Electron beam apparatus

Claim 2

Electron beam apparatus utilizing dynamic focusing in correcting astigmatism and lens curvature conditions comprising in combination: a. means for producing an electron beam; b. first deflecting means responsive to deflecting signals for deflecting the beam in a selected pattern; c. second deflecting means responsive to first correcting signals which are proportional to the cube of the distance the electron beam is deflected from a central axis for correcting astigmatism conditions; d. an electron lens responsive to a second correcting signal for focusing the electron beam; e. first correcting means responsive to said deflecting signals for providing said first correcting signal; and f. second correcting means responsive to said deflecting signals for providing said second correcting signals.

Claim 3

The electron beam apparatus of claim 1 wherein said deflected distance is provided by said first deflecting means.

Claim 4

Apparatus according to claim 2, in which the second deflecting means includes a first field-producing means effective to compress or expand the electron beam in directions corresponding to the axes of deflection of the beam, and second field producing means effective to compress or expand the electron beam in directions corresponding to diagonals to the axes of deflection of the beam.

Claim 5

Apparatus according to claim 3, in which the field producing means are operative to produce an electrostatic field.

Claim 6

Apparatus according to claim 4, in which the field producing means together includes eight electrodes equally spaced around a central axis of the apparatus, the first field producing means consisting of four electrodes each at a respective corner of a square and the second field producing means consisting of four electrodes interleaved between those of the first field producing means.

Claim 7

Apparatus according to claim 3, in which the field producing means are operative to produce a magnetic field.

Claim 8

Apparatus according to claim 6, in which the field producing means together includes eight coils equally spaced around a central axis of the apparatus with the axes of the coils radial, the first field producing means consisting of four coils spaced at 90* intervals around the axis of the apparatus, and the second field producing means consisting of four coils between those of the first field producing means.

Claim 9

Apparatus according to claim 3, in which the first and second field producing means are effective to compress or expand the electron beam in directions respectively parallel to the deflection axes and diagonal to the deflection axes.

Claim 10

Apparatus according to claim 3, in which the electron lens is magnetic and at least one of the deflecting means lies in the magnetic field of the lens, wherein the first and second field producing means are placed so as to be effective to compress or expand the electron beam in directions equally inclined to the deflection axes, to thereby compensate for rotation of the electron beam due to the field generated by the magnetic electron lens.

Claim 11

Apparatus according to claim 8, in which the electron lens is magnetic and at least one of the deflecting means lies in the magnetic field of the lens, wherein the deflection signals are combined electrically to simulate rotation of the deflection axes relative to the directions of the astigmatism correction thereby to compensate for rotation of the electron beam due to the field generated by the electron lens.

Claim 12

Apparatus according to claim 10, in which the signal applied to the first field producing means is a (X2 + Y2) ( Y - X ) and the signal applied to the second field producing means is + or - z Square Root 2 (X2 + Y2) smaller of X and Y where X and Y are the amplitudes of the respective deflection signals or signals derived therefrom and a is a constant of proportionality, the signs of the signal applied to the second means being positive when X and Y are the same sign and negative when they are of different signs.

Claim 13

The electron beam apparatus of claim 2 wherein said second deflecting means is outside the field generated by said lens and is on the same side of said lens as is said first deflecting means.

Claim 14

Electron beam apparatus utilizing dynamic focusing in correction astigmatism and lens curvature conditions comprising in combination: a. means for producing an electron beam; b. first deflecting means responsive to deflecting signals for deflecting the beam in a selected pattern; c. second deflecting means responsive to first correcting signals for correcting astigmatism conditions; d. an electron lens responsive to a second correcting signal for focusing the electron beam, wherein at least one of the deflecting means lie within the field generated by said electron lens; e. first correcting means responsive to said deflecting signals for providing said first correcting signal; f. second correcting means responsive to said deflecting signals for providing said second correcting signals; and g. rotation circuit means for providing said deflecting signals representing a rotated waveform to thereby compensate for the rotation due to the field of electron lens.

Claim 15

Electron beam apparatus utilizing dynamic focusing in correction astigmatism and lens curvature conditions comprising in combination: a. means for producing an electron beam; b. first deflecting means responsive to deflecting signals for deflecting the beam in a selected pattern; c. second deflecting means responsive to first correcting signals for correcting astigmatism conditions; d. an electron lens responsive to a second correcting signal for focusing the electron beam, wherein at least one of the deflecting means lie within the field generated by said electron lens; e. first correcting means responsive to said deflecting signals for providing said first correcting signal; f. second correcting means responsive to said deflecting signals for providing said second correcting signals; and g. rotation circuit means for providing said deflecting signals representing a rotated waveform to thereby compensate for the rotation due to the field of electron lens.

Claim 16

The electron beam apparatus of claim 13 wherein said second correcting signal is proportional to the square of the distance the electron beam is deflected from a central axis.

Claim 17

The electron beam apparatus of claim 14 wherein said second correcting signal is proportional to the sum of the squares of said deflecting signals.

Claim 18

The electron beam apparatus of claim 13 wherein said first correcting signal is proportional to the cube of the distance the electron beam is deflected by said first deflecting means.

Claim 19

The electron beam apparatus of claim 16 wherein said second correcting signal is proportional to the square of the distance the electron beam is deflected by said first deflEcting means.

Claim 20

Electron beam apparatus utilizing dynamic focusing in correcting astigmatism comprising: a. means for producing an electron beam; b. first deflecting means responsive to deflecting signals for deflecting the beam a selected distance in a selected pattern; c. second deflecting means responsive to a correcting signal, indicative of the cube of said distance which said first deflecting means deflects the electron beam, thereby correcting astigmatic conditions; and d. correcting means for generating said correcting signal operatively responsive to said first deflecting means.

Claim 21

Electron beam apparatus utilizing dynamic focusing in correcting astigmatism comprising: a. means for producing an electron beam; b. first deflecting means responsive to deflecting signals for deflecting the beam a selected distance in a selected pattern; c. second deflecting means responsive to a correcting signal, indicative of the cube of said distance which said first deflecting means deflects the electron beam, thereby correcting astigmatic conditions; and d. correcting means for generating said correcting signal operatively responsive to said first deflecting means.

Claim 22

The apparatus of claim 18 wherein said deflecting signals consist of a first deflecting signal X and a second deflecting signal Y and said correcting signal is described by a ( Y - X ) (X2 - Y2) wherein a is a constant of proportionality.