PURPOSE: To enable correction of a deflection astigmatism which is adapted to an optical charged-particle system by supplying a correction signal, which is obtained by figuring out the sum of signals proportional to the squares of a horizontal and a vertical deflection signal (x) and (y), a signal proportional to (x) by (y) multiplied, and signals proportional to (x) and (y), to a deflector.
CONSTITUTION: Deflection signals produced by a signal producer 12 is given to a deflector 9 so as to deflect charged particles to a deflection point (x,y). On the other hand, an amplifier and the like are provided between a signal generator 12 and a deflector 9, and signals (x) and (y) sent from the generator 12 are converted into signals (x2-y2) and (xy) by means of a square-law circuit 13, a substracting circuit 14 and a multiplying circuit 15. Next, a signal corresponding to the correction amount is obtained by means of a multiplying adding circuit 17, from the signals (x2-y2) and (xy), the signals (x) and (y), and coefficients (ax,bx...dy) which are given in a register 16 beforehand. After that, an astigmatism correction at an arbitrary point (x,y) can be performed by giving the above signal, which corresponds to the correction amount, to an astigmatism correcting aid 7.
MIYAZAKI MASARU
UNO TAIDOU
NIPPON TELEGRAPH & TELEPHONE
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| JPS5111574A | 1976-01-29 | |||
| JPS52124873A | 1977-10-20 | |||
| JPS57105953A | 1982-07-01 |