Methods and apparatus for providing wide range exposure control for image intensifier cameras
First Claim
1. An image intensifier camera, comprising:
- (a) image intensifier means having an adjustable gain;
(b) means for selectively attenuating light input to said camera;
(c) means for focusing the selectively attenuated light input onto said image intensifier means;
(d) image sensor means for integrating light output by said image intensifier means over a predetermined time interval, whereby said image sensor means generates an integrated light output signal; and
(e) automatic exposure control means for extending the dynamic range of said camera by controlling the gain of said image intensifier means, selectively gating said image intensifier means on and off, and controlling said means for selectively attenuating light, all in response to said integrated light output signal, wherein to adjust for steadily increasing light from an object under observation, said automatic exposure control means is operative to first adjust the gain of said image intensifier means, then control the gating of said image intensifier means and finally control said means for selectively attenuating light, and to adjust for steadily decreasing light from the object under observation, said automatic exposure control means is operative to first control said means for selectively attenuating light, then control the gating of said image intensifier means and finally adjust the gain of said image intensifier means.
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Accused Products
Abstract
The dynamic range of an image intensifier camera may be extended by using an automatic exposure control system which, in response to imager output (for example, the output of a charge coupled device (CCD) imager included in a solid state image intensifier camera), (a) generates a first control signal that controls the gain of the I2 Tube itself; (b) generates a second control signal for selectively gating the I2 Tube on or off; and (c) generates a third control signal for controlling a light attenuator that, according to a preferred embodiment of the invention, is included in the camera. The automatic exposure control system contemplated by the invention has a control range in excess of 1010 ×; takes a measurement of the exposure from an imager (again, for example, a CCD sensor) for comparison to a desired setpoint; the measurement used may be a peak, an average or some weighted function and the automatic exposure control logic then adjusts, in order, the I2 Tube gain, the I2 Tube gating and the light attenuator (using the aforementioned first, second and third control signals), to adjust for steadily increasing light from the object under observation. In addition to automatic exposure control systems per se, the invention is also directed to camera systems which incorporate such automatic exposure control systems and to methods for realizing the automatic exposure control systems of the type described hereinafter.
34 Citations
44 Claims
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1. An image intensifier camera, comprising:
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(a) image intensifier means having an adjustable gain; (b) means for selectively attenuating light input to said camera; (c) means for focusing the selectively attenuated light input onto said image intensifier means; (d) image sensor means for integrating light output by said image intensifier means over a predetermined time interval, whereby said image sensor means generates an integrated light output signal; and (e) automatic exposure control means for extending the dynamic range of said camera by controlling the gain of said image intensifier means, selectively gating said image intensifier means on and off, and controlling said means for selectively attenuating light, all in response to said integrated light output signal, wherein to adjust for steadily increasing light from an object under observation, said automatic exposure control means is operative to first adjust the gain of said image intensifier means, then control the gating of said image intensifier means and finally control said means for selectively attenuating light, and to adjust for steadily decreasing light from the object under observation, said automatic exposure control means is operative to first control said means for selectively attenuating light, then control the gating of said image intensifier means and finally adjust the gain of said image intensifier means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An automatic exposure control system for extending the dynamic range of an image intensifier camera, wherein said camera includes image intensifier means having an adjustable gain, means for selectively attenuating light input to said camera, means for focusing the selectively attenuated light input onto said image intensifier means, and image sensor means for integrating light output by said image intensifier means over a predetermined time interval, whereby said image sensor means generates an integrated light output signal, comprising:
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(a) first controller means for controlling the gain of said image intensifier means; (b) means for selectively gating said image intensifier means on and off; and (c) second controller means for controlling said means for selectively attenuating light, wherein said first controller means, said means for selectively gating and said second controller means are all operated in response to the magnitude of said integrated light output signal, wherein to adjust for steadily increasing light from an object under observation, said automatic exposure control means is operative to first adjust the gain of said image intensifier means, then control the gating of said image intensifier means and finally control said means for selectively attenuating light, and to adjust for steadily decreasing light from the object under observation, said automatic exposure control means is operative to first control said means for selectively attenuating light, then control the gating of said image intensifier means and finally adjust the gain of said image intensifier means. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. An image intensifier camera, comprising:
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(a) an image intensifier tube (I2 Tube) having an adjustable gain which may be varied by adjusting Micro Channel Plate (MCP) voltage of the I2 Tube; (b) means for selectively attenuating light input to said camera; (c) means for focusing the selectively attenuated light input onto said I2 Tube; (d) image sensor means for integrating light output by said I2 Tube over a predetermined time interval, whereby said image sensor means generates an integrated light output signal; and (e) automatic exposure control means for extending the dynamic range of said camera by adjusting said Micro Channel Plate (MCP) voltage to thereby control the gain of said I2 Tube, selectively gating said I2 Tube on and off, and controlling said means for selectively attenuating light, all in response to the amplitude of said integrated light output signal, wherein to adjust for steadily increasing light from an object under observation, said automatic exposure control means is operative to first adjust the gain of said image intensifier means, then control the gating of said image intensifier means and finally control said means for selectively attenuating light, and to adjust for steadily decreasing light from the object under observation, said automatic exposure control means is operative to first control said means for selectively attenuating light, then control the gating of said image intensifier means and finally adjust the gain of said image intensifier means. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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34. An automatic exposure control system for extending the dynamic range of an image intensifier camera, wherein said camera includes an image intensifier tube (I2 Tube) having an adjustable gain which may be varied by adjusting Micro Channel Plate (MCP) voltage of the I2 Tube, means for selectively attenuating light input to said camera, means for focusing the selectively attenuated light input onto said I2 Tube, and image sensor means for integrating light output by said I2 Tube over a predetermined time interval, whereby said image sensor means generates an integrated light output signal, comprising:
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(a) means for generating a first control signal that controls the gain of the I2 Tube; (b) means for generating a second control signal for selectively gating the I2 Tube on or off; and (c) means for generating a third control signal for controlling said means for selectively attenuating light, wherein to adjust for steadily increasing light from an object under observation, said automatic exposure control means is operative to first adjust the gain of said image intensifier means, then control the gating of said image intensifier means and finally control said means for selectively attenuating light, and to adjust for steadily decreasing light from the object under observation, said automatic exposure control means is operative to first control said means for selectively attenuating light, then control the gating of said image intensifier means and finally adjust the gain of said image intensifier means. - View Dependent Claims (35, 36, 37, 38, 39)
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40. A method for extending the dynamic range of an image intensifier camera, wherein said camera includes image intensifier means having an adjustable gain, means for selectively attenuating light inputs to said camera, means for focusing the selectively attenuated light input onto said image intensifier means automatic exposure control means, and image sensor means for integrating light output by said image intensifier means over a predetermined time interval, whereby said image sensor means generates an integrated light output signal, comprising the steps of:
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(a) controlling the gain of said image intensifier means utilizing first controller means; (b) selectively gating said image intensifier means on and off; and (c) controlling said means for selectively attenuating light utilizing second controller means wherein said first controller means, said means for selectively gating and said second controller means are all operated in response to the magnitude of said integrated light output signal, wherein to adjust for steadily increasing light from an object under observation, said automatic exposure control means is operative to first adjust the gain of said image intensifier means, then control the gating of said image intensifier means and finally control said means for selectively attenuating light, and to adjust for steadily decreasing light from the object under observation, said automatic exposure control means is operative to first control said means for selectively attenuating light, then control the gating of said image intensifier means and finally adjust the gain of said image intensifier means. - View Dependent Claims (41, 42, 43, 44)
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Specification