4.5 Commands
4 – 27
Calibrate Photodiode Responsivity
CALP
f
Set the photodiode responsivity to correspond to a (real-time) optical
power measurement of
f
, in mW. There is no query form of
CALP
.
The
CALP
command requires an external laser power meter, and will
cause the LDC500 to recalculate the responsivity parameter (
RESP
)
to correspond to the externally-measured optical power,
f
.
See section 2.3.7 for further discussion of photodiode calibration.
Front panel:
LD :7
+-
.
CALP 12.04
Example:
Photodiode Responsivity
RESP(?)
{
f
}
Set (query) the monitor photodiode responsivity
{
to
f
}
, in
μ
A
/
mW.
The responsivity determines the conversion from photodiode current
(in
μ
A) to optical power (in mW). The minimum possible value for
RESP
is 0.0051
μ
A
/
mW.
Changing the value of
RESP
, either directly or through the
CALP
command, will cause indirect changes to either
SIPD
and
PILM
(if
PDMW
YES
), or
SWPD
and
PWLM
(if
PDMW
NO
). This is because the
LDC500 always enforces the two relationships
SIPD
=
SWPD
×
RESP
and
PILM
=
PWLM
×
RESP
Note that the responsivity cannot be changed while the laser is on,
and in CP control mode, and in mW units (
PDMW
YES
).
Front panel:
LD :#/
,*>-
.
RESP?
Example:
1.000
LDC500 Series Laser Diode Controllers
