| 摘要 |
PURPOSE:To adjust easily the focus and the optical axis of a photometric objective lens by setting a sighting optical system in a photometric optical system and observing a sighting mark and a flowing part on occasion with naked eyes or a TV monitor. CONSTITUTION:Particles to be examined pass in a flowing part 2 in the center of a flow cell 1. Light L from a laser light source 3 is led to the flowing part 2 by an image forming lens system 4. Forward scattered light out of scattered light due to particles to be examined of light L passes a condenser lens 5 and is transmitted through a half mirror 6 and is condensed on a photodetector 7 to measure properties of particles to be examined. A part of forward scattered light reflected on the half mirror 6 is observed through the first focusing screen 8 and an eyepiece lens 9 by an observing eye E. The focusing screen 8 is arranged in the position optically equivalent to the photodetector 7 with the half mirror between them, and the sighting mark is entered on the focusing screen 8. The observer aligns the sighting mark on the focusing screen 8 and the flowing part 2 to see vividly the flowing part 2 on the focusing screen 8, thereby adjusting the focus and the optical axis of the photometric optical system for forward scattered light.
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