US3896362A — Light-beam steering apparatus

Claim 1

Independent Claim 350 words

Light beam steering apparatus, comprising: a light source generating a light beam to be steered by deflection thereof; steering mirror means located in the path of said light beam from said source and repositionable at a first speed for deflecting said light beam within a wide range of beam deflectng positions; servo-control means controlling said steering mirror means and comprising a. first input means for receiving command signals corresponding to a required mirror means position, b. feed-back input means connected to said mirror means for receiving feed-back position signals representing actual mirror means position, c. means connected to said first input means and said feed-back input means for generating error signals representing at each instant the departure of the actual mirror position indicated by the feed-back signals from the mirror position required by the command signals, and d. first means connected to said error signal generating means for controlling the movement of said mirror means in dependence upon said error signals; secondary beam control means simultaneously responsive to the same error signals as said mirror controlling means for simultaneously deflecting said beam before it reaches said steering mirror means, said secondary beam control means including a. a secondary deflection system positioned in the path of said light beam between said source and said steering mirror means for accurately deflecting said beam at a faster second speed within a narrower range of beam positions incident on the steering mirror means, and b. second means defining a secondary control circuit connected between said error signal generating means and said secondary deflection system and responsive to the same said error signals for causing said secondary deFlection system to correct the beam position in accordance with said same error signals; whereby said secondary beam control means rapidly deflects, within its narrow range, the beam incident on the steering mirror means to dynamically compensate for instantaneous deflection error in the beam emerging from such steering mirror means, simultaneously with at least partial execution by the slower but wider range steering mirror means of moves toward each of a rapidly commanded series of beam deflecting positions.

Claim 2

Dependent Claim 350 words

Light beam steering apparatus, comprising: a light source generating a light beam to be steered by deflection thereof; steering mirror means located in the path of said light beam from said source and repositionable at a first speed for deflecting said light beam within a wide range of beam deflectng positions; servo-control means controlling said steering mirror means and comprising a. first input means for receiving command signals corresponding to a required mirror means position, b. feed-back input means connected to said mirror means for receiving feed-back position signals representing actual mirror means position, c. means connected to said first input means and said feed-back input means for generating error signals representing at each instant the departure of the actual mirror position indicated by the feed-back signals from the mirror position required by the command signals, and d. first means connected to said error signal generating means for controlling the movement of said mirror means in dependence upon said error signals; secondary beam control means simultaneously responsive to the same error signals as said mirror controlling means for simultaneously deflecting said beam before it reaches said steering mirror means, said secondary beam control means including a. a secondary deflection system positioned in the path of said light beam between said source and said steering mirror means for accurately deflecting said beam at a faster second speed within a narrower range of beam positions incident on the steering mirror means, and b. second means defining a secondary control circuit connected between said error signal generating means and said secondary deflection system and responsive to the same said error signals for causing said secondary deFlection system to correct the beam position in accordance with said same error signals; whereby said secondary beam control means rapidly deflects, within its narrow range, the beam incident on the steering mirror means to dynamically compensate for instantaneous deflection error in the beam emerging from such steering mirror means, simultaneously with at least partial execution by the slower but wider range steering mirror means of moves toward each of a rapidly commanded series of beam deflecting positions.

Claim 3

Dependent Claim 19 words

Light beam steering apparatus as claimed in claim 1 in which the secondary deflection system comprises an electro-optical device.

Claim 4

Dependent Claim 111 words

Light beam apparatus as claimed in claim 1 wherein said steering mirror means comprises a steering mirror movable for beam deflection in at least one coordinate direction, and said feed-back position signals comprise a train of position pulses from the steering mirror and said servo-control means comprises, for said mirror, means for generating from the command signals a train of command pulses at a rate representing the required velocity of movement of the beam in the co-ordinate direction controlled by that mirror, and said error signal generating means comprises an error scaler for that co-ordinate direction to which the corresponding trains of feed-back pulses and command pulses are applied in opposition.

