LDM9T
Chapter 4: Setup
Page 6
15827-D02
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Make sure the laser diode is flush with the cold plate. Install the
appropriate mounting flange, either Ø5.6 mm or Ø9 mm, over the laser
diode and secure in place using the provided screws. A spare set of
screws is provided with the mount.
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Lastly, reattach the cover plate using the two 2-56 socket head screws.
WARNING
Make sure the laser diode is installed correctly and the polarity switches on the
mount are set as per the laser diode pin configuration provided by the
manufacturer. Connecting the LD driver to mount with incorrect installation may
damage the laser diode.
4.2. Special Note for 4-Pin Laser Diodes
The LDM9T also supports 4-pin laser diodes. Insert the laser into the 4-pin
socket and note which laser pin is in the 6 o’clock position (laser anode or
cathode). Also, note which photodiode pin is in the 12 o’clock position (anode or
cathode). The mount will tie the laser and photodiode pins located at 9 o’clock
a
nd 3 o’clock together and also to ground. By noting which polarity pins are
inserted in the socket, you can convert the 4-pin layout to one of the 3-pin layouts
in Figure 2 on page 5. Set the LD and PD polarity switches accordingly.
4.3. Laser Diodes without a Monitor Photodiode
Laser diodes without a monitor photodiode will also work with the LDM9T. The
laser diode pins must be positioned between the LD and G positions. Some 2 pin
packages will not align with the laser diode socket, but 3 pin versions can be
mounted.
Pin style G is a special case. To properly operate this laser diode style, the
internal jumper JP2 needs to be installed. This will short the PD pin to G. The
user will need to determine if they want to operate with the LD anode or cathode
grounded. The laser diode needs to be oriented so that the preferred grounded
LD pin is oriented to the PD pin. This will align the remaining laser diode pin into
the LD socket. The laser diode pin oriented toward the PD pin will determine the
switch position.
Laser Lead in PD Socket
LD Switch
PD Switch
Anode
AG
CG
Cathode
CG
AG
It should be noted that both PD pins will now be grounded giving erroneous
readings on controllers with photodiode measurement circuits.
