Radiant energy – Infrared-to-visible imaging
Reexamination Certificate
2002-01-29
2004-03-02
Gutierrez, Diego (Department: 2859)
Radiant energy
Infrared-to-visible imaging
C250S333000
Reexamination Certificate
active
06700123
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an object detection apparatus, and more specifically to an object detection apparatus having a light intensifier tube which includes a shutter electrode, and which finds usefulness in viewing objects in environments having on the one hand, low ambient light, or on the other hand, other conditions which prohibit the timely, and effective imaging of the objects.
DESCRIPTION OF THE PRIOR ART
The prior art is replete with numerous examples of prior art image intensifying devices which have been incorporated into devices such as night vision scopes, laser range finders and other similar devices which have been used in various civilian and military applications.
As a general matter, many of these devices have included a light intensifier tube which transforms electromagnetic radiation which may, in some cases, not be visibly perceivable by the human eye, and which may be in selected wavelengths such as infrared, ultraviolet, or x-ray, and convert this same electromagnetic radiation into a visible image which then may be utilized by an observer for various applications. Yet further, these same light intensifier tubes may be designed to take ambient, visibly discernable electromagnetic radiation, and thereafter amplify it to create a visibly perceivable image which may be used by an observer to see an object of interest under poor visibility conditions.
The prior art light intensifier tubes, as a general matter, normally include a photocathode; an image intensification system; an anode and a luminescent screen. In this regard the photocathode is operable to transform the electromagnetic radiation forming the original optical image into an electronic image. The image intensifying system in these prior art devices is operable to take the electronic image, amplify it and then transfer it to the luminescent screen, where this image is then converted into a visibly discernable image which may be perceived by the operator of same. In this arrangement, electromagnetic radiation originating from the object of interest, or from another source, upon impacting the photocathode causes a resulting emission of electrons in the form of a photocurrent from the surface of same. The resulting photoelectrons formed by this process are accelerated and focused by the light intensifier tube. The focused photoelectrons bombard the luminescent screen and cause it to luminesce. In order to focus the photoelectrons to produce good useable images, the various prior art devices have utilized magnetic fields of various types, and other electrostatic-type lenses which are located between the photocathode and the anode. The aforementioned lenses are operable to collect the electrons emitted from the photocathode surface into narrow beams which reproduce on the luminescent screen in a visibly discernible image which closely replicates or corresponds to the image projected on the photocathode.
While these earlier prior art light intensifier tubes have operated with varying degrees of success, numerous shortcomings in their individual designs have detracted from their usefulness.
For example it has been observed, that the optical resolution capacity of these earlier prior art light intensifier tubes was somewhat limited by aberrations in the electronic lenses employed with same. Still further, it was observed that it was quite difficult to reduce optical aberrations to allowable ranges by changing the resulting geometry of any of the electrodes employed in these assemblies. Consequently, in the decades following the development of these aforementioned prior art devices, sophisticated second and third generation light intensifier tubes were developed which included the use of assorted fiber-optical electrodes, and microchannel plates of various designs. While these so-called multiple-stage light intensifier tubes significantly increased the brightness of any resulting image, further difficulties remained with the use of such devices for imaging objects where other competing light sources might also be in the general vicinity of the object being observed. In this regard, other bright light sources in the vicinity of the object being viewed would often cause the resulting image provided to the observer to be completely unusable. This has been known as the so-called “Bloom Effect”. Various schemes and devices have been developed to reduce the bloom effect and this is shown more clearly in various prior art references such as U.S. Pat. Nos. 5,396,069 and 5,519,209 to name but a few.
As might be expected, while these various improvements have resulted in second and even third generation light intensifier tubes having improved performance characteristics, these improvements have significantly increased the difficulty in manufacturing same, and the resulting cost of the more recent light intensifier tubes when incorporated into various devices have placed them virtually out of reach for use in many industrial and other civilian applications. Consequently, their use has been confined, to a large degree, to mostly military and other law enforcement applications.
Accordingly, an object detection apparatus and accompanying light intensifier tube which achieves the benefits to be derived from the aforementioned technology, but which avoids the determents individually associated therewith, and which can be used in various civilian and other industrial applications to image objects of interest during reduced ambient lighting or other environmental conditions is the subject matter of the present invention.
SUMMARY OF THE INVENTION
A first aspect of the present invention relates to an object detection apparatus having a light intensifier tube which includes a photocathode; a luminescent screen disposed in spaced relation relative to the photocathode; a shutter electrode disposed intermediate the photocathode and the luminescent screen; and an anode located intermediate the shutter electrode and the luminescent screen.
Another aspect of the present invention relates to an object detection apparatus which includes a shutter electrode having an integral body which comprises a first cylindrical portion and a second cylindrical portion, each of the cylindrical portions having a predetermined diametral dimension, and wherein the first cylindrical portion is located adjacent the photocathode and wherein the diametral dimension of the first cylindrical portion is less than the diametral dimension of the second cylindrical portion.
Another aspect of the present invention relates to an object detection system which includes a light intensifier tube having a shutter electrode which has a first operational condition which permits electromagnetic radiation to be processed by the light intensifier tube, and a second operational condition which substantially prevents electromagnetic radiation from being processed by the light intensifier tube, and wherein the shutter electrode is placed in the first condition for a predetermined duration of time, and wherein the duration of time is adjustable.
Another aspect of the present invention relates to an object detection apparatus including a light intensifier tube which produces a visibly discernable light output from which information regarding the object of interest may be derived.
Yet a further aspect of the present invention relates to an object detection apparatus which includes a light intensifier tube having an adjustable shutter electrode, and wherein a charge couple device is provided and which is located in optical receiving relation relative to the visible light output provided by the light intensifier tube, and wherein the charge couple device produces an output signal from which information regarding the object of interest may be derived.
Another aspect of the present invention relates to an object detection apparatus which includes an operator display coupled in signal receiving relation relative to the electromagnetic radiation receiver, and which provides a visibly discernable image of the object of interest which may be viewed by the
Gaber Leonld
Morgovsky Marc
Musiel Michael J.
Naroditsky Dmitry
Voigt James R.
Cohen Amy R.
Gutierrez Diego
K. W. Muth Company
Wells St. John P.S.
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