| 摘要 |
PURPOSE:To enable calculation of a desired local transmission factor of a pericle, by measuring a light beam reflected with a half mirror and a light beam reflected with a pericle or transmitted therethrough after passing through the half mirror with respective light intensity measuring devices. CONSTITUTION:A light beam 9 is emitted from a light source 4 to be collimated 5 and then, a part thereof is reflected with a half mirror 6 to be turned to a light beam 9a, the intensity of which is measured with a light intensity measuring device 7. On the other hand, the rest of the light beam 9 is transmitted through the half mirror 6 to be turned to an incident light beam 9b into a pericle 3. A part of the light beam 9b is reflected with the pericle 3 to be turned to a reflected light beam 10a, the intensity of which is measured with a light intensity measuring device 8. In this manner, a reflectance is obtained from the light intensities measured respectively with the light intensity measuring devices 7 and 8 with due consideration given to the wavelength of the light beam and the angle of incidence into the pericle 3 and finally, the transmission factor of the wavelength of an exposure light incident vertically into the pericle 3 is calculated. Otherwise, a method is available that the light beam transmitted through the pericle 3 is measured with a light intensity measuring device. |
