To provide an automatic tilt angle compensator by the use of a free liquid level, and to provide a device for compensating for an optical axis to suppress the scattering of luminous flux transmitted through an optical member and to maintain high stability and precision.
This compensator includes a liquid sealed container 1 sealingly containing a transparent liquid 2 to form a free liquid level 3, a light projecting system 8 arranged to transmit outgoing luminous flux through the free liquid level 3, an incident window 4 for receiving the luminous flux from the light projecting system 8, and an emitting window 5 for emitting the luminous flux from the sealed container 1 after transmitted through the transparent liquid 2. The window 4 or the window 5 is inclined and is not immersed in liquid. In this case, even when liquid is attached to the window which is not immersed in liquid, the inclination of this window prevents retention of the liquid and suppresses scattering of the luminous flux.
TAKAHASHI TAKASHI
OTOMO FUMIO
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