Camera, Color, HDTV
Wednesday, August 30, 2006
A Color HDTV Camera has been designed and developed where light passes through a color separation prism and is focused onto image intensifier tubes. Each image intensifier tube consists of a photocathode for converting light into electrons, a multi channel plate (MCP) for electron multiplication, and a phosphor fiber faceplate for converting electrons back to light.
The MCP has millions of micro holes with a hole pitch of 13 µm. The MPC generates secondary electrons on the walls of the holes. A two-stage MCP configuration is used to compensate for image intensifier optical losses. An amplification factor of one million times can be achieved. The MCP brightened image is reduced in size by a relay lens and projected onto a CCD camera without a fiber faceplate (with no fiber faceplate, a less degraded image is obtained). Image sensitivity in the longer wavelength is 2000 lux at f/n 8. Registration errors were reduced to 0.5 TVL with a horizontal resolution of 899 TVL, without any observable image lag.
A key feature of this Camera is its ability to observe dark objects with high background noise. The Camera is driven with high frequencies in order to carry large amounts of data resulting in S/N ratios of 9 dB or lower. A lower S/N ratio under dark illumination produces lower resolution and a degraded image. The Camera uses a large imaging image intensifier tube to achieve a high S/N ratio by projecting a reduced image onto a CCD camera. The Camera objective lens' size is increased in proportion to the area of the imaging surface of the CCD’s active face area.
Source: "Video astronomy with an HDTV”, by Mike Obstgarten, Advanced Imaging, March 2000 Reference: Keizo Majima, Shunji Sunazaki, Junichi Yamazaki, and Takashi Ando, Japanese Broadcasting Corp., NHK, Tokyo, Japan
Industrial Products
posted by JD52 @ 9:41 PM,