Claim 5

Dependent Claim 65 words

Apparatus as claimed in claim 3 in which the means for generating the train of command pulses comprise a buffer store into which the magnitude of a vector component of a desired movement can be placed and a binary rate multiplier supplied with the output of the buffer store and with rate-determining pulses from a clock common to the binary rate multipliers for both mirrors.

Claim 6

Dependent Claim 34 words

Apparatus as claimed in claim 3 including synch pulse controlled logic by which the train of feed-back pulses and the corresponding train of command pulses are synchronized to have a predetermined phase difference therebetween.

Claim 7

Dependent Claim 60 words

Apparatus as claimed in claim 1 in which said steering mirror means comprises a steering mirror and the means for controlling the movement of the mirror comprises an electromagnetic drive for the steering mirror comprising a drive coil, and a driving circuit for supplying a driving current to the drive coil, said driving circuit being controlled by said error signals.

Claim 8

Dependent Claim 39 words

Apparatus as claimed in claim 1 including further control means for said secondary deflection system comprising a matrix multiplication device and further including adding means connecting said control circuit and said further control means to said secondary deflection systme.

Claim 9

Dependent Claim 176 words

Apparatus as claimed in claim 7 including error signal generating means for each of first and second degrees of freedom of beam deflection, said further control means including additional error signal generating means for each said degree of freedom of beam deflection, said matrix multiplication device being coupled to said additional error signal generating means for receiving error signals therefrom and comprising a pair of multipliers for each said degree of freedom, each said pair receiving one such error signal, means applying multiplier values separately to said multipliers, one said adding means being provided for each such degree of freedom and being provided with inputs from a multiplier from each said pair and an error signal from said error signal generating means for one said degree of freedom of beam deflection, a given said adding means providing a combined error signal output to said secondary deflection system so as to superpose localized high speed control of the secondary deflection on the beam deflection control exercised by said servocontrol means and said secondary deflection system in combination.

Claim 10

Dependent Claim 74 words

Light beam steering apparatus as claimed in claim 8 including an oscillator having a pair of opposite polarity outputs and switch means coupling such opposite polarity outputs to the outputs of respective ones of said adding means in response to absence of command signals for causing said beam to execute a small circular movement when it would otherwise be idle and further including means for blocking said beam when executing such small circular movment.

Claim 11

Dependent Claim 104 words

Light-beam steering apparatus as claimed in claim 1 wherein said feedback input means is coupled to said steering mirror means by first and second feedback generating means, one for each coordinate direction of deflection of said mirror means, each of said feedback generating means comprising a Michelson interferometer device having one member which moves with the steering mirror means and a fringe counter for counting the movement of the interference fringes resulting from changes in the position of the mirror, the output of said fringe counter forming the feedback position signals for control of the movement of the mirror in the corresponding coordinate direction.

Claim 12

Dependent Claim 235 words

Apparatus as claimed in claim 1 in which said first input means comprises a binary rate multiplier for receiving magnitude command signals, means applying rate determining clock pulses, representing the required speed of movement of the beam, to said binary rate multiplier, a pair of AND gates responsive to the output signal of said binary rate multiplier and means alternatively applying a further input to said AND gates in accord with the sign of the required direction of beam movement, and wherein said means for generating error signals includes a pair of OR gates driven by respective ones of said AND gates and an error scaler energizable in one direction by one said OR gate and energizable in the opposite direction by the other of said OR gates, said feedback input means including further AND gates alternatively actuable in response to the actual movement of said steering mirror means in opposite directions, said further AND gates being coupled to repective further inputs of said OR gates, a clock source for supplying out of phase sync pulses and synchronizing means responsive to said feedback position signals and providing gating outputs to said further AND gates for causing same to slightly delay and synchronize passage of said feedback position signals therethrough to said OR gates, said means for controlling the movement of the mirror means including a drive circuit responsive to the output of said error scaler.

