OWNERS MANUAL | Cobolt Skyra™ |
D0423-E JANUARY 2018
33 | 45
Settings Optimization in modulation mode
Cobolt Monitor™ software allows the user to optimize the laser performance while in modulation mode. During
manufacturing the DPL settings are in digital modulation at 1 kHz and a 50% duty cycle. When modulating with a
different input signal the user can expect changes in the pulse shape, peak power and average power. TEC 3, High
current and Low current can be adjusted to re-optimize performance, though 100 % of the performance may not be
recoverable.
An example of the effect of modulation frequency on pulse shape at 1 kHz versus 10 kHz
High Current Adjustment
It is not always sufficient to increase the TEC 3 temperature to achieve maximum average power. When necessary the
High current level can be increased up to as much as 3000 mA, the maximum safe operating current for DPL as set at
the factory.
Low Current Adjustment
If the application requires, it is possible to set the low current to
0
mA where a perfect dark state is required, but
adjusting the lower current can have adverse effects on pulse shape.
TEC 3 Adjustment
The DPL’s optical output power is influenced heavily by the match between the pump diode’s emission spectrum and
the laser crystal’s gain spectrum. Modulation mode operation is achieved by direct modulation of the drive current to
the pump diode. Decreasing the ON time and thereby the diode temperature, must be compensated by an increase in
the platform temperature to maintain a constant pump diode wavelength. TEC 3 is used to control the platform
temperature when in modulation mode and can be used to optimize the temperature of the pump diode. Adjust the
TEC3 temperature inversely with duty cycle.
