Optical instrument for observation
AssigneeFuji Photo Optical Co., Ltd.
InventorYukiko Nagatoshi
Life of this patent
Estimating the term…
Abstract
An optical instrument for observation includes, in order from the object side, an objective lens system having positive refractive power, an erecting optical system, and an ocular lens system having positive refractive power. When an anti-vibration mechanism is used to maintain the erecting prism at an orientation in space that is stabilized so as to prevent image degradation due to vibrations of the optical instrument for observation, the erecting prism is constructed to satisfy specified conditions so that ghost light is not generated and so that the optical instrument for observation may be compact.
Claims7
An optical instrument for observation comprising, in order from the object side:
- an objective lens system having positive refractive power;
- an erecting optical system;
- and
- an ocular lens system having positive refractive power;
- wherein
- an anti-vibration mechanism is used to maintain the erecting prism at an orientation in space that is stabilized so as to prevent image degradation due to vibrations of the optical instrument for observation;
- and
- the erecting optical system is an erecting prism that is constructed so as to satisfy the following Condition (1):
- 0.25<L/fo−sin ω<0.5 Condition (1)
- where
- L is the distance from the lens element surface nearest the object side of the objective lens system to the erecting prism,
- fo is the focal length of the objective lens system, and
- ω is the maximum angle of rotation of the erecting prism relative to the optical axis of the optical instrument for observation in order to maintain the spatial orientation of the erecting prism substantially constant in space when correcting for sudden changes in orientation of the optical axis.
An optical instrument for observation that comprises, in order from the object side:
- an objective lens system of positive refractive power;
- an erecting prism;
- and
- an ocular lens of positive refractive power;
- wherein said erecting prism includes, in order from the object side, a first prism and a second prism, and the following Conditions (2) and (3) are satisfied
- θ≧47° Condition (2)np1≧1.6 Condition (3)
- where
- θ is the apex angle of the first prism as measured between the first incident surface of light entering the prism and the next surface the light is incident upon;
- and
- np1 is the index of refraction of the first prism.
Dependencies are inferred from the claim text.