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Chapter 4
4.5.3.6
Im Lim
The photodiode current limit is a software monitored limit on the current delivered
from the photodiode. Because this limit is a software monitored limit, shutdown can
occur up to a second after the condition is true. The oscillator channel of the MOPA
module does not support this setting.
4.5.3.7
Po Lim
Like the Im Lim, the photodiode power limit is a software monitored limit on the
power delivered from the photodiode. For this limit to function, the user must set a
PD Resp value other than zero. Because this limit is a software monitored limit,
shutdown can occur up to a second after the condition is true. The oscillator channel
of the MOPA module does not support this setting.
4.5.3.8
Tol Time and Tol Iop
The Tol Time and Tol Iop elements are used for determining when the laser is "in
tolerance." The Tol Time value is expressed in seconds, and can range from 0.001
seconds to 50 seconds. The Tol Iop value is displayed in mA, and can range from 0.1
mA to 100 mA. When operating in Im or Po modes, The Tol Iop setting is ignored,
and fixed values of 50 µA and 50 mW, respectively, are used. The laser is considered
in tolerance after it has been within the tolerance setting for the set number of
seconds. If at any time it goes outside the tolerance range, the time restarts at zero.
As an example, if the Tol Time is set to 5 seconds, the Tol Iop is set to 2 mA, and
the current set point was 1000 mA, the laser module would have to stay within 998
mA and 1002 mA to be within tolerance. Out of tolerance is indicated by a OutT
status field on the bottom of the Laser Main Screen.
4.5.3.9
Intermittent Contact (Int Contact)
The Int Contact setting controls the detection of intermittent contacts caused by
faults cables or connectors. An intermittent contact, if enabled, will shutdown the
laser with an open circuit error. The system allows the user to disable the circuit
when working in an electrically noisy environment that might cause a false detection.
The circuit is automatically disabled when in high bandwidth mode. The MOPA
module does not have an intermittent contact circuit, so it does not support this
setting.
4.5.3.10
PD Resp
The PD Resp element is the conversion factor between photodiode current and
photodiode power, and is expressed in µA per mW. If this value is zero, the system
will not operate in Po mode. The oscillator channel of the MOPA module does not
support this setting.
Laser Diode Driver Module Operation
51
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