Modified version of the Minsk
STABILIZED TWO-WAVELENGTHS
LED-BASED PULSED AND CONSTANT LIGHT
SOURCE
CERN
2004
TTL levels:
FREEZE:
Stabilization ON/OF
Constant/pulsed light
mode
TTL pulses: Color selection
Light pulse trigger: NIM pulses
Original control via the TTL levels and front panel switches is replaced by the full
remote control by TTL levels and pulses only.




Any regime changes can be made only is FREEZE level is “1”. FREEZE = 0 means the
pulser is running according to the previously defined settings.
To setup operation in pulsed mode, blue LED:
1. put FREEZE level to “1”
2. sent TTL pulse to the “blue” input of the Color selection cable
3. start to send TTL pulses to the left (“blue”) Light pulse trigger LEMO
connector ( could be sent all the time, pulser become sensitive to it only is blue
pulsed more is selected )
4. choose the output signal level by “INTENSITY + - “ switch
5. press “Set” button: red LED above the button will light, it indicates that the
internal output intensity procedure is started. Wait for this light get OFF
6. put “FREEZE” level to “0”
7. “high” “low” yellow lights at the right side of the box should start to blink –
means putput regulation is running. If one of the lights is ON all the time –
outut signal is too low or too high. Repeat the adjustment procedure.
“Blue” and “Red” stabilization are logically independent. I means once defined, the
stabilization level is stored in the memory and will be restored as soon as the
corresponding color pulsed mode is selected. Of course all settings are lost on box
power OFF.
Constant light mode is selected by CONSTANT level “1” ( green indicator should
light). By setting it bact to “0” you restore the previous pulsed mode, including color
and output amplitude.
Stabilized Light Pulse Source
 !!! VERY IMPORTANT. The box operates normally only if one of the
output fibers is connected to the feedback input.
Stabilized Light Pulse Source
Appendix 1. Original text of the light
source description
STABILIZED TWO-WAVELENGTHS
LED-BASED PULSED AND
CONSTANT LIGHT SOURCE
MINSK
2003
Stabilized Light Pulse Source
Stabilized Two-wavelengths LED-based Light Pulsed Source
Stabilized two-wavelengths LED-based pulsed light source (Light Pulser) is designed for
monitoring of electromagnetic calorimeter detector cells at two wavelengths, namely
1=460 nm (BLUE channel) and 2=638 nm (RED channel). Light at the output is
uniformized in the quartz cylinder of 8.0 mm diameter.
General Technical Data
1 Number of photons at the
. light output
2
.
3
.
4
.
Light pulse duration
adjustment range (typical)
Non-stability of photon
number per pulse (after 30
min warming-up)
Repetition rate of light
pulses (with external
synchronization)
Input signals “FREEZE”,
“COLOR”, “CONSTANT”
Input signal “START”
5
.
6
.
7 Output signal “MONITOR”:
.
amplitude
shaping
8 Power requirements, min:
.
+6 V10%
+24 V10%
-6 V10%
-24 V10%
9 Power consumption
.
BLUE channel:
 500×106 photons for 20 ns optical pulse duration
 5000×106 photons for 100 ns optical pulse
duration
RED channel:
 500×106 photons for 20 ns optical pulse duration
 5000×106 photons for 120 ns optical pulse
duration
20 – 100 ns FWHM
 0.1%
1 Hz  1 kHz
TTL standard
NIM standard
0 V  4.5 V (3 V in stabilization mode)
quasi-Gauss
 250 mA
 500 mA
 1000 mA
 300 mA
~ 25 W
Stabilized Light Pulse Source
Technical description
Light Pulser diagram is shown in Figure.
Light Pulser contains two output channels (RED and BLUE) and one PIN diode reference
unit. The description below is valid for both channels
Input pulse “START” activates monostable multivibrator made of the ECL logic elements
and built-in digitally controlled delay line providing electronic adjustment of pulse
duration. This signal of predefined duration drives the current switch that connects
digitally controlled current source to the input of fast linear current amplifier with superbright LED as a load. Short time of light flash is achieved by using the active quenching
circuit. Light from LED goes through the optical system with light splitter to the input of
optical feedback circuits. Thermo-stabilized PIN photodiode is used as the photo detector
there. Signal from the photodiode, amplified by the charge-sensitive preamplifier and the
precise adjustable shaping amplifier, goes to analog comparator, which compares the
amplitude of the PIN photodiode signal with the reference voltage U REF. Comparator
generates the signal proportional to the PIN diode to UREF difference, which is processed
by 12-bit digital-to-analog integrator and goes to LED current control circuit.
Controls located on the Light Pulser front panel:












