EP0116856A2 — Improved method and apparatus for correcting imag…

Claim 1

Independent Claim 246 words

In an electron beam recording apparatus having means for deflecting a charged particle beam in the X and Y direction therein, the method for improving the geometric fidelity of the reproduced image comprising the steps of: a) positioning a.charged particle sensitive medium in the path of a charged particle beam to retain a permanent image on said medium, b) projecting the particle beam to form on said medium a test pattern having a predetermined configuration, c) providing a reference alignment image, d) dividing each of the X in and Yin signals into a plurality of non-interactive parallel correction circuits with each arranged to produce a correction signal for a predetermined spatial deviation shown on said medium, e) comparing the deviation of the test pattern image with the reference alignment image for each of said predetermined spatial deviations, by measuring the deviations for a particular deflection distortion at a plurality of predetermined corresponding locations on said images, f) - adjusting each of the X in 'and Y in deflection signal functions in each of said circuits so that the correction signal from each circuit is that for which it was determined, and g) combining the sum of the signals from each of said plurality of correction circuits and summing the same with the X in and Y in signal to produce total correction signals (X c ,Y c ) to the X and Y deflection means whereby the test .pattern image aligns with said reference alignment image.

Claim 2

Dependent Claim 246 words

In an electron beam recording apparatus having means for deflecting a charged particle beam in the X and Y direction therein, the method for improving the geometric fidelity of the reproduced image comprising the steps of: a) positioning a.charged particle sensitive medium in the path of a charged particle beam to retain a permanent image on said medium, b) projecting the particle beam to form on said medium a test pattern having a predetermined configuration, c) providing a reference alignment image, d) dividing each of the X in and Yin signals into a plurality of non-interactive parallel correction circuits with each arranged to produce a correction signal for a predetermined spatial deviation shown on said medium, e) comparing the deviation of the test pattern image with the reference alignment image for each of said predetermined spatial deviations, by measuring the deviations for a particular deflection distortion at a plurality of predetermined corresponding locations on said images, f) - adjusting each of the X in 'and Y in deflection signal functions in each of said circuits so that the correction signal from each circuit is that for which it was determined, and g) combining the sum of the signals from each of said plurality of correction circuits and summing the same with the X in and Y in signal to produce total correction signals (X c ,Y c ) to the X and Y deflection means whereby the test .pattern image aligns with said reference alignment image.

Claim 3

Dependent Claim 65 words

The method of claim 1 wherein said plurality of non-interactive adjustable correction circuits comprise potentiometers which are associated with correction signal components corresponding to predetermined deflection deviations which are corrected by adjusting the amplitude of the corresponding signal component by adjusting a particular potentiometer to provide a calculated correction signal, and monitoring the amplitude of change of the correction signal component while adjusting said potentiometer.

Claim 4

Dependent Claim 42 words

The method of claim 2 wherein said potentiometers are adjusted while providing means for precisely determining the magnitude of the change in the correction signal, and, adjusting the determination of the potentiometer until the magnitude of change corresponds to the correct value.

Claim 5

Dependent Claim 41 words

The method of claim 3 wherein a charged particle beam deflection circuit means is provided and the amplitude of the deflection drive signal is measured by a precision digital voltmeter while making said adjustment until said calculated correction value is attained.

Claim 6

Dependent Claim 32 words

5 .. The method of claim 1 wherein said beam is deflected to form a test pattern configuration having a plurality of precisely definable reference points to form said predetermined corresponding locations.

Claim 7

Dependent Claim 21 words

6 . The method of claim 5 wherein said reference points are represented by a rectangular array of intersecting grid lines.

Claim 8

Independent Claim 26 words

A method according to any of claims 1-6 wherein said adjusting step (f) includes automatically calculating the correction signal for each of said predetermined spatial deviations.

Claim 9

Dependent Claim 204 words

A circuit arrangement for providing in a charged particle beam deflection apparatus having beam deflection means for deflecting a charged particle beam upon the application of X in and Y in deflection signals thereto comprising; a) a source of X in and Y in deflection signals, b) circuit means coupling said X in and Y in signals to said beam deflection means for causing deflection of said charged particle beam, c) a correction circuit means for deriving C x and C y correction signals from X in and Y in input signals coupled thereto, said correction signals each having a plurality of non-interactive correction signal components in parallel, each -of said components corresponding to a predetermined deflection distortion on a recorded image from said beam, d) means for coupling said Xin and Yin deflection signals to said correction circuit means, e) said correction circuit means including multiplier circuits means for deriving second and higher order signal components from said input (X in ,Y in ) signals and for combining the derived multiplier signals to provide a plurality of correction signal components, f) said correction signal components each including a plurality of adjustable circuit members for varying the amplitudes of said associated correction signal component,

Claim 10

Dependent Claim 204 words

A circuit arrangement for providing in a charged particle beam deflection apparatus having beam deflection means for deflecting a charged particle beam upon the application of X in and Y in deflection signals thereto comprising; a) a source of X in and Y in deflection signals, b) circuit means coupling said X in and Y in signals to said beam deflection means for causing deflection of said charged particle beam, c) a correction circuit means for deriving C x and C y correction signals from X in and Y in input signals coupled thereto, said correction signals each having a plurality of non-interactive correction signal components in parallel, each -of said components corresponding to a predetermined deflection distortion on a recorded image from said beam, d) means for coupling said Xin and Yin deflection signals to said correction circuit means, e) said correction circuit means including multiplier circuits means for deriving second and higher order signal components from said input (X in ,Y in ) signals and for combining the derived multiplier signals to provide a plurality of correction signal components, f) said correction signal components each including a plurality of adjustable circuit members for varying the amplitudes of said associated correction signal component,

Claim 11

Dependent Claim 124 words

The circuit arrangement of claim 9 wherein said correction circuit means comprises: a) a second multiplier circuit means; b) means for coupling said first and higher order components and said output correction signals of said first multiplier means to said second multiplier circuit means for providing higher order output correction signal components than is provided by said first multiplier circuit means; and c) circuit means for coupling an output signal from said second multiplier circuit means to said signal combining means. g) said adjustable circuit members each coupled in the circuit at a location for varying the amplitude of said correction signal component after signal multiplication, and h) means for combining said C x and C y correction signals respectively and said deflection signals.

Claim 12

Dependent Claim 128 words

The circuit arrangement of claim 8 wherein said correction circuit means comprises: a) circuit means for providing first and higher order signal components from said first and second input signals X in and Y in respectively; b) a first multiplier circuit means; c) means coupling said first and higher order components to said first multiplier circuit means for providing a plurality of output cdrrection signal components each of 'which is associated with a scanning distortion; e) means for combining said plurality of correction signal components to provide said composite - correction signals X c and Y c ; and f) adjustable circuit means coupled between said first multiplier circuit means and said signal combining means for applying correction signal components of adjustable amplitude to said signal combining means.

Improved method and apparatus for correcting image distortions

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