| 摘要 |
A light intensity monitoring and adjusting apparatus for a light-fastness testing apparatus having a xenon lamp and a power source circuit for supplying power to the lamp. The monitoring and adjusting device has an optical fiber light guide having three bundles of optical fibers therein. One end is directed toward the xenon lamp for picking up the light emitted therefrom and the other end is connected to a light-receiving means including a plurality of three light-receiving elements, one for ultraviolet light, one for visible light, and one for infrared light. Each produces an electrical signal corresponding to the intensity of the light received. The apparatus has a source of reference voltage and a voltage comparator coupled to the source of reference voltage for comparing input voltages from the light-receiving elements with the reference voltage. A voltage adjusting means is coupled to the power source circuit for adjusting the voltage supplied to the lamp and is driven by the output of the voltage comparator to change the voltage supplied to the lamp to bring the intensity of the light produced by the lamp to a value corresponding to the light intensity value represented by the reference voltage, whereby the intensity of light in a spectrum emitted by the lamp can be kept constant for testing specimens for light-fastness under constant conditions. |
