MIRcat OPERATION
•
D11-00028-02-A
Page
20
of
54
for CW mode or Pulsed >10% Duty Cycle only.
Ethernet
RJ-45 connector. Not yet supported.
DB-9
Used to connect the
MIRcat
to an external Data Acquisition System. See
next section for pin out and signal description.
Continued from last page.
USB connector
Used to connect the
MIRcat
to an external computer. Uses HID
interface. See USB communication later in manual.
Key Switch
Used to Enable Laser Arming. Key cannot be removed in Armed
(horizontal) position.
Trigger In/Out
BNC connectors: A TTL input/output pulse into 50Ω load is provided for
synchronizing external instruments and data acquisition equipment
with the rising edge of the laser trigger pulse. See timing diagrams in
section 3 on Triggering and Acquisition Signals.
Modulation Input
(CW only)
Allows an external signal to be applied to the QC current bias for
external modulation. CW only, not yet supported.
Laser Armed Status LED
Laser is Armed when illuminated. Key switch must be horizontal, and
Arm laser selected in Control Panel GUI.
2. Triggering and Acquisition Signals on DB-9 Connector
The DB9 connector on the back of the MIRcat has the following TTL signals for timing and control with a
Data Acquisition System (DAQ):
Pin
Signal description
1
Scan direction:
Active HI output. It is always HI when going from a lower to higher wavelength/wave number, and LO
when going in the opposite direction. For example, if scan units are cm
-1
, going from 1200 to 1400 cm
-1
will
cause the signal to go HI, and LO in the other direction. If scan units are in um, going from 7 to 10 µm will
cause the signal to go HI, and LO in the other direction. This signal is dependent on scan units.
2 Tuned: HI when the laser has scanned to a step wavelength
Active HI output. This signal goes HI when the laser is tuned to a correct wavelength and is
emitting light. When scanning it will go HI while the laser is emitting light and LO when laser is off.
3 Wavelength trigger: HI when laser has scanned to wavelength
Active HI output. This signal is only used when Wavelength Trigger is selected in the
Settings. When in this mode, the laser will emit a single laser pulse using the pulse width specified in the
settings at the specified interval. For example, if scanning from 7 to 10 µm, and the WL trigger start and
stop are set to 7.5 µm and 9.5 µm, respectively, and the WL trigger interval is every 0.1 µm, this signal will
go HI when the scan crosses 7.5 µm, 7.6 µm, 7.7 µm, etc. The duration of the HI pulse on the WL trigger
