Light amplifier device having an ion and low energy electron trapping means

Claim 2

An image intensifier which includes: front end means for receiving an optical image; a photocathode for receiving said optical image and generating electrons representative of said image; a target electrode, said target electrode including a layer of metal covering a back side of said target electrode; an electron multiplying microchannel plate located between said target electrode and said photocathode with said microchannel plate having a front side facing said photocathode and a back side facing said back side of said target electrode, said microchannel plate spaced by a first predetermined distance from said photocathode and spaced by a second predetermined distance from said target electrode, said second predetermined distance being at least 1.5 times greater than said first predetermined distance; a very thin substantially optically transparent non-selfsupporting layer of material having a thickness in the range of 50 A. to 400 A. situated upon and covering the front side of said microchannel plate for trapping ions and low energy level electrons and passing other electrons and incidental light to thereby increase the contrast resolution capability of the tube and the operational life thereof; means for applying a first predetermined voltage between said photocathode and said microchannel plate; means for applying a second predetermined voltage between said microchannel plate and said target electrode; said second predetermined voltage being more than twice as large as said first predetermined voltage; and means for appying a third voltage between the front and rear ends of said microchannel plate.

Claim 3

The invention as defined in claim 1 wherein said material comprises a specific gravity in the range of 1.0 to 4.0.

Claim 4

The invention as defined in claim 2 wherein said material comprises a metal.

Claim 5

The invention as defined in claim 3 wherein said metal comprises aluminum.

Claim 6

The invention as defined in claim 2 wherein said material consists of a member selected from the group comprising aluminum, aluminum oxide, boron, beryllium, boron carbide, silicon oxide, silicon dioxide, magnesium oxide, and magnesium fluoride.

Claim 7

The invention as defined in claim 2 wherein said material possesses a coefficient of secondary emission greater than 3.0 at a potential of 400 volts.

Claim 8

The invention as defined in claim 1 wherein said first predetermined distance is in the range of 0.005-inches to 0.020-inches and wherein said second predetermined distance is in the range of 0.030-inches to 0.050-inches, and wherein said first predetermined voltage is in the range of 400 to 1,000 volts and wherein said second predetermined voltage is in the range of 3, 000 volts to 8,000 volts.

Claim 9

A light amplifier which comprises: a phosphor display screen of a predetermined area; a metal backing layer covering the backside of said phosphor display screen; a photocathode spaced from said display screen for emitting electrons in response to incident light; a microchannel plate type electron multiplying element located between said display screen and said photocathode, said electron multiplying element having a front input side facing said photocathode and a rear output side facing said display screen, said electron multiplying element being spaced from said photocathode by a first predetermined distance within the range of 0.005-inches to 0.020-inches and being spaced from said display screen by a second predetermined distance greater than said first predetermined distance in the range of 0.030-inches to 0.050-inches; a thin non-self-supporting substantially optically transparent layer of electrically conductive material coupled to and covering the front end of said microchannel plate; means for establishing a first voltage difference between said photocathode and said front end of said electron multiplying element to accelerate electrons in a direction from said photocathode toward said electron multiplying element; means for establishing a second voltage difference between the ends of said electron multiplying element to create an electric field for accelerating electrons in a direction from the front to the back end thereof; and means for establishing a third voltage difference between the rear end of said electron multiplying element and said display screen for accelerating electrons toward said target, said third voltage difference being at least twice as large as said first voltage difference.

