THORLABS PICO D, Руководство пользователя

Страница: 23 / 48

23
When digital control signal _OPTICAL_POWER_ENABLE is set to HIGH (5 V) the
laser diode, inside the PICO D unit, is turned off irrespective of analog optical power
input voltage.
The _OPTICAL_POWER_ENABLE signal is well suited for implementation of a
safety circuitry that switches off the laser in critical situations.
IMPORTANT
The _OPTICAL_POWER_ENABLE signal should NEVER be used for modula-
tion of the optical power!
2.5.3.2.5 Digital control: _CONSTANT_CURRENT_ENABLE
The digital control signal _CONSTANT_CURRENT_ENABLE i is used for enabling
current tuning. Read paragraph 2.5.4.2 carefully before you use this feature.
2.5.3.2.6 Digital control: _MODE_HOP_ADJUST_ENABLE
Control signal for enable temperature adjustment of the cavity temperature.
2.5.3.3 Digital status signals
The digital status signals are defined having 0V (LOW) as ON/TRUE/ERROR and
5 V (HIGH) as OFF/FALSE/Safe. The digital status signals can be read form the in-
terface. Carefully read paragraph 2.5.3.1 (Definition of the logical states) before con-
necting PICO E. The digital output circuitry is shown in Figure 2–11.
Table 2-5 The digital status signals
Name Short description
_SYSTEM_ERROR
This status signal indicates a major fault,
could be tuning motor over-temperature, control loop
overload
_WAVELENGTH_ERROR
This status signal indicates that the PICO D doesn’t follow
the applied wavelength sweep voltage.
_OPTICAL_POWER_ERROR
This status signal indicates when the laser current exceeds
100 mA
_TEMPERATURE_ERROR
This status signal indicates that the laser cavity is operating
at correct temperature
_MODE_HOP_DETECT
This status signal indicates that a mode hop has been
detected.
Figure 2–11 Digital output circuitry