An electron beam pattern generator comprises a laser beam generator to generate a laser beam. A photocathode receives the laser beam and generates one or more electron beams. The photocathode comprises cesium halide material, such as for example, cesium bromide or iodide. The cesium halide material may have a decreased workfunction that allows efficient operation at a wavelength of the laser beam of at least about 200 nm. Electron optics are provided to focus the electron beams onto a substrate that is supported on a substrate support.