Cascaded image intensifier

A cascaded image intensifier, comprising:

• at least two sections in cascade, each of a first section and a last section out of said at least two sections including a photocathode unit adapted to convert photons to electrons and a screen unit adapted to convert electrons to photons;
• wherein a screen unit in said first section includes a bulk scintillator;
• and
• wherein said last section outputs a number of photons that equals or exceeds a number of photons which would have been outputted by said first section, had said first section instead included a phosphor screen unit.

A cascaded image intensifier, comprising:

• at least two sections in cascade, each of a first section and a last section out of said at least two section including a photocathode unit adapted to convert photons to electrons and a screen unit adapted to convert electrons to photons;
• and
• at least one voltage supply unit adapted to provide a potential difference between a photocathode unit and a screen unit in said first section that substantially ranges between 6 to 10 KV, and adapted to provide a potential difference between a photocathode unit and a screen unit in a section subsequent to said first section that substantially ranges between 20 to 30 KV;
• wherein said last section outputs a number of photons that equals or exceeds a number of photons which would have been outputted by said first section, had said at least one voltage supply unit been adapted to instead provide a potential difference between said photocathode unit and said screen unit in said first section that substantially ranges between 20 to 30 KV.

A cascaded image intensifier, comprising:

• at least two sections in cascade, each of a first section and a last section out of said at least two sections including a photocathode unit adapted to convert photons to electrons and a screen unit adapted to convert electrons to photons, said photocathode unit in said first section made of material differing from Gallium-Arsenide;
• and
• an ion barrier film in said first section;
• wherein said last section outputs a number of photons that equals or exceeds a number of photons which would have exited from said first section, had said first section excluded said ion barrier film.

A method of increasing a lifetime of a cascaded image intensifier, comprising:

• providing an image intensifier comprising at least two sections in cascade, wherein each of a first and last section out of said at least two sections includes a photocathode unit adapted to convert photons to electrons and a screen unit adapted to convert electrons to photons, and wherein said first section comprises a reducing element adapted to reduce ion-caused degradation of a photocathode unit;
• receiving light directed toward said image intensifier;
• limiting a number of photons emitted by said first section compared to a number of photons which would have been emitted had said first section excluded said reducing element;
• emitting a number of photons from said last section which equals or exceeds a number of photons which would have been emitted by said first section, had said first section excluded said reducing element;
• and
• utilizing said first section for a longer period of time compared to a period of time in which said first section would have been used, had said first section excluded said reducing element.

A method of intensifying light images, comprising:

• providing a system to intensify light images, said system including a cascaded image intensifier comprising at least two sections in cascade, wherein each of a first and last section out of said at least two sections includes a photocathode unit adapted to convert photons to electrons and a screen unit adapted to convert electrons to photons, and wherein said first section includes a reducing element adapted to (i) reduce ion-caused degradation of a photocathode unit of said first section and (ii) reduce a number of photons exiting from said first section from a first value to a second value;
• using said system to intensify light images;
• recognizing degradation of at least one photocathode in said image intensifier, which causes a lower number of photons exiting from a last section of said image intensifier than before;
• and
• adjusting said system in order to increase a number of photons exiting from said last section of said image intensifier and thereby compensating for said degradation of said at least one photocathode.

An optical system for use in automatic inspection of articles progressing along a production line, the system comprising at least one light detection unit, the light detection unit comprising a light detector for detecting a light response of the article to incident electromagnetic radiation, and a cascaded image intensifier accommodated in an optical path of light propagating from the article to the light detector, the cascaded image intensifier configured to have an increased lifetime, thereby allowing increased throughput of the production line, said cascaded image intensifier comprising:

• at least two sections in cascade, wherein each of a first section and a last section out of said at least two sections includes a photocathode unit adapted to convert photons to electrons and a screen unit adapted to convert electrons to photons;
• wherein said first section includes a reducing element adapted to:
• (i) reduce ion-caused degradation of a photocathode unit of said first section, and (ii) reduce a number of photons exiting from said first section from a first value to a second value;
• and wherein said last section outputs a number of photons that equals or exceeds said first value.