COLOUR CAST COMPENSATING FILTER FOR OPTICAL APPLIANCES WITH VIEWING AND PHOTOGRAPHIC BEAM PATHS

摘要

A colour cast compensating filter for optical appliances has an interference filter layer with the following composition (for a reference wavelength (lambda) = 500 nm): nG (glass dispersion disk) / 0.3019 H / 0.6179 L / 0.7495 H / (0.4910 L / 0.9722 H)5 0.9616 L / 2.0773 H / 0.4700 L / 0.6630 H / 1 (air). The low refraction material consists of MgF2 whereas the high refraction material consists of a substance constituted by the group ZrO2, Ta2O5, HfO2, a mixture of metal oxides and rare earth oxides. This interference filter layer allows the light intensity of a complex optical appliance with viewing and photographic beam paths for different wavelengths to be influenced in a defined manner, so that a colour-neutral photographic reproduction and viewing of the microscoped objects may be obtained. This interference filter layer is produced by high-vacuum vapour deposition. The glass substrate may have an index of refraction nG between 1.52 and 1.9. The angle of incidence is equal to (0 +- 10) .