Kodak DirectView CR 825 Theory Manual page 66

THEORY GUIDE
10DEC05
Operation of the PMT/DAS BOARD:
TG4825-1
Page
66 of 120
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H194_5046HC
1. The 2 PMTs connect to the PMT/DAS BOARD A5. The HIGH VOLTAGE POWER SUPPLY
feeds power to the HIGH VOLTAGE DIVIDERS. Each PMT has a HIGH VOLTAGE
DIVIDER that sends the given levels of high voltage to the components inside the PMTs.
2. The ANODE of each PMT is connected to a CURRENT-TO-VOLTAGE AMPLIFIER, which
changes the small current signal from each PMT into a corresponding voltage signal.
Each of the voltage signals moves through a PMT GAIN CONTROL D/A CONVERTER.
These CONVERTERS change the signal level from each PMT to adjust for gain variations
from PMT to PMT.
A5
analog
ANODE
voltage
signals
PMT1
ANODE
PMT1
to HIGH
VOLTAGE
DIVIDERS
HIGH VOLTAGE
POWER SUPPLY
PMT/DAS BOARD
2 CURRENT-TO-VOLTAGE
AMPLIFIERS
2 PMT GAIN CONTROL
D/A CONVERTERS
SUMMING AMPLIFIER
LOW PASS FILTER
16-BIT A/D CONVERTER
16 bit
8 bit
DATA MULTIPLEXER
8 bit
A3
DIGITIZER BOARD
PIXEL CLOCK
FIFO BUFFER
A2
MCPU BOARD
BUFFER
raw image
data
INTERNAL PC
Optical
digital
image
data
processed
digital
images
to network