Claim 13

Dependent Claim 125 words

Light beam steering apparatus as claimed in claim 11, including a third pair of AND gates responsive to respective ones of said OR gates, a pair of flip-flops having inputs from respective ones of said third AND gates and having clock inputs from opposite ones of said OR gates and including output gate means for each of said pair of flip-flops further responsive to ones of said OR gates and means coupling said output gate means to said driving circuit for applying a relative velocity signal to said driving circuit to so increase mirror driving current that movement of the mirror away from its prescribed position is rapidly damped, said relative velocity signal representing the actual velocity of the mirror relative to its prescribed velocity.

Claim 14

Dependent Claim 243 words

Light beam steering apparatus comprising a light source emitting a light beam, means comprising a pair of steering mirrors in the path of said light beam for steering the beam, a secondary deflection system in the path of said beam between said source and steering mirrors for deflecting said beam prior to incidence on said steering mirrors, mirror control means for said steering mirrors, interferometer means connected to each of said mirrors to detect movement thereof, fringe-counting means connected to said interferometer means to generate a digital signal representing the position of each of said mirrors, feed-back means feeding said digital position signals to said mirror control means, means applying digital position command signals to said mirror control means, said mirror control means comprising an error-detecting means receiving said digital position command signals and for generating an error signal representing the difference between the position command signals and the digital position signals from the fringe-counting means, means applying said error signal to said secondary deflection system for controlling beam deflection thereby, driving means for moving said mirrors, said mirror control means further comprising drive circuit means responsive to said error signal for supplying drivin currents to said driving means, an intensity modulator also in the path of said beam and means for deriving a velocity signal representing the speed of movement of the beam and means applying said velocity signal to said intensity modulator for compensating beam intensity for increased beam deflection velocity.

Claim 15

Dependent Claim 243 words

Light beam steering apparatus comprising a light source emitting a light beam, means comprising a pair of steering mirrors in the path of said light beam for steering the beam, a secondary deflection system in the path of said beam between said source and steering mirrors for deflecting said beam prior to incidence on said steering mirrors, mirror control means for said steering mirrors, interferometer means connected to each of said mirrors to detect movement thereof, fringe-counting means connected to said interferometer means to generate a digital signal representing the position of each of said mirrors, feed-back means feeding said digital position signals to said mirror control means, means applying digital position command signals to said mirror control means, said mirror control means comprising an error-detecting means receiving said digital position command signals and for generating an error signal representing the difference between the position command signals and the digital position signals from the fringe-counting means, means applying said error signal to said secondary deflection system for controlling beam deflection thereby, driving means for moving said mirrors, said mirror control means further comprising drive circuit means responsive to said error signal for supplying drivin currents to said driving means, an intensity modulator also in the path of said beam and means for deriving a velocity signal representing the speed of movement of the beam and means applying said velocity signal to said intensity modulator for compensating beam intensity for increased beam deflection velocity.

Claim 16

Dependent Claim 294 words

Light beam steering apparatus comprising a light source generating a light beam to be steered, a main deflection system comprising a pair of steering mirrors positioned in the path of the light beam from the source and movable for deflecting the beam through a range of deflection, servo-control means controlling said mirrors and comprising (a) first input means for receiving command signals representing a series of commanded steering mirror position, (b) feed-back input means coupled to the mirrors to receive feed-back position signals representing actual steering mirror positions, and (c) output means coupled to and effecting synchronous displacement of the steering mirrors for displacing the light beam toward successively commanded positions defining a pattern, (d) means responsive to said first and feed-back input means for generating an error signal representing the departure of the actual position of the mirrors from the desired position and applying said error signal to said output means, and (e) means generating a signal representative of beam tracing velocity, an intensity modulator in the path of the light beam, means connecting said intensity modulator to said control means and responsive to said velocity signal for causing the intensity modulator to positively compensate the intensity of the light beam for instantaneous differences in said tracing velocity, a secondary deflection system also in the path of the light beam and preceding said steering mirrors for deflecting the beam prior to incidence on said steering mirrors, means defining a secondary control circuit coupled between said control means and said secondary deflection system and responsive to the same said error signal moving said steering mirrors for causing said secondary deflection system to simultaneously correct the position of the beam in accordance with said error signal and in compensation for lags in steering mirror movement.

