation of the target. A collimated beam is directed to the target and a mirror attached to the target reflects this beam back to a tracking point. Photosensors attached to the tracking or target point provide error signals to a servo system which controls optics at the tracking or target points to provide the direction necessary to accomplish the coincidence of the beams. An interferometer interferes the source beam with the beam that has travelled twice between the tracking and target points in order to measure the separation. By measuring the directions of the beams relative to structure attached to the tracking and target points, the target point can be located in spatial coordinates and additionally the orientation of the target structure can be determined.

Growing community of inventors

Potomac, MD, United States of America

Kam Chiu Lau