Christopher M Nelson

US Patent:

60914440, Jul 18, 2000

Filed:

Nov 25, 1997

Appl. No.:

8/977838

Inventors:

Thomas J. McCarville - Tracy CA
Christopher M. Nelson - Livermore CA
Henry Atiles - Loomis CA

Assignee:

United States Enrichment Corporation - Bethesda MD

International Classification:

H04N 718

US Classification:

348 82

Abstract:

A method and apparatus for continuously monitoring a melt surface is provided. The camera includes a CCD detector array, electronic shutter, and associated optical train mounted within a water cooled enclosure, all mounted within close proximity to the melt. Radiation shields surround the enclosure in order to attenuate the heat radiated from the melt to manageable levels. To minimize damage to the electro-optical components of the camera due to melt vapors and other contaminants, the camera enclosure includes a small viewing pinhole through which an inert gas is directed. The pinhole is small enough to minimize the gas flow rate while avoiding noticeable image diffraction. The small pinhole also provides a large depth of field, rendering high quality images of the melt. A compound lens system focuses the image into the CCD array to produce a near diffraction limited image over the angles of interest. The lens system contains a ninety degree turning element to protect the CCD array from direct exposure to x-rays produced at the melt surface.