Optical: systems and elements – Compound lens system – Telescope
Reexamination Certificate
1999-07-06
2001-08-07
Nguyen, Thong (Department: 2872)
Optical: systems and elements
Compound lens system
Telescope
C359S377000, C359S407000
Reexamination Certificate
active
06271964
ABSTRACT:
BACKGROUND OF TEE INVENTION
1. Field of the Invention
The present invention relates to a close-up attachment lens which is attached to a front end (object side) of a binocular and which is located in front of a pair of objective lenses thereof to enlarge an image of an finite distance object.
2. Description of the Related Art
In a monocular telescope or the like, a close-up attachment which can be attached to a front portion of an objective lens of the telescope and permits a user to view an enlarged image of an object at a close proximity, is known in the art. However, no such attachment for a binocular is known.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a close-up attachment lens for a binocular.
A binocular is usually designed for viewing distant objects, therefore, if two close-up attachment lenses are attached to the front (object side) of each objective lens system of a binocular, objects at a close proximity cannot be viewed through both lenses as a single image, or fatigue of the viewer's eyes may be caused by the viewer attempting to view a double image as a single image. This is because rays of light emitted from the same object point which are incident upon the pair of close-up lens groups and the pair of objective lenses of the binocular, and emitted from the pair of eyepieces of the binocular, are not parallel. In such a case, the vergence of the objective lens systems can (in theory) be adjusted so as to coincide. For example, the optical axes of the close-up lens systems can be decentered with respect to the optical axes of the objective long systems of the binocular, or a prism can be provided at an appropriate position within the optical path thereof so that the lines of sight can be bent inwards. However, such adjusting methods require extremely high precision, which is difficult to achieve; and even if achieved, there is a tendency for error to occur due to shock etc. For the above-mentioned reasons, the detachable close-up attachment lens of the present invention is not directed towards the attachment thereof to each individual objective lens system of a binocular.
It is another object of the present invention to provide a close-up attachment lens for a binocular in which no complex adjustment of the optical axis is necessary, and where there is no tendency for the optical axis to deviate due to shock etc.
To achieve the objects mentioned above, according to the present invention, there is provided a close-up attachment lens for a binocular, which is detachably attached on the object side of a pair of objective lenses of the binocular, including: a close-up lens group of a single optical system of positive power, the close-up lens group being located on the object side of the pair of the objective lenses of the binocular, so that the close-up lens group covers the pair of objective lenses and has an optical axis parallel with, and spaced from, optical axes of the objective lenses at an equal distance, and a pair of aperture stops, the aperture stops being located in front of the corresponding objective lenses of the binocular when the close-up attachment lens is attached to the binocular.
Preferably, the pair of aperture stops are provided behind the close-up lens group.
Preferably, the diameter of the aperture stops is set to be smaller than an effective aperture of the objective lenses of the binocular.
At least one reflection mirror can be provided, the reflection mirror being located in front of the objective lenses of the binocular when the close-up lens is attached to the binocular.
Preferably, the reflection mirror is provided behind the close-up lens group.
A pair of first reflection mirrors can also be provided behind the close-up lens group, corresponding to the objective lenses of the binocular to split, and deflect outward, light transmitted through the close-up lens group and a pair of second reflection mirrors to reflect the rays of light reflected by the first reflection mirrors toward the corresponding objective lenses of the binocular.
Preferably, a lighting optical system is also provided.
Preferably, the lighting optical system is provided behind the close-up lens system.
Preferably, the lighting optical system gathers light rays at the proximity of the object point via the refractive function of the close-up optical system.
Preferably, the light optical system includes a curved reflection mirror which reflects light rays toward the object side, wherein the lighting optical system has an optical axis which is parallel with the optical axis of the close-up lens group.
Preferably, the curved reflection mirror is a parabolic mirror.
Preferably, the close-up lens group includes a negative lens element and a positive lens element.
Preferably, the negative lens element and the positive lens element are arranged in this order from the object side.
The close-up lens group can include a negative lens element and two positive lens elements.
The close-up lens group can include negative lens element, a positive lens element, and another positive lens element, in this order from the object side. Preferably, the two positive lens elements in the close-up lens group are identical.
Preferably, the close-up lens group includes a cemented lens.
Preferably, the binocular is provided with a pair of ocular lens system corresponding to the pair of the objective optical systems, wherein the distance between the optical axes of the objective lenses is smaller than the distance between optical axes of the ocular optical systems.
The close-up attachment lens according to the present invention can be applied to any type of binocular. The close-up attachment lens can be particularly advantageously used with a binocular in which the distance between the optical axes of the objective lenses is smaller than the distance between the optical axes of the eyepieces, since the diameter of the close-up lens group can be reduced.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 10-188763 (filed on Jul. 3, 1998) which is expressly incorporated herein by reference in its entirety.
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Asahi Kogaku Kogyo Kabushiki Kaisha
Greenblum & Bernstein P.L.C.
Nguyen Thong
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