Claim 10

A light amplifier which comprises: a phosphor display screen of a predetermined area; a metal backing layer covering the backside of said phosphor display screen; a photocathode spaced from said display screen for emitting electrons in response to incident light; a microchannel plate type electron multiplying element located between said display screen and said photocathode, said electron multiplying element having a front input side facing said photocathode and a rear output side facing said display screen, said electron multiplying element being spaced from said photocathode by a first predetermined distance within the range of 0.005-inches to 0.020-inches and being spaced from said display screen by a second predetermined distance greater than said first predetermined distance in the range of 0.030-inches to 0.050-inches; a thin non-self-supporting substantially optically transparent layer of electrically conductive material coupled to and covering the front end of said microchannel plate; means for establishing a first voltage difference between said photocathode and said front end of said electron multiplying element to accelerate electrons in a direction from said photocathode toward said electron multiplying element; means for establishing a second voltage difference between the ends of said electron multiplying element to create an electric field for accelerating electrons in a direction from the front to the back end thereof; and means for establishing a third voltage difference between the rear end of said electron multiplying element and said display screen for accelerating electrons toward said target, said third voltage difference being at least twice as large as said first voltage difference.

Claim 11

The invention as defined in claim 8 wherein said first distance comprises approximately 0.012-inches and wherein said second distance comprises approximately 0.038-inches.

Claim 12

The invention as defined in claim 9 wherein said first voltage comprises approximately 600 volts and wherein said third voltage comprises approximately 5,000 volts.

Claim 13

The invention as defined in claim 10 wherein said electrically conductive material comprises aluminum.

Claim 14

An image intensifier comprising: front end means for receiving an optical image; a photocathode; means for directing said optical image upon said photocathode; a target electrode, said target electrode including a metal backing layer; a microchannel plate, said microchannel plate located between and spaced from said photocathode and target electrode with the distance between said plate and said photocathode being less than the distance between said plate and said target electrode, said microchannel plate having a front end facing said photocathode and a rear end facing said target electrode; first voltage supply means for establishing a low potential difference in the range of 400 to 1,000 volts between said photocathode and said microchannel plate to accelerate electrons toward said microchannel plate; second voltage supply means for establishing a high potential difference in the range of 3,000 to 8,000 volts between said microchannel plate and said target electrode to accelerate electrons toward said target electrode; third voltage supply means for proviDing a potential difference between the front and back ends of said microchannel plate to cause electrons to travel from the front end to the back end of said microchannel plate; and a very thin non-self-supporting layer of electrically conductive material situated upon and covering the front side of said microchannel plate for trapping ions and low energy level electrons; whereby the contrast resolution capability and the operational life of the tube is enhanced.

Claim 15

An image intensifier comprising: front end means for receiving an optical image; a photocathode; means for directing said optical image upon said photocathode; a target electrode, said target electrode including a metal backing layer; a microchannel plate, said microchannel plate located between and spaced from said photocathode and target electrode with the distance between said plate and said photocathode being less than the distance between said plate and said target electrode, said microchannel plate having a front end facing said photocathode and a rear end facing said target electrode; first voltage supply means for establishing a low potential difference in the range of 400 to 1,000 volts between said photocathode and said microchannel plate to accelerate electrons toward said microchannel plate; second voltage supply means for establishing a high potential difference in the range of 3,000 to 8,000 volts between said microchannel plate and said target electrode to accelerate electrons toward said target electrode; third voltage supply means for proviDing a potential difference between the front and back ends of said microchannel plate to cause electrons to travel from the front end to the back end of said microchannel plate; and a very thin non-self-supporting layer of electrically conductive material situated upon and covering the front side of said microchannel plate for trapping ions and low energy level electrons; whereby the contrast resolution capability and the operational life of the tube is enhanced.

Claim 16

The invention as defined in claim 12 wherein said thin non-self-supporting layer of electrically conductive material is substantially optically transparent.

Claim 17

The invention as defined in claim 13 wherein said layer comprises the material aluminum and is of a thickness within the range of 50 to 400 A.

Claim 18

The invention as defined in claim 14 wherein said first voltage means comprises approximately 600 volts.

Claim 19

The invention as defined in claim 15 wherein said second voltage means comprises approximately 5,000 volts.

