It was first produced in the year 1945 and because of its superior performance it’s soon replaced all earlier tv camera tube like image dissector, iconoscope and orthicon. 

It has the following qualities: 

• It has high photo graphic sensitivity. 
• It provides a very dependable service. 
• It provides an excellent response over a wide. 

RANGE of illumination level varying from bright sunlight to dark shadow. As a result of this, image orthicon remained in popular TV studio use for a long period but it is now being replaced by plumb icon.

Principle of working:

• A lens system focuses light from the scene on to a translucent photo cathode.
• Electrons gate emitted from the various points on photocathode SURFACE in proportion to the illumination .
• These photo electrons travel to a THIN glass target causing secondary emission from it.
• These secondary electrons get collected by a fine mesh placed close to the glass target plate as shown fig.
• This causes electron deficiency distribution or POSITIVE charge distribution on the photo cathode.
• This positive charge distribution originally on the front surface of the target plate leaks through thin plate to the back surface.
• A low velocity scanning beam from an electron at the other end of the image orthicon tube scans the back surface of the target plate following a predetermined scanning pattern.
• The electroned is slowed down to a non zero velocity as it approaches the target.

From a dark element ,the scanning electron beam is returned UNAFFECTED .However ,at light element(positively charge element),the scanning beam is deprived of some of its electrons to netralise the positive charge so that the returning electrons to neutralize the positive charge so that the returning electron beam contains lesser electron .This varying density returning beam is fed to an electron multiplier.

It was first produced in the year 1945 and because of its superior performance it’s soon replaced all earlier tv camera tube like image dissector, iconoscope and orthicon. 

It has the following qualities: 

Range of illumination level varying from bright sunlight to dark shadow. As a result of this, image orthicon remained in popular TV studio use for a long period but it is now being replaced by plumb icon.

Principle of working:

From a dark element ,the scanning electron beam is returned unaffected .However ,at light element(positively charge element),the scanning beam is deprived of some of its electrons to netralise the positive charge so that the returning electrons to neutralize the positive charge so that the returning electron beam contains lesser electron .This varying density returning beam is fed to an electron multiplier.