Stanford Research Systems LDC500, Руководство по эксплуатации и обслуживанию

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5.1 Laser Diode Driver Messages 5 – 3
5.1.5 Responsivity
T3"
?;-
The photodiode responsivity cannot be modified or calibrated when
the laser is ON and operating in CP milliwatt control mode. See
sections 3.2.3.6 and 3.2.3.7.
5.1.6 Photodiode current overflow
1/
?43#/&)W*
Any time a new photodiode responsivity is set (either by
CALP
or
RESP ), the LDC500 will check that the implied value of PD Ilim,
based on the present value of PD Plim, does not exceed the maxi-
mum photodiode current of 5000
μ
A (10,000
μ
A. for LDC502). If this
warning occurs, either the responsivity is too high, or the photodiode
power limit (
PWLM
) needs to be reduced.
"#
?43#/')W*
Similarly, any time a new photodiode power limit ( PWLM ) is set,
the instrument checks that the physical photodiode current limit still
remains less than 5000
μ
A (10,000
μ
A. for LDC502). Again, if this
occurs, either the responsitivity is too high, or the photodiode power
limit is too high.
3#%
E#)W*
Finally, when mW units are selected, the derived photodiode cur-
rent limit (using responsivity) may exceed 5000
μ
A (10,000
μ
A. for
LDC502). Again, reduce the power limit or the responsivity value to
resolve the problem.
5.1.7 Responsivity underflow
3#%3#/
7?(8X3"
When calibrating responsivity (see section 3.2.3.6), a large value for
measured power might result in the responsivity value less than
the minimum, 0.051
μ
A
/
mW. If this occurs, either the power mea-
surement is mistaken, or the photodiode circuit is open (too low a
photodiode current).
LDC500 Series Laser Diode Controllers