Apparatus and method providing improved control of a laser beam

Claim 2

Apparatus for use in angularly deflecting and intensity modulating an incident laser beam comprising: (a) an acousto-optic cell controllable by a drive signal for angularly deflecting and intensity modulating a laser beam incident thereon having an effective diameter D; (b) means for producing a drive signal which varies in frequency over a range Δf to cause the incident laser beam to be deflected through an angular range Δθ; and (c) means, operable during the variation of the drive signal through said frequency range Δf, for varying the amplitude of the drive signal in accordance with a number of pixels N pix of information, said number of pixels (N pix ) being substantially greater than a resolution parameter N res defined as ##EQU6## where V s is the acoustic velocity of said acousto-optic cell, and τ is the beam separation constant.

Claim 3

Apparatus as claimed in claim 1 wherein said drive signal producing means includes means for producing a drive signal comprised of a series of frequency components, each of which frequency components is effective to cause the incident laser beam to be deflected along a respective angular direction.

Claim 4

Apparatus as claimed in claim 1 wherein said drive signal producing means includes means for producing a drive signal that is continuously variable in frequency over the frequency range Δf for causing the incident laser beam to be continuously deflected through the angular range Δθ.

Claim 5

Apparatus as claimed in claim 1 wherein the time T c taken taken for the incident laser beam to be deflected through the angular range Δθ divided by the number of pixels N pix is approximately equal to the access time τ of said acousto-optic cell which is defined as τ=D/V.sub.s.

Claim 6

Apparatus as claimed in claim 4 wherein said drive signal producing means includes means for producing a drive signal comprised of a series of frequency components, each of which frequency components is effective to cause the incident laser beam to be deflected along a respective angular direction.

Claim 7

Apparatus as claimed in claim 4 wherein said drive signal producing means includes means for producing a drive signal that is continuously variable in frequency over the frequency range Δf for causing the incident laser beam to be continuously deflected through the angular range Δθ.

Claim 8

Apparatus for use in controlling the operation of a laser beam to expose information on a high contrast recording material disposed at an image plane, said apparatus comprising: (a) acousto-optic cell means characterized by an acoustic velocity V s for angularly deflecting and intensity modulating an incident laser beam having an effective diameter D; (b) means for producing a drive signal to control the operation of said acousto-optic cell, said drive signal varying in frequency over a range Δf to cause the incident laser beam to be deflected through an angular range Δθ; (c) means for varying the amplitude of the drive signal to cause the deflected laser beam to be intensity modulated in accordance with a number of pixels N pix of information as the laser beam is deflected through the angular range Δθ, the number of pixels N pix being substantially greater than a resolution parameter N res defined as ##EQU7## where ε is the beam separation constant; and (d) means for focusing the deflected and modulated laser beam in the image plane to cause the laser beam to scan across the image plane and to expose information on the high contrast recording material disposed thereat.

Claim 9

Apparatus for use in controlling the operation of a laser beam to expose information on a high contrast recording material disposed at an image plane, said apparatus comprising: (a) acousto-optic cell means characterized by an acoustic velocity V s for angularly deflecting and intensity modulating an incident laser beam having an effective diameter D; (b) means for producing a drive signal to control the operation of said acousto-optic cell, said drive signal varying in frequency over a range Δf to cause the incident laser beam to be deflected through an angular range Δθ; (c) means for varying the amplitude of the drive signal to cause the deflected laser beam to be intensity modulated in accordance with a number of pixels N pix of information as the laser beam is deflected through the angular range Δθ, the number of pixels N pix being substantially greater than a resolution parameter N res defined as ##EQU7## where ε is the beam separation constant; and (d) means for focusing the deflected and modulated laser beam in the image plane to cause the laser beam to scan across the image plane and to expose information on the high contrast recording material disposed thereat.

Claim 10

Apparatus as claimed in claim 7 wherein said drive signal producing means includes means for producing a drive signal comprised of a series of frequency components, each of which frequency components is effective to cause the incident laser beam to be deflected along a respective angular direction.

Claim 11

Apparatus as claimed in claim 8 wherein said amplitude varying means includes means for producing an information signal representative of alphanumeric characters and/or like symbols, and means for modulating the amplitude of said frequency components in accordance with said information signal.

Claim 12

Apparatus as claimed in claim 9 further comprising means for adjusting the effective diameter D of the incident laser beam.

Claim 13

Apparatus as claimed in claim 7 wherein said drive signal producing means includes means for producing a drive signal that is continuously variable in frequency over the frequency range Δf for causing the incident laser beam to be continuously deflected through the angular range Δθ.

Claim 14

Apparatus as claimed in claim 11 wherein said amplitude varying means includes means for producing an information signal representative of alphanumeric characters and/or like symbols, and means for modulating the amplitude of said frequency components in accordance with said information signal.

Claim 15

Apparatus as claimed in claim 12 further comprising means for adjusting the effective diameter D of the incident laser beam.

Claim 16

Apparatus as claimed in claim 7 comprising the further improvement wherein the time T c taken taken for the incident laser to be deflected through the angular range Δθ divided by the number of pixels N pix is approximately equal to the access time τ of said acousto-optic cell which is defined as τ=D/V.sub.s.

