| 摘要 |
A light source is arranged with a light sensing device in such a way that the sensing device receives transmitted light for a translucent medium or reflected light for an opaque medium. The reading of the sensor is stored, then the same source and sensing device are moved over a reference medium whose absorptivity varies unidirectionally. A comparator compares the reading of the sensor with the stored reading and indicates when they are equal. The relative position of the reference and sensor indicates the absorptivity of the medium. One embodiment uses multiple devices and filters to determine composite color.
|
