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US 4,142,132 AGranted
Method and means for dynamic correction of electrostatic deflector for electron beam tube
AssigneeControl Data Corporation
InventorKenneth J. Harte
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AssigneeControl Data Corporation
InventorKenneth J. Harte
Estimating the term…
An electron beam tube electrostatic deflection system and method of operation is described. The electron beam tube includes an eight-fold deflector and means are provided for applying two different quadrupole correction electric potentials to selected ones of the eight-fold deflector members and for applying an octupole correction electrical potential to all eight deflector members. In the preferred embodiment, the quadrupole and octupole correction potentials applied to one set of four deflector members are represented by the respective values (V.sub.2c - V), (-V.sub.2c - V), (V.sub.2c - V) and (-V.sub.2c - V), and the quadrupole and octupole correction potentials applied to the second set of four deflector members are represented respectively by the values (V.sub.2s + V), (-V.sub.2s + V), (V.sub.2s + V) and (-V.sub.2s + V) where the quadrupole correction electric potential V.sub.2c = [A.sub.2c (V.sub.x.sup.2 - V.sub.y.sup.2)]/V.sub.c, (1) the quadrupole correction electric potential V.sub.2s = (2A.sub.2s V.sub.x V.sub.y)/V.sub.c, (2) and the octupole correction potential V applied to all eight of the eight-fold deflector members is given by the expression V = [A.sub.4 (V.sub.x.sup.4 - 6V.sub.x.sup.2 V.sub.y.sup.2 + V.sub.y.sup.4)]/4V.sub.c.sup.3 (3) where A.sub.2c, A.sub.2s and A.sub.4 are constants, V.sub.x and V.sub.y are the x and y deflection electric potentials, and -V.sub.c is the cathode voltage of the electron gun used in the electron beam tube apparatus. In preferred arrangements, the electrostatic deflection system further includes means for applying a dynamic focusing electric potential to the objective lens assembly of the electron beam tube apparatus in conjunction with both the correction and deflection electric potentials described above. The dynamic focusing electric potential is V.sub.OBJ(DF) = V.sub.OBJ(0) + [(A.sub.DF (V.sub.x.sup.2 + V.sub.y.sup.2))/V.sub.c ] (4) where A.sub.DF is a constant and V.sub.OBJ(O) is the uncorrected value of the direct current objective lens supply voltage. Both deflection and correction electric potentials are developed by an eight-fold deflector voltage generator which includes as its heart a novel octupole-quadrupole generator.
An electron beam tube electrostatic deflection system comprising an evacuated housing, electron gun means disposed at one end of the evacuated housing for producing a beam of electrons, lens means secured within the evacuated housing intermediate the electron gun means and the opposite end of the housing and disposed along the path of the beam of electrons for focusing and centering the beam of electrons into a finely focused pencil-like beam of electrons, eight-fold deflector means secured within the housing and disposed about the path of the finely focused beam of electrons, said eight-fold deflector means comprising eight electrically conductive spaced-apart members which are electrically isolated one from the other and annularly arranged around the center electron beam path, means for applying deflection electric potentials to the respective members of the eight-fold deflector means for electrostatically deflecting the finely focused electron beam to a desired point on a target plane located at an opposite end of the evacuated housing from the electron gun means, and means for applying correction electric potentials to the respective members of the eight-fold deflector means in conjunction with the deflection electric potentials to minimize electron beam spot aberration at the target plane, said means for applying correction electric potentials to the respective members of the eight-fold deflector means comprising means for applying two different quadrupole correction electric potentials to selected ones of the eight-fold deflector members and means for applying an octupole correction electric potential to all eight deflector members.
