4
The DC component is separated between the preamplifier and the CD amplifier, and is
compared with the reference voltage in order to control the voltage of the PM power
supply. This voltage is also applied to the PM detector, changing the PM sensitivity.
The AC component is converted to a digital signal after being amplified by the
preamplifier and the CD amplifier.
The main unit and the personal computer communicate through the RS-232C interface.
All parameters of the main unit are designated from the personal computer. The CD
signal and PM voltage are communicated to the personal computer through the RS-
232C interface after being converted to digital signal and stored in the buffer memory.
CPU
RS-232C I/F
A/D D/A
RS-232C I/F
PC
SVGA
Parallel I/F
PM
Sensor
Light Source
Monochromator
Sample
Chamber
Light Source
Power Supply
Slit Motor
Driver
Modulator
Driver
Preamplifier
Wavelength
Motor Driver
Shutter
Driver
CD Amplifier
PM Power
Supply
I/O
External
Input 1
External
Input 2
Buffer Memory
Program Memory
Main Unit
PC
Keyboard
CRT Display
Printer
Fig. 1.3 Block diagram of electrical system
1.2 Specifications
Light source :
150W air-cooled xenon lamp, or 450W water-cooled xenon
lamp
Detector :
Head-on photomultiplier tube
Modulator :
Piezoelastic modulator
Measurement wavelength range : 163 to 900 nm (standard detector)
163 to 1100 nm (optional detector)
Wavelength accuracy :
±
0.2 nm at 163 to 180 nm
±
0.1 nm at 180 to 250 nm
±
0.3 nm at 250 to 500 nm
