O P E R A T I O N S
Operating from the Front Panel
7/01
LDC-3700 Series
17
C H A P T E R
2
Set the Range
Next, in the
RANGE
section set the laser controller’s current source range by selecting the 200 mA
range indicated by the accompanying LED. You will need to press the
SELECT
push button twice to
change the range. It must be pressed twice quickly (within less than 1 second) to switch between
modes, and the LASER output must be off (LASER MODE ON indicator unlit) in order to change
ranges.
Select the Laser Display
Configure the display so that it reads in mA by selecting
I
in the
LASER
DISPLAY
section of the
front panel (directly underneath the
LASER
display. The enunciators next to the display will indicate
the display mode (mA illuminates when "I" is pressed). The
LASER DISPLAY
switch
section
is also
used to select the
I
PD
(photodiode current,
µ
A),
P
PD
(laser power, mW), or
V
(forward voltage, V)
measurement or set point values. The
SET
switch can be used to view the set point of any of the
LASER
DISPLAY
parameters. When the (
LASER
DISPLAY
)
SET
switch is pressed, a display set
point value is indicated by the corresponding display mode enunciator flashing.
At this point the Controller is in Constant Current Mode, (I), in the 200 mA range, and the display is
reading in mA. Next, we need to adjust the set point of the laser current source. The controller can
be changed to set point mode a couple of ways.
Adjusting the Set Point
To adjust the set point of the Controller current source to 150 mA, set the instrument to
LAS
mode
by pressing the appropriate push button in the
ADJUST
section of the front panel. The
LAS
indicator
will be illuminated. Turn the adjust knob clockwise to increase the set point (as indicated on the
LASER
display), or counterclockwise to decrease the set point. When the
ADJUST
knob is turned,
the controller automatically changes to set point mode indicated by the display mode enunciator
flashing. Before adjusting the set point check the
LASER
display for proper display mode; the
display mode determines which set point is being adjusted. Adjust the set point to 150 mA. Pressing
the
SET
switch in the
LASER
DISPLAY
section will also change the controller to set point mode.
Make sure that the
mA
enunciator next to the display is illuminated before adjusting the set point.
After an adjustment has been made, and the (
LASER
DISPLAY
)
SET
switch and
ADJUST
knob are
released, the
SET
mode will time out in three seconds. The new set point will be stored in non−
volatile memory. If the original display mode differed from the newly adjusted set point, the
LASER
display will revert to the original display mode (
I
,
I
PD
, or
P
PD
).
Note:
When adjusting any LASER parameter, display mode or operating mode, the
LAS
indicator in the
ADJUST
section must be lit.
We are not quite ready to turn on the laser. One of the laser protection features our controllers offer
is a fully independent hardware current limit. The current limit protects your laser by never allowing
PRESS TW ICE
2 0 0 mA
5 0 0 mA
RANGE
LA SER DISPLA Y
I
I
PD
P
PD
V
SET
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