摘要 |
An illumination system for an interferometer combines a white-light source and a green source with a reflective green dichroic filter. When the green source alone is energized for PSI measurements, the output of the illumination system is green only. When a white-light output is desired for VSI measurements, both sources are energized and the intensity of the green light is judiciously calibrated to match the spectral band filtered out by the dichroic mirror. Therefore, the system can switch between green and white light simply by changing the selection of energized sources, without any mechanical switching and attendant delays and vibrations. Multiple narrowband sources may be combined with white light in a similar manner.
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