| 摘要 |
PURPOSE:To control the amount of exposure ray without an irregularity in exposure light, by synchronizing the performance of shutting OFF measures for a SOR ray with the movement of an irradiation zone. CONSTITUTION:The electronic current IB of an electron storage ring is detected by a current transformer (CT)6 and controls an oscillation frequency (f) of a voltage controlling oscillator (VCO)7. The frequency (f) is input to an incremental/decremental counter 3 via a frequency divider 5. The counter 3 shifts to a subtractive counting mode when the counting reaches the upper limit and to an additive counting mode when reaching the lower limit. The output of the counter 3 forms a current IM by a D/A convertor 2 and a current booster 1 and excites an oscillating magnet not shown in the figure, and makes an orbit of the electronic current IB oscillate. Then a linear irradiation zone of SOR ray begins to oscillate vertically and repeatedly with a velocity corresponding to the electronic current IB, and thereby the inside of a pattern forming zone is uniformly irradiated. An comparator 4 generate its output when an output of the counter 3 stays at an upper (or an lower) limit area when the irradiation zone is outside of the pattern zone. An irregularity in exposure light can be avoided when an exposure adjusting shutter works during the time when this output is generated. |
