| 摘要 |
A low power microscope is optically coupled by a partial reflector to the output light beam passed through a region of a photometer containing a sample of material being investigated. The microscope provides an observable image encompassing the region and is adjustable to bring various portions of the region into sharp focus. The reflector is carried on a base coupled to the end of the microscope so that extreme positions of the latter cause the base to move between a lowered position in which the reflector intercepts a portion of the output light beam and a raised position out of the path of the light beam. In the raised position a portion of the base serves to block the optical path through the viewer to thereby exclude stray light.
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