Method and system for high-speed, high-resolution, 3-D imaging of an object at a vision station
First Claim
1. A method for the high-speed, high-resolution, 3-D imaging of an object at a vision station to develop dimensional information associated with the object, the method including the steps of:
- scanning a beam of controlled light in a scanning direction at the surface of the object at a first predetermined angle to generate a corresponding reflected light signal;
receiving said reflected light signal at a second angle with a set of optical components for creating a relatively small focused spot of light from the reflected light signal, the set of optical components including first and second lenses;
filtering the received light signal with the set of optical components;
measuring the amount of radiant energy in the reflected light signal with a small area position detector having a detector area and having a position-sensing direction substantially orthogonal to the scanning direction and producing at least one electrical signal proportional to the measurement; and
computing a centroid value for the reflected light signal from the at least one electrical signal;
wherein the improvement comprises;
converting the focused spot of light into an enlarged, elongated spot of light and imaging the filtered light signal to the small area position detector with an anamorphic magnification and field lens system, including a third lens for magnifying the focused spot of light in the position-sensing direction of the position detector and a fourth lens having a relatively short focal length for reducing the focused spot of light in the scanning direction to form the elongated spot of light, wherein the position detector comprises a single detector element including the detector area of less than 20 mm2 and having a relatively small capacitance and dark current and wherein the entire elongated spot of light is uniformly imaged to a discrete extended region of the detector area, to obtain a relatively high signal to noise ratio, the extended region being elongated in a scan dimension substantially orthogonal to the position-sensing direction, wherein spatial noise resulting from variations in sensitivity from point to point in the detector area are averaged.
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Abstract
A method and system for high-speed, high-resolution, 3-D imaging of an object including an anamorphic magnification and field lens system to deliver the light reflected from the object to a small area position detector having a position-sensing direction. Preferably, an acousto-optic deflector together with associated lens elements scans a beam of modulated laser light across the object to produce a telecentric, flat field scan. The deflector has a feedback loop to enable uniform illumination of the object. The light scattered from the object is collected by a telecentric receiver lens. A combined spatial and polarization filtering plane preferably in the form of a programmable mask is provided to control the polarization and acceptance angles of the collected light. A reduction or focusing lens is positioned immediately behind the filtering plane and is utilized as a telescope objective. The lens system includes a negative cylinder lens having a relatively large focal length and a field lens having a relatively small focal length. The cylinder lens and the reduction lens magnify the image in the position sensing direction of the detector and the field lens delivers the magnified light to the detector. The detector is a photodetector such as a lateral effect photodiode or a rectangular lateral effect detector. A pre-amplifier provides a pair of electrical signals which are utilized by signal processing circuitry to compute the centroid of the light spot.
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Citations
21 Claims
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1. A method for the high-speed, high-resolution, 3-D imaging of an object at a vision station to develop dimensional information associated with the object, the method including the steps of:
- scanning a beam of controlled light in a scanning direction at the surface of the object at a first predetermined angle to generate a corresponding reflected light signal;
receiving said reflected light signal at a second angle with a set of optical components for creating a relatively small focused spot of light from the reflected light signal, the set of optical components including first and second lenses;
filtering the received light signal with the set of optical components;
measuring the amount of radiant energy in the reflected light signal with a small area position detector having a detector area and having a position-sensing direction substantially orthogonal to the scanning direction and producing at least one electrical signal proportional to the measurement; and
computing a centroid value for the reflected light signal from the at least one electrical signal;
wherein the improvement comprises;converting the focused spot of light into an enlarged, elongated spot of light and imaging the filtered light signal to the small area position detector with an anamorphic magnification and field lens system, including a third lens for magnifying the focused spot of light in the position-sensing direction of the position detector and a fourth lens having a relatively short focal length for reducing the focused spot of light in the scanning direction to form the elongated spot of light, wherein the position detector comprises a single detector element including the detector area of less than 20 mm2 and having a relatively small capacitance and dark current and wherein the entire elongated spot of light is uniformly imaged to a discrete extended region of the detector area, to obtain a relatively high signal to noise ratio, the extended region being elongated in a scan dimension substantially orthogonal to the position-sensing direction, wherein spatial noise resulting from variations in sensitivity from point to point in the detector area are averaged. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20)
- scanning a beam of controlled light in a scanning direction at the surface of the object at a first predetermined angle to generate a corresponding reflected light signal;
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2. An imaging system for the high speed, high-resolution 3-D imaging of an object at a vision station to develop dimensional information associated with the object, the system including:
- a source for scanning a beam of controlled light in a scanning direction at the surface of the object at a first predetermined angle to generate a corresponding reflected light signal;