A method of correcting for electron beam aberrations in an electron beam tube electrostatic deflection system which comprises an evacuated housing, electron gun means disposed at one end of the evacuated housing for producing a beam of electrons, lens means secured within the evacuated housing intermediate the electron gun means and the opposite end of the housing and disposed along the path of the beam of electrons for focusing and centering the beam of electrons into a finely focused pencil-like beam of electrons, eight-fold deflector means secured within the housing and disposed about the path of the finely focused beam of electrons, said eight-fold deflector means comprising eight electrically conductive spaced-apart members which are electrically isolated one from the other and annularly arranged around the center electron beam path, means for applying deflection electric potentials to the respective members of the eight-fold deflector means for electrostatically deflecting the finely focused electron beam to a desired point on a target plane located at an opposite end of the evacuated housing from the electron gun means, and means for applying correction electric potentials to the respective members of the eight-fold deflector means in conjunction with the deflection electric potentials to minimize electron beam spot aberration at the target plane;
An octupole correction potential signal generator for an electron beam tube electrostatic deflection system comprising first multiplier circuit means responsive to a deflection voltage signal v.sub.x for multiplying the v.sub.x signal by itself to derive a signal v.sub.x.sup.2, second multiplier circuit means responsive to a deflection voltage signal v.sub.y for multiplying the v.sub.y signal by itself to derive a signal v.sub.y.sup.2, first and second summing amplifier means both responsive to said v.sub.x.sup.2 signal, first and second operational amplifier means having the transfer functions -(3 + 2.sqroot.2) and -(3 - 2.sqroot.2) respectively connected intermediate the output of the second multiplier circuit means and the second summing input terminals of said first and second summing circuit means respectively for deriving two separate signals having the values -(3 + 2.sqroot.2) v.sub.y.sup.2 and -(3 - 2.sqroot.2) v.sub.y.sup.2 respectively and supplying the same to the respective first and second summing circuit means, said first and second summing circuit means serving to sum together the v.sub.x.sup.2 signals with the signals from the respective first and second operational amplifier means to derive two separate signals having the values
An electron beam tube electrostatic deflection system comprising an eight-fold deflector assembly for securement within an evacuated housing in a manner so as to be disposed about the path of a finely focused beam of electrons, said eight-fold deflector assembly comprising eight electrically conductive spaced-apart members which are electrically isolated one from the other and annularly arranged around a center axis defining the electron beam path, means for applying deflection electric potentials to the respective members of the eight-fold deflector means for electrostatically deflecting the finely focused electron beam to a desired point on a target plane located at an opposite end of the evacuated housing from the source of the electron beam, and means for applying correction electric potentials to the respective members of the eight-fold deflector means in conjunction with the deflection electric potentials to minimize electron beam spot aberration at the target plane, said means for applying correction electric potentials to the respective members of the eight-fold deflector means comprising means for applying two different quadrupole correction electric potentials to selected ones of the eight-fold deflector members and means for applying an octupole correction electric potential to all eight deflector members.
A charged particle beam tube electrostatic deflection system comprising an evacuated housing, gun means disposed at one end of the evacuated housing for producing a beam of charged particles, lens means secured within the evacuated housing intermediate the gun means and the opposite end of the housing and disposed along the path of the beam of charged particles for focusing and centering the beam of charged particles into a finely focused pencil-like beam of charged particles, eight-fold deflector means secured within the housing and disposed about the path of the finely focused beam of charged particles, said eight-fold deflector means comprising eight electrically conductive spaced-apart members which are electrically isolated one from the other and annularly arranged around the center charged particle beam path, means for applying deflection electric potentials to the respective members of the eight-fold deflector means for electrostatically deflecting the finely focused charged particle beam to a desired point on a target plane located at an opposite end of the evacuated housing from the electron gun means, and means for applying correction electric potentials to the respective members of the eight-fold deflector means in conjunction with the deflection electric potentials to minimize charged particle beam spot aberration at the target plane, said means for applying correction electric potentials to the respective members of the eight-fold deflector means comprising means for applying two different quadrupole correction electric potentials to respective ones of the eight-fold deflector members and means for applying an octupole correction electric potential to all eight deflector members.
A charged particle beam tube electrostatic deflection system comprising an eight-fold deflector assembly for securement within an evacuated housing in a manner so as to be disposed about the path of a finely focused beam of charged particles, said eight-fold deflector assembly comprising eight electrically conductive spaced-apart members which are electrically isolated one from the other and annularly arranged around a center axis defining the charged particle beam path, means for applying deflection electric potentials to the respective members of the eight-fold deflector means for electrostatically deflecting the finely focused charged particle beam to a desired point on a target plane located at an opposite end of the evacuated housing from the source of the charged particle beam, and means for applying correction electric potentials to the respective members of the eight-fold deflector means in conjunction with the deflection electric potentials to minimize charged particle beam spot aberration at the target plane, said means for applying correction electric potentials to the respective members of the eight-fold deflector means comprising means for applying two different quadrupole correction electric potentials to selected ones of the eight-fold deflector members and means for applying an octupole correction electric potential to all eight deflector members.
Dependencies are inferred from the claim text.