Claim 17

Dependent Claim 294 words

Light beam steering apparatus comprising a light source generating a light beam to be steered, a main deflection system comprising a pair of steering mirrors positioned in the path of the light beam from the source and movable for deflecting the beam through a range of deflection, servo-control means controlling said mirrors and comprising (a) first input means for receiving command signals representing a series of commanded steering mirror position, (b) feed-back input means coupled to the mirrors to receive feed-back position signals representing actual steering mirror positions, and (c) output means coupled to and effecting synchronous displacement of the steering mirrors for displacing the light beam toward successively commanded positions defining a pattern, (d) means responsive to said first and feed-back input means for generating an error signal representing the departure of the actual position of the mirrors from the desired position and applying said error signal to said output means, and (e) means generating a signal representative of beam tracing velocity, an intensity modulator in the path of the light beam, means connecting said intensity modulator to said control means and responsive to said velocity signal for causing the intensity modulator to positively compensate the intensity of the light beam for instantaneous differences in said tracing velocity, a secondary deflection system also in the path of the light beam and preceding said steering mirrors for deflecting the beam prior to incidence on said steering mirrors, means defining a secondary control circuit coupled between said control means and said secondary deflection system and responsive to the same said error signal moving said steering mirrors for causing said secondary deflection system to simultaneously correct the position of the beam in accordance with said error signal and in compensation for lags in steering mirror movement.

Claim 18

Dependent Claim 105 words

Apparatus as claimed in claim 14 in which each steering mirror has means for generating a position feed back signal in the form of a train of position pulses and the servo control means comprises, for each mirror, means for generating a train of command pulses at a rate representing the required velocity of movement of the beam in the co-ordinate direction controlled by that mirror, the two trains of pulses being applied in opposition to an error scaler which determines the direction in which the mirror is driven in dependence upon the position of the mirror relative to that commanded by the command pulses.

Claim 19

Dependent Claim 64 words

Apparatus as claimed in claim 15 wherein the means for generating the train of command pulses comprise a buffer store into which the magnitude of a vector component of a desired movement can be placed and a binary rate multiplier supplied with rate-determining pulses from a clock common to the binary rate multipliers for both mirrors and with the output of the buffer store.

Claim 20

Dependent Claim 22 words

Apparatus as claimed in claim 15 in which the two trains of pulses are synchronized to have a pre-determined phase difference therebetween.

Claim 21

Dependent Claim 60 words

Apparatus as claimed in claim 15 in which the servo-control means comprises means for comparing the two trains of pulses to determine the direction of movement of the mirror relative to the movement Prescribed by the command pulses, said means being connected to decrease the driving force applied to the mirror when it is moving towards the instantaneous prescribed position.

Claim 22

Dependent Claim 50 words

Apparatus as claimed in claim 15 in which the means for generating a position feed back signal comprise a Michelson interferometer device one member of which moves with the mirror and a fringe counter for counting the movement of the interference fringes resulting from change in position of the mirror.

Claim 23

Dependent Claim 40 words

Apparatus as claimed in claim 15 wherein each mirror has an electromagnetic drive including a drive coil connected to a driving circuit which supplies a driving current to the drive coil, the driving circuit being controlled by the error scaler.

Claim 24

Dependent Claim 16 words

Apparatus as claimed in claim 14 in which the secondary deflection system comprises an electo-optical device.

Claim 25

Dependent Claim 73 words

Apparatus as claimed in claim 20 in which the servocontrol means comprises comparison means connected to receive the two trains of pulses and coupled to the driving circuit to supply thereto relative velocity signals representing the direction of movement of the mirror relative to the movement prescribed by the commmand pulses, said relative velocity signals acting to decrease the driving current when the deviation of the mirror from the prescribed path is decreasing.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-07-21	1979-01-20	1979-07-22	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-07-21	1983-01-20	1983-07-22	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-07-21	1987-01-20	1987-07-22	$7700.00	Window Closed / Lapsed

Light-beam steering apparatus

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