| 摘要 |
PURPOSE:To reduce a size of an apparatus and simplify adjustment at the time of assembly by a method wherein an arc image is formed on incident surfaces of photoelectric conversion elements having segments divided into a plurality of pieces and electric signals from the respective segments are compared with one another to be monitored. CONSTITUTION:An arc image of a discharge lamp is formed on an incident surface of photoelectric conversion elements 20a, 20b by lenses 18a, 18b, and photoelectric currents from segments D1 to D4 of the element 20a and from segments D5 to D8 of the element 20b are converted into voltages by a signal processing circuit 21 so that differences in voltages of the respective segments D1 to D8 are compared with one another to be displayed on a display 22 and monitored. Thus without a light receiver placed on a radiation surface, monitoring is possible as well as since it is not necessary to enlargingly form the images, the number of lenses and mirrors can be decreased so that an apparatus can be reduced in size and adjustment at the time of assembly is simplified. |
