| 摘要 |
A multi-pass spectrometer. Light from a source (4) is expanded and collimated with a collimating optic (10) into a collimated beam. The collimated beam illuminates a dispersing optic such as a grating (12) from which light is reflected back toward the collimating optic. A transmitting-reflecting optic (20) is positioned across the collimated beam to cause at least two reflections of at least a portion of the collimated beam from the dispersing optic. A photometer (18) measures the double dispersed beam at a range of spacial locations in order to determine spectral characteristics of the light from the light source. In a preferred embodiment, a partially reflecting mirror (20) is positioned between the grating (12) and a collimated optic (10). This mirror is positioned at an angle slightly different from 90 degrees so that a portion of the light reflected from the dispersing optic is reflected back toward the dispersing optic at a slightly different range of angles. A portion of this second reflected beam is dispersed again and reflected at a different range of angles by the dispersing optic. A portion of this second reflected beam transmits the partially reflecting mirror and may be focused, and the intensity of the light at spatially distinct positions are measured by a photometer to access spectral characteristics of the light source. In a second preferred embodiment, the light from a third reflected beam is measured.
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