Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Reexamination Certificate
2001-07-20
2003-12-23
Allen, Stephone B. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
C313S542000
Reexamination Certificate
active
06667472
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a night vision device, and particularly to a night vision device which avoids problems caused by reflection of bright lights which may be in the field of view.
BACKGROUND OF THE INVENTION
Night vision devices are well known electro-optical devices which afford a user enhanced visibility in darkness. They find widespread application in the military, law enforcement, and security operations.
A night vision device typically includes an objective lens assembly, an image intensifier tube and an eyepiece or ocular. In operation, the objective lens assembly focuses low levels of light including infrared (IR) onto the image intensifier tube, which amplifies the light and transmits it to the eyepiece for viewing of an image. The image intensifier is typically comprised of a cathode for converting light including IR to electrons, a microchannel plate for multiplying the electrons, and a phosphor screen.
A problem occurs when bright light is either in or near the field of view. Such light may bounce back and forth between the image tube and objective lenses creating “ghost” like patterns. The stray light patterns are superimposed upon the image, obscuring the image and degrading the performance of the device.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to reduce stray light and “ghost” like patterns caused by bright lights in or near the field of view of a night vision device.
In accordance with a first aspect of the invention, the above object is accomplished by providing an image intensifier tube having a cathode window which bears an antireflection coating.
In accordance with a second aspect of the invention, the antireflection coating is disposed on a glass plate which is adhered to the cathode window.
In accordance with a further aspect of the invention, the antireflection coating may be employed directly on the cathode window.
In accordance with a still further aspect of the invention, a laser reflecting coating may be employed on the cathode window in addition to or instead of the antireflection coating, either disposed on a plate or on the cathode window itself.
REFERENCES:
patent: 4475059 (1984-10-01), Sink
patent: 5130527 (1992-07-01), Gramer et al.
patent: 5146076 (1992-09-01), Raverdy et al.
patent: 5301069 (1994-04-01), Wood et al.
patent: 6088165 (2000-07-01), Janeczko et al.
patent: 6201641 (2001-03-01), Filipovich
patent: 6288386 (2001-09-01), Bowen et al.
patent: 6472087 (2002-10-01), Otani et al.
patent: 6483231 (2002-11-01), Iosue
Janeczko Donald J.
Thomas Nils I.
Abramson Martin
Allen Stephone B.
Edell, Shapiro & Finnar
ITT Manufacturing Enterprises Inc.
LandOfFree
Night vision device with antireflection coating on cathode... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Night vision device with antireflection coating on cathode..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Night vision device with antireflection coating on cathode... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3122631