Cassegrain Lens

This all-metal reflecting optics lens was originally designed as a long working distance, in-vacuum, on-axis lens yielding sub-micron diameter spot sizes for laser microprobe mass analysers. The Cassegrain design has zero chromatic aberration, so that any wavelength can be focused or viewed through the lens. The lens is constructed by polishing the reflective surfaces directly onto stainless-steel, which is normally then coated with aluminium and magnesium chloride to enhance ultra-violet reflection. However, alternative coatings for other wavelengths can be applied upon request. The all-metal construction means high power laser intensities can be used and also allows the structure to be baked for outgassing in an ultra-high vacuum environment.