| Popis: |
A deep UV projection system, capable of imaging lines and spaces of A 0.5 m width over a 14.5 mm diameter field has been developed. The system utilizes a single glass (fused silica) projection lens and a KrF excimer laser source at 248.4 nm wavelength. The fact that the lens has no chromatic correction imposes certain requirements on the laser source, such as the spectral bandwidth, wavelength stability and broad band background. The results of a study (theoretical and experimental) on how these laser characteristics affect the projection lens imaging are presented in this paper. We show the dependence of image contrast on laser bandwidth and wavelength shift, and the effect of injection locking efficiency on the size of printed lines and spaces. We also discuss the various approaches to laser line narrowing and some problems associated with a coherent light source. |
