Ascension Technology Corporation

Don Odell

Alec Duling

An optical system for determining the angular position of a radiating point source is disclosed, wherein radiation from a point source travels through a mask and onto the surface of a sensor. A preferred embodiment employs a plurality of mask transmission frequencies and a detector designed to be sensitive to the phases of the frequencies. A computer measures the phases of a plurality of detected image frequencies. Measurement of the particular phases of the frequency components allows determination of the image shift on the detector axis. The image shift is then used to compute angle of incidence of the light source upon the detector. The preferred embodiment employs a refractive window, hence the angle of incidence between point radiating source and mask are determined using the window index of refraction and refraction equations. Applications include within the cockpit of a jet aircraft.

Optical system for determining the angular position of a radiating point source and method of employing

A sensor for determining the angular position of a radiating point source in two dimensions includes a mask encoded in two skewed directions with waveforms consisting of several frequencies in prescribed patterns. The frequency spectra of the received detector patterns are computed. In order to facilitate such computations, the constituent frequencies are separated so as to be distinguished in the Fast Fourier Transform (FFT). Each of the frequency patterns that are coded on the variable transmissivity mask consists of a series of low frequencies followed by a series of variable frequencies, and a series of high frequencies. The variable frequencies exhibit frequency changes responsive to various image positions. The low and high frequencies are responsive in phase to variations in image position. The frequency variations in the variable frequencies are used to indicate coarse position while the phases of the fixed low and high frequencies are used to indicate medium and fine position. In a second embodiment, the mask pattern is formed by a first pattern including low variable and high frequency components, a second pattern with fixed low and high frequency components, and a third pattern with variable frequency components. The method of determining position is also disclosed.

Sensor for determining the angular position of a radiating point source in two dimensions and method of operation

Embodiments of a device and a technique are disclosed for locating the angular position of a radiating point source with respect to a detector comprising a point source of radiation, a variable transmissivity mask with pseudo-random variations, a multi-element detector and computing means for interpreting the detected image. The mask pattern, when illuminated by a point source of radiation, casts an image on the detector array. Computing means determine the pattern shift to allow determination of point source angular location in two dimensions. The mask transmissivity pattern and corresponding image vary in two dimensions, in such a manner as to yield two correlation peaks that indicate the incident angle in two dimensions. The differential shift and common mode shift in correlation peaks indicate the respective angles of incidence, allowing determination of the angular position of the light source.

Sensor for determining the angular position of a radiating point source in two dimensions

A patterned mask is located at a distance from a linear detector array. A point radiating source illuminates the aperture to cast an image onto the array. A computer is employed to identify frequencies in the frequency domain to determine the image scale and shift along the detector array axis. Determination of the magnification of the aperture image is made employing frequency domain techniques, the aperture pattern being re-scaled to match that of the actual image, so that determination of pattern shift can be made. A first embodiment of the present invention has two variations, one of which employs the use of multiple single frequency components and phase methodology, the second of which uses multiple single frequency components as well as a variable frequency component. In a second embodiment, a composite image is also used except that only one single frequency component is used in addition to a non-periodic function.

Range adaptable system for determining the angular position and distance of a radiating point source and method of employing

In a first embodiment, a single linear array of bi-cell optical detectors is arranged with each bi-cell optical detector having a rectangular aperture located a prescribed distance above the surface of the bi-cell optical detector. In the first embodiment, in calculating the position of a point source emitter, it is understood that each detector receives light from the point source emitter at a unique angle different from the angles at which the other detectors receive light from the point source emitter. A plot of detector ratios is made by taking the best fit line through the ratios from each detector and the location of the point where the detector ratio is zero yields the point of perpendicularity between the emitter and the linear detector array. Another embodiment contemplates a three dimensional detector having three linear arrays of bi-cell detectors arranged at the periphery of a measuring space mutually orthogonal to one another. Calculation of the x, y and z intercepts through calculations of lines of regression or planar intercepts allows one to calculate the x, y and z coordinates of the point source emitter.

Optical position measurement system employing one or more linear detector arrays

Position and orientation determination uses stationary fan beam sources and rotating mirrors to sweep fan beams. In a first embodiment, a single motor has an elongated drive shaft with mirrors mounted on it, the reflective faces of which lie either in common planes or face in opposite directions. Fan beams are generated by stationary laser beam sources aimed at each mirror. As the mirrors rotate, each stationary source is reflected off a particular mirror and into a measuring space in a predictable pattern of movement. Electrical circuitry is provided with knowledge of the rotative position of the mirrors at any given time. A sensor attached to the object to be measured detects time of arrival of impinging scanning beams. At least one of the fan-shaped beams is skewed with respect to other beams, and at least two of the fan-shaped beams have origins sufficiently separated to allow accurate triangulation of the position and orientation of the sensor over various regions of the measuring space. In this way, accurate measurement of position and orientation may be carried out. In a second embodiment, separate drive motors are provided, each of which carries a mirror with the drive shafts of the motors preferably being parallel to one another and with the reflective surfaces of the mirrors lying in either common planes or parallel planes. A method is also disclosed.

Position and orientation determination using stationary fan beam sources and rotating mirrors to sweep fan beams

A system for position and orientation determination of a point in space employs, in a preferred embodiment, three scanning laser beams that rotate at a high rate of speed within a prescribed space. At least two of the beams are polarized and a sensor with two or three detectors is located within the prescribed space. In each embodiment, at least one of the detectors has an unobscured, clear view of all of the scanning light beams at all times and at least another of the sensors is partially obscured. In the preferred embodiments, at least one sensor is polarized as well. Computer means is provided to facilitate calculation of position and orientation of a point within the prescribed space.

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Milton, VT, United States of America

Don Odell