US 5,220,164 AGranted

Integrated imaging and ranging lidar receiver with ranging information pickoff circuit

AssigneeGeneral Atomics

InventorsAlbert J. Lieber, Peter K. Trost

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Abstract

An integrated LIDAR receiver includes a single detection element to provide both imaging and ranging functions. The single detection element includes an opaque photocathode, a microchannel plate (MCP) electron multiplier, and a phosphor coated anode covered with a metalized layer. The metalized layer on the phosphor anode allows electrons striking the anode to be detected as a prompt electrical current. The prompt electrical current is detected through a transformer that couples the anode to a power supply. The power supply biases the anode relative to the MCP and photocathode such that the MCP is grounded. The use of a transformer allows the prompt anode current to be detected without having to ground the anode, thereby simplifying the power supply circuitry. The detection of the prompt electrical current provides a first output signal useful for ranging information. Visible light (photons) is also output from the anode in response to electrons striking the phosphor in the anode, and is used to provide an intensified image of a scene. The visible light may thereafter be detected by an imaging sensor, such as a CCD camera.

Claims22

Dependent claims

An integrated LIDAR receiver comprising:

an image intensifier having an opaque cathode;
an anode spaced apart from the cathode;
a microchannel plate (MCP) electron multiplier positioned intermediate the cathode and anode;
and a phosphor film deposited on a fiber optic substrate on said anode, said phosphor film being coated with a metalized layer;
a transformer having a primary winding and secondary winding;
power supply means for selectively applying a first voltage potential between said MCP and said anode through the primary winding of said transformer, with said anode being maintained at a positive potential relative to said MCP electron multiplier, and for selectively applying a second voltage potential between said MCP electron multiplier and said cathode, with said cathode being maintained at a negative potential relative to said MCP;
and
detection means coupled to the secondary winding of said transformer for detecting pulses of electrical current occurring at said metalized layer;
said pulses of electrical current occurring as a result of optical pulses striking said cathode, said optical pulses striking said cathode causing the emission of electrons, which electrons are multiplied by said MCP electron multiplier and accelerated towards said anode, with a fraction of the electrons striking said anode passing through said metalized film into the phosphor film, causing photons to be emitted in proportion to the energy of the electrons, said photons passing through said fiber optic substrate, and with a remaining fraction of the electrons striking said anode serving as a prompt electrical current pulse within said metalized layer, which prompt electrical current pulse induces a corresponding electrical current pulse in the secondary winding of said transformer, which corresponding electrical current pulse signals a precise time when the optical pulses strike said cathode.

6 more elements

A LIDAR system for providing ranging and imaging information relative to a target, said LIDAR system including:

(1) means for generating and directing a pulse of radiant energy having a known wavelength towards said target in response to a trigger signal;
(2) a integrated LIDAR receiver for receiving radiant energy of said known wavelength reflected from said target, said integrated LIDAR receiver comprising:
(a) a cathode spaced apart from an anode, electrons being emitted by said cathode in response to said cathode being impinged by radiant energy reflected from said target;
(b) electron multiplier means positioned intermediate the cathode and anode for receiving the electrons emitted from the cathode, and emitting a larger number of electrons than received, and
(c) said anode comprising a first layer of a first selected material overlaying a fiber optic substrate, and a second layer of a second selected material overlaying said first layer;
a fraction of the electrons striking said anode passing through said second layer and being converted to photons in said first layer, said photons thereafter being detectable through said fiber optic substrate;
and a remaining fraction of the electrons striking said anode remaining in said second layer and being detectable as a prompt anode current;
(3) a transformer having a primary winding and a secondary winding;
(4) power supply means for selectively applying a first voltage potential between said MCP electron multiplier and said anode of said LIDAR receiver through said primary winding of said transformer, and for selectively applying a second voltage potential between said MCP and said cathode;
said second voltage potential when of the proper polarity causing electrons emitted by said cathode to be accelerated towards said MCP electron multiplier, and said first voltage potential causing electrons emitted by said MCP electron multiplier to be accelerated towards said anode with a prescribed energy;
(5) detection means coupled to the secondary winding of said transformer for detecting the occurrence of said prompt anode current;
(6) timing means for measuring the elapsed time between said trigger signal and the detection of said prompt anode current;
(7) an image sensor coupled to said fiber optic substrate for generating an image signal responsive to photons impinging said image sensor through said fiber optic substrate;
and
(8) processing means for generating said trigger signal, processing said image signal, and computing a range indication from the elapsed time measured by said timing means, whereby both image and range information are provided relative to said target by detecting radiant energy of said known wavelength reflected from said target through said integrated LIDAR receiver.

12 more elements

A method of determining both image and range information relative to a target using a single LIDAR detector, said LIDAR detector including a cathode spaced apart from an anode, with electrons being emitted by the cathode in response to the cathode being impinged by radiant energy reflected from said target;

and with said anode including a phosphor layer covered with a metalized layer, said method comprising the steps of:
(a) generating a pulse of radiant energy having a known wavelength and directing said radiant energy pulse at said target;
(b) receiving radiant energy reflected from said target of said known wavelength at the cathode of said LIDAR receiver;
(c) biasing said anode relative to said cathode of said LIDAR receiver such that electrons emitted from said cathode in response to the radiant energy received in step (b) are accelerated towards said anode with a prescribed energy, said prescribed energy being selected such that a fraction of the electrons striking said anode pass through said metalized layer into said phosphor layer and cause photons to be emitted, and a remaining fraction of the electrons striking said anode remain in said metalized layer and are detectable as a prompt anode current;
(d) detecting the photons generated in said phosphor layer and producing an image signal therefrom;
(e) detecting the prompt anode current in said metalized layer;
(f) measuring the elapsed time between the generation of the radiant energy pulse in step (a) and the detection of the prompt anode current in step (e);
and
(g) calculating the distance to the target based upon the elapsed time measurement of step (f).

6 more elements

Dependencies are inferred from the claim text.