| 摘要 |
PURPOSE:To enable to accurately and easiy correct the curvature of image surface and the astigmatism among various aberrations by a method wherein the amount of correction of current value, to be given to an astigmatism correction lens and a focus correcting lens, is memorized in the external memory storage together with a positional coordinate, and the value of correction is read out when an exposure is performed. CONSTITUTION:A pattern data transferred to a buffer memory 34 from the external memory storage 32 wherein the patterning data is memorized in advance, and also a controlling data is transferred to a memory 36. Then, based on the indication of a CPU31, the coordinate data of the position to be exposed next and the focus control instruction data corresponding to the positional coordinate of said coordinate data are sent to a register 35 from the buffer memory 34. The memory 36 reads out the contents of the register 35 and sends out the data showing the current of astigmatism correcting lenses 23x and 23y corresponding to said contents of the register 35 and the reference current value of the focus correcting lens 24 to an adder 38. On the other hand, the data of correcting amount of current is transferred to a register 37 from the external memory storage 33 based on the indication of the CPU31, and said data of amount of correction is then outputted to the adder 38, added to the reference data, converted to an alternating signal by a DAC39, and the necessary current is added to the lenses 23x, 23y and 24 respectively through the intermediary of an amplifier 40.
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