Multispectral light detection system

Abstract

A multispectrum light detection system for controlling exposure time of a photoresist coated substrate in a projection aligner-printer machine wherein the relatively narrow spectral responsivity characteristics of a selected photoresist is matched to the wider spectrum inherent in the output flux of a combined light source and optical system. A representative sample of the system's wide spectrum output flux is divided into three or more narrower spectral bands each of which is measured by its own detector that provides an electrical signal proportional to the radiant flux intensity within that band. The resultant electrical signals from the separate spectral bands are weighted and combined in a summing amplifier to form a composite exposure control signal. Means are provided to adjust the contribution of each electrical signal to the combined control signal in accordance with known spectral response characteristics of the photoresist.

Dependencies are inferred from the claim text.