| 摘要 |
PURPOSE:To stabilize exposure highly accurately without the effect of temp. and ambient noise with simple constitution by receiving light source light for illuminating with an optical fiber, propagating the same to a photodetector opposing to the other end face of the optical fiber and feedback-controlling the quantity of the illuminating light. CONSTITUTION:Part of illuminating light for exposure from a light source lamp 1 for illuminating is received at one end face 7a of an optical fiber 7, and is received by the photodetector 2 of a unit 8 opposing to the other end face 7b. Its feedback is controlled by a control device 4 and a lighting device 3, by which the exposure by the lamp 1 is stabilized. In this case, the element 2 does not receive the effect of temp. change owing to the light source 1, and there is no need for any connector between the element 2 and the device 4, the coupling length between which is short and since these are housed in a unit 8, they are difficult to receive the effect of external noise. Hence, the exposure is stabilized highly accurately with the simple constitution using the optical fiber. |
