Optical: systems and elements – Compound lens system – Telescope
Patent
1996-12-30
1998-01-27
Nguyen, Thong
Optical: systems and elements
Compound lens system
Telescope
359400, 359407, 359482, G02B 2300, G02B 2702
Patent
active
057127263
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to nighttime vision, that is to say the observation of a scene under very weak conditions of illumination provided for example by starlight or moonlight, and without additional lighting of the scene.
DISCUSSION OF THE BACKGROUND
Nighttime vision systems are designed to be carried in the hand or to allow hands-free use. In the latter case, the vision system is fixed to the user's face with the aid of a support mask fitted with straps or on a vehicle as is the case for example in respect of infrared periscopes of the type described for example in the GB Patent 918213.
Vision devices carried in the hand are principally intended for distant observation and incorporate an optical combination capable of multifold magnification of the observed field. On the other hand, nighttime vision systems of the hands-free type, intended for movement, vehicle driving or the carrying out of nighttime work, exhibit a magnification equal to one so as to offer natural conditions of vision. The invention is particularly, but not exclusively, intended for this type of application.
Nighttime vision systems are conventionally based on employing an image intensifier tube, including a photocathode serving as entrance surface, a microchannel electron transfer and multiplication system, and a phosphor screen serving as exit surface. A wide-aperture objective forms an image of the observed scene on the entrance surface, then the image is electronically intensified and finally restored on the phosphor screen so as to be observed through an eyepiece assembly.
Two-eyepiece vision is obtained by separating the flux exiting the tube into two eyepiece pathways with the aid of an optical splitter.
The need to fix night driving equipment to the head gives rise to the presence of significant ergonomic constraints. Thus, the mass of the equipment and its protuberant shape, owing to the alignment of the elements--objective, tube, eyepiece--on a viewing axis, give rise to a shift of the center of gravity of the head and modify its inertial characteristics, this causing problems of fatigue in the neck region. Moreover, the presence of this fragile and relatively long protuberance (conventionally between 100 and 170 mm) reduces the mobility of the user, especially in respect of movements under difficult conditions or in respect of vehicle driving.
To solve this problem, there is known from U.S. Pat. No. 4,826,302 a bent optical system in which the objective and the intensifier are oriented along a horizontal axis perpendicular to the viewing axis. The dimension of the equipment along the viewing axis is thereby reduced and the center of gravity of the assembly is shifted towards the observer. However, this design requires that a significant number of reflections be employed on each of the optical pathways.
SUMMARY OF THE INVENTION
The invention aims to obtain even more compact nighttime vision binoculars employing a reduced number of optical elements.
To achieve these objectives, the invention is based on setting up a principal optical pathway inclined with respect to the plane of the optical axes of the eyepieces and culminating in a first eyepiece pathway onto which will be grafted a second eyepiece pathway.
More precisely, the subject of the invention is binoculars for nighttime vision including an entrance objective conjugate with a light-intensifier tube for forming an image of a scene from light flux originating from the scene along a viewing axis, an intensified image next being transmitted by an image transport and by an optical splitter which partially transmits the flux by transmission and reflection respectively on a first pathway to a first eyepiece and on a second pathway, which is bent twice, to a second eyepiece, the eyepieces having axes parallel to the viewing axis, characterized in that the tube and the image transport are aligned so as to constitute a principal optical pathway along a principal optical axis lying in a plane perpendicular to the viewin
REFERENCES:
patent: 2426207 (1947-08-01), Handy
patent: 2537962 (1951-01-01), Brown
patent: 4383741 (1983-05-01), Vogl et al.
patent: 4653879 (1987-03-01), Filipovich
patent: 4826302 (1989-05-01), Apsenius
Coumert Bruno
Espie Jean-Luc
Angenieux SA
Nguyen Thong
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