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Browse Prior Art Database

Beam Spot Size Control

IP.com Disclosure Number: IPCOM000093224D
Original Publication Date: 1967-Jul-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Barber, RR: AUTHOR [+2]

Abstract

The control automatically regulates the spot size of electron beam 1 at target 2 by adjusting the current applied to focusing coil 3. The control generates periodic signal 4 at detector 5 responsive to the beam size and beam current by scanning the beam across target 2 having a series of slots 6. Differentiator 7 detects the rise rate of the detector signal to obtain a pulse train. The latter's amplitude, measured by amplitude detector 8, is proportional to the beam current and inversely proportional to the beam size. A signal proportional to the detector signal amplitude is obtained at amplitude detector 9. The gain of amplifier 10 is adjusted so the output of comparator 11 is proportional to the beam amplitude and the difference in the desired beam size and the actual beam size.

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Beam Spot Size Control

The control automatically regulates the spot size of electron beam 1 at target 2 by adjusting the current applied to focusing coil 3. The control generates periodic signal 4 at detector 5 responsive to the beam size and beam current by scanning the beam across target 2 having a series of slots 6. Differentiator 7 detects the rise rate of the detector signal to obtain a pulse train. The latter's amplitude, measured by amplitude detector 8, is proportional to the beam current and inversely proportional to the beam size. A signal proportional to the detector signal amplitude is obtained at amplitude detector 9. The gain of amplifier 10 is adjusted so the output of comparator 11 is proportional to the beam amplitude and the difference in the desired beam size and the actual beam size. This signal is the input to beam focus control 12 to vary the beam focus and adjust the beam spot size at target 2.

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