a first set of optical components for creating a relatively small focused spot of light from the reflected light signal, the set of optical components including first and second lenses for receiving the reflected light signal at a second angle and for filtering the received light signal;
measuring means, including a small area position detector having a detector area and having a position-sensing direction substantially orthogonal to the scanning direction for measuring the amount of radiant energy in the reflected light signal and producing at least one electrical signal proportional to the measurement; and
signal processing means for computing a centroid value for the reflected light signal from the at least one electrical signal, wherein the improvement comprises;an anamorphic magnification and field lens system for converting the focused spot of light into an enlarged elongated spot of light, the lens system including a third lens for magnifying the focused spot of light in the position-sensing direction of the position detector and a fourth lens having a relatively short focal length for reducing the focused spot of light in the scanning direction to form the elongated spot of light, wherein a position detector comprises a single detector element including the detector area of less than 20 mm2 and having a relatively small capacitance and dark current and the lens system uniformly imaging the entire elongated spot of light to a discrete extended region of the detector area, to obtain a relatively high signal to noise ratio, the extended region being elongated in a scan dimension substantially orthogonal to the position-sensing direction, wherein spatial noise resulting from variations in sensitivity from point to point in the detector area are averaged. - View Dependent Claims (3)
- a source for scanning a beam of controlled light in a scanning direction at the surface of the object at a first predetermined angle to generate a corresponding reflected light signal;
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15. A method for the high-speed, high-resolution, 3-D imaging of a relatively small object at a vision station to develop dimensional information associated with the object, the method including the steps of:
- scanning a beam of controlled modulated light in a scanning direction at the surface of the object at a first predetermined angle to generate a corresponding reflected light signal;
receiving said reflected light signal at a second angle with a set of optical components for creating a relatively small focused spot of light from the reflected light signal, the set of optical components including first and second lenses, filtering the received light signal with the set of optical components;
measuring the amount of radiant energy in the reflected light signal with a small area position detector having a detector area and having a position-sensing direction substantially orthogonal to the scanning direction and producing at least one electrical signal proportional to the measurement;
demodulating the at least one electrical signal; and
computing a centroid value for the reflected light signal from the at least one demodulated signal;
wherein the improvement comprises;converting the focused spot of light into an enlarged, elongated spot of light and imaging the filtered light signal to the position detector with an anamorphic magnification and field lens system, including a third lens for magnifying the focused spot of light in the position-sensing direction of the position detector and a fourth lens having a relatively short focal length for reducing the focused spot of light in the scanning direction to form the elongated spot of light, wherein the position detector comprises a single detector element including the detector area of less than 20 mm2 and having a relatively small capacitance and dark current and wherein the entire elongated spot of light is uniformly imaged to a discrete extended region of the detector area, to obtain a relatively high signal to noise ratio, the extended region being elongated in a scan dimension substantially orthogonal to the position-sensing direction, wherein spatial noise resulting from variations in sensitivity from point to point in the detector area are averaged.
- scanning a beam of controlled modulated light in a scanning direction at the surface of the object at a first predetermined angle to generate a corresponding reflected light signal;
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21. An imaging system for the high-speed, high-resolution 3-D imaging of a small object at a vision station to develop dimensional information associated with the object, the system comprising:
- a flying spot laser scanner including a light deflector scanning a beam of controlled light in a scanning direction at the surface of the object at a first predetermined triangulation angle of less than 20 degrees to generate a corresponding reflect light signal;
a first set of optical components for creating a relatively small focused spot of light from the reflected light signal, the first set of optical components including first and second lenses for receiving the reflected light signal at a second angle and for filtering the received light signal;
measuring means, including a single, small area position detector having a detector area and having a position-sensing direction substantially orthogonal to the sensing direction for measuring the amount of radiant energy int he reflected light signal and producing at least one electrical signal proportional to the measurement;
signal processing means for computing a centroid value for the reflected light signal from the at least one electrical signal; and
an anamorphic magnification and field lens system for converting the focused spot of light into an enlarged elongated spot of light, the lens system including a third lens for magnifying the focused spot of light in the position-sensing direction of the position detector and a fourth lens having a relatively short focal length for reducing the focused spot of light in the scanning direction to form the elongated spot of light, wherein the position detector comprises a single detector element including the detector are of less than 20 mm2 and having a relatively small capacitance and dark current, the lens system uniformly imaging the entire elongated spot of light to a discrete extended region of the detector area, to obtain a relatively high signal to noise ratio, the extended region being elongated in a scan dimension substantially orthogonal to the position-sensing direction, wherein spatial noise resulting from variations in sensitivity from point to point in the detector area are averaged.
- a flying spot laser scanner including a light deflector scanning a beam of controlled light in a scanning direction at the surface of the object at a first predetermined triangulation angle of less than 20 degrees to generate a corresponding reflect light signal;
Specification