Optical: systems and elements – Single channel simultaneously to or from plural channels – By partial reflection at beam splitting or combining surface
Patent
1993-11-12
1996-01-09
Epps, Georgia Y.
Optical: systems and elements
Single channel simultaneously to or from plural channels
By partial reflection at beam splitting or combining surface
348217, G01N 2164
Patent
active
054833795
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to color imaging in weak light using image intensifiers.
BACKGROUND OF THE INVENTION
Optical image intensifiers, e.g. of the microchannel plate type, are well-known and widely used for night vision use. A scene is projected by an optical system onto the input surface of an intensifier tube, and the resulting intensified image on the output surface may be perceived e.g. by an optical microscope system or a TV system. In order to obtain good viewing, the image tube is normally provided with a phosphor layer emitting in a greenish color, corresponding to the maximum light sensitivity of the human eye.
Due to the sensor construction in the human eye, with rods for night vision, void of color sensitivity, and cones for daylight and color vision, it is not generally realized that in fact, a natural scenery has just as much color by night as by day, as long as the available light is multicoloured, which is the case both for moonlight and for starlight, possibly with a different spectral distribution.
It is the general object for the invention to utilize this insight by obtaining a night vision/imaging system which admits of color perception of feebly lit scenes. Besides the obvious military use, such a system would be favorable e.g. for nature viewing and photographing at night or in caverns, hunting, for watchmen and on ships at night.
It is a further object to obtain color vision at night with the use of means which are not too expensive. Although optical image intensifiers nave been improved in recent years, with prices decreasing, they are still expensive and need electrical H.T. equipment, and the invention therefore envisages obtaining color vision using only one image intensifier, which is used in a multiplex system.
SUMMARY OF THE INVENTION
The present invention provides a device for obtaining a viewable image in color wherein a sole image intensifier is provided at its input side with an optical imaging system comprising a plurality of color filters, imaging a scene in color multiplex, and at its output side with means for combining the multiplexed output plurality of one-color images into a viewable color image. According to a first aspect of the invention, the multiplex is a time multiplex, such that the plurality of filters are used successively. In a particularly attractive embodiment thereof, a set of filters are switchingly introduced, e.g. on a revolving disc in the input imaging system, and a corresponding set of discs are arranged for filtering the image created on the output surface of the imaging tube. For occular viewing, the eye will be able to create a color image from the successive different color separated images, much as a multicolored sectored disc when seen rotated will look single-colored, white if the mixture is right. In this embodiment, the phosphor must have a sufficiently broad color spectrum, preferentially looking white. In the absence of output filtering, the output image is monochrome, since the intensifier tube is fundamentally monochrome.
With the time multiplex aspect, it is also possible to perceive the different images separately via a TV camera tube and make the combination subsequently. In that case, the phosphor does not have to have a broadband spectrum.
According to a second aspect of the invention, the multiplex is a space multiplex, where on the input surface of the intensifier tube is provided a plurality of color-filtered images simultaneously, so to say side-by-side. Such a system must have a plurality of ray-paths, each with its own color filter. In preferred embodiments, those ray-paths are obtained by means of a beam-splitter system, as a system with separate openings would create parallax. Systems with dichroic mirrors can be envisaged, but presently, a system is preferred where a mirror is cut up into a plurality of pieces, which are angled such as to create separate images on to the input surface of the image intensifier. The output images may be scanned by a TV camera tube, giving a host of pos
REFERENCES:
patent: 2548118 (1951-04-01), Morton
patent: 3589811 (1971-06-01), Berger
patent: 3720146 (1973-03-01), Yost
patent: 3812526 (1974-05-01), Tan
patent: 4652739 (1987-03-01), Sciamanda
patent: 4786813 (1988-11-01), Svanberg
patent: 4801212 (1989-01-01), Imura
patent: 5157548 (1992-10-01), Monnier
patent: 5162647 (1992-11-01), Field, Jr.
patent: 5214503 (1993-05-01), Chiu
patent: 5241170 (1993-08-01), Field, Jr.
Johansson Jonas
Svanberg Sune
Epps Georgia Y.
Mack Ricky
LandOfFree
Image registering in color at low light intensity does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Image registering in color at low light intensity, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image registering in color at low light intensity will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1306548