Optics: measuring and testing – Range or remote distance finding – With photodetection
Reexamination Certificate
1998-05-26
2001-11-13
Buczinski, Stephen C. (Department: 3662)
Optics: measuring and testing
Range or remote distance finding
With photodetection
C396S089000, C396S139000
Reexamination Certificate
active
06317199
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an indicator for an optical instrument, for example, an indicator applied to a surveying instrument such as an auto-level or a transit instrument having a telephotographic system.
2. Description of the Related Art
A surveying instrument such as an auto-level or a transit instrument is basically provided with a collimating telescope, a level, and scales for measuring a rotative angle (an azimuth angle) or an elevational angle. A typical auto-level collimating telescope is provided, in order from an object side, with an objective lens group, a focusing lens group, a horizontal compensation and erecting optical system, and an eyepiece lens group. The position of the focusing lens is adjusted according to the distance from the object, so that an image of the object may be formed on a reticle (focusing plate). The operator may thus observe the image superimposed on the reticle via the eyepiece.
Surveying instruments, such as an auto-level, did not have a distance measuring apparatus that could indicate the distance to an object, for example to a staff. In particular, although the auto-level may preferably be located at the equal distance position from two measuring points, the auto-level has no function to measure the distance. Therefore in the prior art, the position of the auto-level has usually been decided according to experience and intuition of the operator. Accordingly, it would be convenient if the distance to the measuring point could be made known to the operator.
A collimating telescope of surveying instrument in which an automatic focusing apparatus is provided is well known. According to a conventional automatic focusing apparatus, even if accurate focusing is not carried out, as long as the defocus is little enough so that the operator may feel as though the image is focused, the focusing operation would be stopped. However, the measuring of the object distance with the existence of such a defocus may result in a large object distance error.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an indicator of an optical instrument to carry out focusing by moving a focusing lens group, in which an object distance observed by an operator can be indicated to the operator.
It is another object of the present invention to provide an automatic focusing apparatus which can detect the object distance more accurately.
Since the distance of an object being viewed through a survey instrument having a collimating telescope is conventionally determined as being the distance from the objective lens group of the collimating telescope to the focusing plate, if the focal length of the objective lens group and the focusing lens group, and the distance between the objective lens group and the focusing lens group are known, the object distance can be readily determined. Namely, if the amount of movement of the focusing lens group from a reference position (for example, the position of a focusing lens group in infinity) is detected, the distance to the object can be obtained. Therefore, to achieve the object mentioned above, according to the present invention, there is provided an indicator for an optical instrument including an observational optical system to observe an image formed by an objective optical system having a focusing lens group, composing of: a lens position detecting device to detect a position of the focusing lens group, a distance detecting device to obtain an object distance according to a position of the focusing lens group detected by the lens position detecting device, and an inside-visual-field display device to display an object distance in a visual field of the observational optical system detected by the distance detecting device.
Further, according to an invention as claimed in claim
13
, there is provided an indicator for an optical instrument including an observational optical system to observe an image formed on a predetermined focal plane by an objective optical system having a focusing lens group, composing of: a split optical system positioned between the objective optical system and the observational optical system, a focusing detecting device to detect a defocus amount at a position equivalent to the focal plane by receiving light divided by the split optical system, a lens driving device to drive the focusing lens group according to a defocus amount detected by the focusing detecting device so that the defocus amount becomes a smallest value, a lens position detecting device to detect a position of the focusing lens group; an object distance detecting device to detect an object distance according to a position of the focusing lens group detected by the lens position detecting device and according to the defocus amount; and an inside-visual-field display device to display an object distance in a visual field of the observational optical system detected by the object distance detecting device.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 09-133844 (filed on May 23, 1997) which is expressly incorporated herein by reference in its entirety.
REFERENCES:
patent: 4113381 (1978-09-01), Epstein
patent: 5231441 (1993-07-01), Hata
patent: 5258802 (1993-11-01), Arimoto et al.
patent: 5315341 (1994-05-01), Hibbard
patent: 7-52626 (1995-11-01), None
Asahi Kogaku Kogyo Kabushiki Kaisha
Buczinski Stephen C.
Greenblum & Bernstein P.L.C.
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