push-button “SET” with LED indicator for gain adjustment of the shaping amplifier;
stabilization circuit on/off: LEMO connector “FREEZE” with LED indicator;
constant blue light on/off: LEMO connector “CONST.” with LED indicator;
“START BLUE”: LEMO input;
“START RED”: LEMO input;
“Color”: LEMO input;
“Intensity” indicator;
“ Intensity” switch;
“UDAC” DAC output;
“MONITOR” shaping amplifier output;
stabilization mode LED indicators : “HOLD”, “LOW”, “HIGH”;
“POWER”: power supply connector.
Optical connectors located on the rear panel:
 “LIGHT OUTPUT”: flange type connector (diameter of the output light beam is
defined by output quartz cylinder and is equal to 8.0 mm)
 PIN-diode connector of DNP-type for 1mm plastic optical fiber.
Stabilized Light Pulse Source
Operation manual
1. Installation
 Connect power cable to the “POWER” connector on the rear panel. Power pins
specification is given in Appendix 1.
 Connect fiber bunch to the “LIGHT OUTPUT” optical connector on the rear panel.
Design of the connector flange is shown in Appendix 2.

NOTE: for the optimal light transmission the fiber bunch should be in direct
optical contact with the output quartz cylinder
 Connect one fiber of fiber bunch to the PIN-diode optical connector located on the rear
panel.
 Device requires warm-up time at least 30 minutes.
 Connect NIM Pulse Generator output to the “START BLUE” or “START RED” input.
 Connect TTL level high to connector “FREEZE”. The “FREEZE” LED indicator will
light on.
 Send TTL pulse to the desired “COLOR” input. The corresponding LED indicator
should light on.
NOTE: Change of color possible only in “FREEZE” ON state.
Only ONE color output can be active at a time.
 Adjust intensity of the light flash by “Intensity” push buttons, checking amplitude of the
signal on a detector output via oscilloscope or pulse-height analyzer.
 Press push-button switch of shaping amplifier gain adjustment “SET”. Corresponding
LED indicator will light on during automatic gain adjustment. Repetition rate of the
“START” pulses of 200-300 Hz is recommended for installation.
NOTE: time of gain adjustment will depend on frequency of start pulses; at 1
kHz start rate this gain adjustment will take several seconds.
 After “SET” LED switch off, start stabilization system by removing TTL level from the
“FREEZE” inlut.
2. Operation
“HOLD” LED on the front panel should light, “LOW” and “HIGH” LEDs should blink in
the stabilization mode.
If only “LOW” or “HIGH” LED lights, it means that the device is out of the adjustment
range. It may happen due to wrong order of installation. In this case repeat the device
installation sequence.
Stabilized Light Pulse Source
"HOLD"
THERMOSTAT
THERMO
STABILIZER
"MONITOR"
“SET”
"LOW”
COMPARATOR
PIN
LED
To DC source
=
PIN
PREAMP
"HIGH”
LED
CURRENT
CONTROL
"UDAC "
SHAPER
"UREF "
LED
“FREEZE”
UREF
"INTENSITY”
To the second channel
LED
QUENCHING
STAGE
"START”
PULSE
GENERATOR
POWER
STAGE
Light Pulser diagram
Stabilized Light Pulse Source
Appendix 1
Power supply connector wiring diagram
1
2
3
4
5
6
7
8
9
10
11
12
+24 V
- 24 V
Reserved
+6 V
Ground
Reserved
Reserved
Reserved
-6V
Reserved
Reserved
Ground
Connector type: “BURNDY”
Appendix 2
Design of flange for optical output connector
(dimensions in millimeters)
Stabilized Light Pulse Source