Service manual

LUMISCAN ACR-2000 SERVICE MANUAL - SECTION 4.0 THEORY OF OPERATION
4-2
4.2 System Configuration
The configuration of the LUMISCAN ACR-2000 READER includes optics, electrical and power supply
assemblies, PCAs for scanner control and data acquisition, and a plate transport assembly.
4.3 Optical Beam Path
The READER contains a laser, laser power supply, fixed optics and mirrors, a scanning galvanometer, light
detection system and a electronics subsystem for control.
The READER uses a red, high-power solid-state laser diode (about 35 mw at 658 nm) as the beam source.
The laser diode energy is coupled into a single-mode fiber which is then focused through a lens to produce a
very high-quality spot. The beam is deflected by a galvanometer scanner to produce the sweep. The folding
mirror bends the beam so as to sweep the beam horizontally across the image plate as the image plate
travels vertically. See Figure 4-2.
The beam passes through the integrating collection cylinder and strikes the phosphor surface of the image
plate. The red light striking the image plate stimulates blue emission from the image plate in proportion to
the X-ray energy stored in the image plate as a result of the exposure. This blue light is collected by the
integrating cylinder. The red light is blocked from reaching the photomultiplier tubes by blue glass filters.
The collected blue light is detected by photomultiplier tubes, which convert the photons into a signal. This
signal is then logarithmically amplified, corrected for spatial variations in the system sensitivity across the
width of the screen, and then digitized by an A/D converter.
Figure 4-2 LUMISCAN ACR-2000 READER Optical Beam Path