Claim 20

In a light amplification device of the type which includes in vacuum in an envelope; a photocathode for receiving an optical image on a front surface and emitting a corresponding electron image from its back surface; a phosphor screen electrode for converting electron images incident thereupon into a corresponding visual image, said phosphor screen including a metal layer covering its rear side; electron multiplying microchannel plate means located intermediate said photocathode and said phosphor screen electrode, having a front end facing said photocathode and a rear end facing said phosphor screen electrode for receiving an electron image at an input end and emitting a corresponding electron image of greater intensity at its rear end, said microchannel plate being spaced from said photocathode by a first predetermined distance in the range of 0.005-inches to 0.020-inches and being spaced from said phosphor screen electrode by a second predetermined distance, greater than said first predetermined distance, in the range of 0.030-inches to 0.050-inches; a thin non-self-supporting substantially optically transparent layer of material situated upon and covering said front face of said microchannel plate for trapping ions and low energy level electrons and passing incident light, said layer having a thickness in the range of 50 to 400 A; first means for providing a first voltage between said photocathode and said microchannel plate; second means for providing a second voltage between the front and rear surfaces of said microchannel plate; third means for providing a third voltage between the rear surface of said microchannel plate and said phosphor screen electrode, said third voltage being at least twice as large as said first voltage.

Claim 21

In a light amplification device of the type which includes in vacuum in an envelope; a photocathode for receiving an optical image on a front surface and emitting a corresponding electron image from its back surface; a phosphor screen electrode for converting electron images incident thereupon into a corresponding visual image, said phosphor screen including a metal layer covering its rear side; electron multiplying microchannel plate means located intermediate said photocathode and said phosphor screen electrode, having a front end facing said photocathode and a rear end facing said phosphor screen electrode for receiving an electron image at an input end and emitting a corresponding electron image of greater intensity at its rear end, said microchannel plate being spaced from said photocathode by a first predetermined distance in the range of 0.005-inches to 0.020-inches and being spaced from said phosphor screen electrode by a second predetermined distance, greater than said first predetermined distance, in the range of 0.030-inches to 0.050-inches; a thin non-self-supporting substantially optically transparent layer of material situated upon and covering said front face of said microchannel plate for trapping ions and low energy level electrons and passing incident light, said layer having a thickness in the range of 50 to 400 A; first means for providing a first voltage between said photocathode and said microchannel plate; second means for providing a second voltage between the front and rear surfaces of said microchannel plate; third means for providing a third voltage between the rear surface of said microchannel plate and said phosphor screen electrode, said third voltage being at least twice as large as said first voltage.

Claim 22

The invention as defined in claim 17 wherein said material comprises a metal.

Claim 23

The invention as defined in claim 18 wherein said metal comprises aluminum.

Claim 24

The invention as defined in claim 19 wherein said thickness of said layer is approximately 75 A.

Claim 25

The invention as defined in claim 20 wherein said first voltage comprises approximately 600 volts and wherein said third voltage comprises approximately 5,000 volts.

Claim 26

The invention as defined in claim 21 wherein said first distance comprises approximately 0.012-inches and wherein said second distance comprises approximately 0.038-inches.

Claim 27

The invention as defined in claim 17 wherein said first voltage is in the range of 400 to 1,000 volts and said second voltage is in the range of 3,000 to 8,000 volts.

Claim 28

The invention as defined in claim 23 wherein said material consists of a member selected from the group consisting of aluminum, boron, beryllium, boron carbide, silicon oxide, silicon dioxide, magnesium oxide, magnesium fluoride, and aluminum oxide.

Claim 29

The invention as defined in claim 17 wherein said mAterial possesses a specific gravity in the range of 1.0 to 4.0.

Claim 30

The invention as defined in claim 17 wherein said material possesses a secondary emission characteristic of at least 3 measured at 400 volts.

Claim 31

The invention as defined in claim 17 wherein said first voltage and said first distance define an electric field, E, in the range of 1 X 104 to 4 X 104 volts per centimeter and wherein said third voltage and said second distance define an electric field in the range of 3 X 104 to 6 X 104 volts per centimeter.