Kodak DirectView CR 825 Theory Manual page 64

THEORY GUIDE
10DEC05
Collection of the Blue Light
TG4825-1
Page
64 of 120
ANODE
0 V DC
H194_5043HC
When the red light from the LASER reaches the SCREEN, blue light is emitted in random
directions. The COLLECTOR captures most of the rays of blue light and provides the
deflection of the rays toward the FACE of the PMTs.
Changing the Blue Light to Electrical Current
1 Some of the red light from the LASER that reaches the SCREEN is reflected and enters
the COLLECTOR. A BLUE FILTER between the COLLECTOR and the PMTs rejects
most of the red light and allows the blue light to enter. The PMTs receive only the blue
light from the SCREEN.
2 Inside the PMT are a number of components that are connected to varying levels of high
voltage. The circuits on the PMT/DAS BOARD separate the high voltage into a
DYNODE 7 DYNODE 6 DYNODE 3
-100 V DC -150 V DC -300 V DC
DYNODE 8 DYNODE 5 DYNODE 4
-50 V DC -200 V DC -250 V DC
FOCUSING ELECTRODE
DYNODE 2
-350 V DC
Path of electrons from
PHOTOCATHODE
DYNODE 1
-400 V DC
-500 V DC
Blue Light
From PLATE
/SCREEN
Blue Light
From PLATE
/SCREEN
PHOTOCATHODE
-600 V DC
Optical