Claim 17

Laser control apparatus for use in angularly deflecting and intensity modulating a laser beam comprising: (a) an acousto-optic cell for angularly deflecting and intensity modulating, in response to a drive signal applied thereto, a laser beam incident thereon and having an effective diameter D; (b) means for focusing said deflected beam in an image plane to cause said laser beam to scan across said image plane upon being deflected by said acousto-optic cell; (c) means for producing a drive signal that varies in frequency through a range Δf that is effective to cause the incident laser beam to scan a length L across the image plane; and (d) means for varying the amplitude of the drive signal to cause the deflected laser beam to be intensity modulated in accordance with a number of pixel N pix of information while the deflected beam is scanned across the length L in the image plane, the number of pixels N pix being substantially greater than a resolution parameter N res defined as ##EQU8## where V s is the acoustic velocity of said acousto-optic cell and ε is the beam separation constant.

Claim 18

Laser control apparatus for use in angularly deflecting and intensity modulating a laser beam comprising: (a) an acousto-optic cell for angularly deflecting and intensity modulating, in response to a drive signal applied thereto, a laser beam incident thereon and having an effective diameter D; (b) means for focusing said deflected beam in an image plane to cause said laser beam to scan across said image plane upon being deflected by said acousto-optic cell; (c) means for producing a drive signal that varies in frequency through a range Δf that is effective to cause the incident laser beam to scan a length L across the image plane; and (d) means for varying the amplitude of the drive signal to cause the deflected laser beam to be intensity modulated in accordance with a number of pixel N pix of information while the deflected beam is scanned across the length L in the image plane, the number of pixels N pix being substantially greater than a resolution parameter N res defined as ##EQU8## where V s is the acoustic velocity of said acousto-optic cell and ε is the beam separation constant.

Claim 19

Apparatus as claimed in claim 15 wherein said amplitude varying means includes (1) means for producing an information signal representative of information to be exposed in the image plane, and (2) means for amplitude modulating the deflection signal in accordance with said information signal.

Claim 20

Apparatus as claimed in claim 16 wherein said information signal producing means includes means for producing an information signal representative of alphanumeric characters and/or like symbols.

Claim 21

Apparatus as claimed in claim 17 wherein said drive signal producing means includes means for producing a drive signal comprised of a series of frequency components, each of which frequency components is effective to cause the incident laser beam to be deflected along a respective angular direction.

Claim 22

Apparatus as claimed in claim 18 comprising the further improvement wherein said drive signal producing means includes means for producing a drive signal that is continuously variable in frequency over the frequency range Δf for causing the incident laser beam to be continuously deflected through the angular range Δθ.

Claim 23

Apparatus as claimed in claim 15 comprising the further improvement wherein the time T c taken for the incident laser to be deflected through the angular range Δθ divided by the number of pixels N pix is approximately equal to the access time τ of said acousto-optic cell which is defined as τ=D/V.sub.s.

Claim 24

Laser writing apparatus for use in writing alphanumeric characters and/or like symbols on a high contrast recording material disposed at an image plane, said apparatus comprising: (a) an acousto-optic cell for intensity modulating and angularly deflecting, in response to a drive signal applied thereto, a laser beam incident thereon having an effective diameter D; (b) means for producing a laser beam incident on said acousto-optic cell; (c) means for focusing said modulated and deflected laser beam in said image plane so that said focused beam will be scanned across said image plane upon deflection by said acousto-optic cell; (d) means for producing an information signal containing alphanumeric character and/or like symbol information; (e) means for producing a drive signal which varies in frequency over a range Δf to cause the incident laser beam to be deflected through an angular range Δθ; and (f) means for varying the amplitude of said drive signal in accordance with said information signal to cause the intensity of the deflected laser beam to vary in accordance with a number of pixel N pix of information per angular range Δθ, being substantially greater than a resolution parameter N res defined by ##EQU9## where V s is the acoustic velocity of said acousto-optic cell and τ is the beam separation constant.

Claim 25

Laser writing apparatus for use in writing alphanumeric characters and/or like symbols on a high contrast recording material disposed at an image plane, said apparatus comprising: (a) an acousto-optic cell for intensity modulating and angularly deflecting, in response to a drive signal applied thereto, a laser beam incident thereon having an effective diameter D; (b) means for producing a laser beam incident on said acousto-optic cell; (c) means for focusing said modulated and deflected laser beam in said image plane so that said focused beam will be scanned across said image plane upon deflection by said acousto-optic cell; (d) means for producing an information signal containing alphanumeric character and/or like symbol information; (e) means for producing a drive signal which varies in frequency over a range Δf to cause the incident laser beam to be deflected through an angular range Δθ; and (f) means for varying the amplitude of said drive signal in accordance with said information signal to cause the intensity of the deflected laser beam to vary in accordance with a number of pixel N pix of information per angular range Δθ, being substantially greater than a resolution parameter N res defined by ##EQU9## where V s is the acoustic velocity of said acousto-optic cell and τ is the beam separation constant.

Claim 26

Apparatus as claimed in claim 21 wherein said drive signal producing means includes means for producing a drive signal that is continuously variable in frequency over the frequency range Δf for causing the incident laser beam to be continuously deflected through the angular range Δθ.

Claim 27

Apparatus as claimed in claim 21 wherein said drive signal producing means includes means for producing a drive signal comprised of a series of frequency components, each of which frequency components is effective to cause the incident laser beam to be deflected along a respective angular direction.

Claim 28

Apparatus as claimed in claim 21 comprising the further improvement wherein the time T c taken taken for the incident laser to be deflected through the angular range Δθ divided by the number of pixels N pix is approximately equal to the access time τ of said acousto-optic cell which is defined as τ=D/V.sub.s.

Claim 31

A method as claimed in claim 25 wherein the amplitude of the drive signal is varied in accordance with an information signal representative of alphanumeric characters and/or like symbols.