Patent ID: 7738632

Claim:
An x-ray tube comprising: a tube housing; a cathode at said tube housing, said cathode comprising an optically activatable material that, when optically activated, emits electrons into an interior of said tube housing; a laser that emits a laser beam onto said cathode to optically activate said cathode; said tube housing comprising an outer wall surrounding an evacuated region, and said cathode forming a portion of said outer wall having a cathode exterior at an exterior of said outer wall, and said laser being disposed outside of said tube housing and emitting said laser beam onto said cathode exterior; a transmission anode in said tube housing toward which said electrons emitted by said cathode are accelerated to strike said anode to cause x-ray radiation to be emitted by said anode, said x-ray radiation including useable x-rays; a cooling channel having coolant filling therein in thermal communication with said transmission anode to cool said transmission anode; an evacuated region in said tube housing between said cathode and said transmission anode; said tube housing having an exit window therein through which said useable x-rays exit from said tube housing; and said transmission anode being disposed in said tube housing between said evacuated region and said cooling channel, and said cooling channel being disposed in said tube housing between said transmission anode and said exit window with said useable x-rays passing through said coolant toward said exit window.