will be reset as soon as the power is turned off. The
ILT1400 will then restore the original values from the
detector EEPROM when turned on. When the automatic
shut-off has been disabled, the instrument will blink the
message ‘NO OFF’ in the status register of the LCD during
‘SIGNAL’ mode, shown above. Since the ILT1400 is
programmed to allow integration for as long as necessary to
complete a measurement, the instrument will never
automatically shut off while actively integrating.
‘ENABLED (10 min)’ is the standard mode of
operation, causing the instrument to automatically shut off
if a keypress is not sensed within 10 minutes while in
‘SIGNAL’ mode. As mentioned above, while in
‘INTEGRATE’ mode, the ILT1400 will operate indefinitely
without shutting off to provide for long term integration
measurement sessions. However, if ‘HOLD’ is pressed
while in ‘INTEGRATE’ mode, the instrument will
automatically shut off in 10 minutes. Remember to hit
‘ENTER’ to permanently enable (or disable) the automatic
shut-off feature.
‘DISABLED (temp.)’ causes the instrument to
TEMPORARILY disable the automatic shut-off. This
particular selection does not need to be ‘ENTERed’, since it
is inherently a temporary change and will not be stored in
the detector EEPROM. The instrument will reset to the
previously established mode when the power is lost.
‘DISABLED (PERM.)’ causes the instrument to
PERMANENTLY disable the automatic shut-off, until this
feature is enabled again in program mode. Remember to hit
‘ENTER’ to permanently disable (or enable) the automatic
shut-off feature.
6.3 Changing the Displayed Units
WARNING: CHANGING THE DISPLAYED UNITS
MERELY CHANGES THE WORD, NOT THE ACTUAL
READING. THE READING MUST BE SCALED BY
CHANGING THE SENSITIVITY FACTOR. YOUR
INTERNATIONAL LIGHT CALIBRATION IS VALID
ONLY FOR THE SENSITIVITY FACTOR AND UNITS
SPECIFIED ON YOUR CALIBRATION CERTIFICATE.
Press the ‘MENU’ (ZERO) button to scroll to the
‘UNITS SELECTION’ menu screen. Use the ‘SELECT’
(SIGNAL) button to choose ‘UP’ or ‘dn’, changing the
direction that you scroll in the list of units. Press the
‘INCREMENT’ (INTEGRATE) button to scroll to the next
set of units in the up or down direction. Press the ‘ENTER’
(HOLD) button when you have selected the proper units if
you would like the change to be stored permanently on the
detector EEPROM. Please note that changing the displayed
units merely changes the word portion of the display. The
numerical readout will not be converted to the new units
(except for unity conversions such as lm/m2 to lux, etc.).
The mathematical conversion can, however, be accomplished
by changing the sensitivity factor.
6.4 Changing the Sensitivity Factor
WARNING: THE N.I.S.T. TRACEABLE
CALIBRATION PROVIDED BY INTERNATIONAL
LIGHT WITH YOUR ILT1400 IS VALID ONLY FOR THE
SENSITIVITY FACTOR AND UNITS SPECIFIED ON
YOUR CALIBRATION CERTIFICATE. ALL
CALIBRATION FACTORS REQUIRE THE USE OF THE
EXACT COMBINATION OF SENSOR, FILTERS AND
INPUT OPTICS THAT WERE USED DURING
CALIBRATION.
We have designed the ILT1400 to accommodate the
diverse needs of our customers. Our calibrations ensure
N.I.S.T. traceable accuracy in absolute optical units. Since
we recalibrate the complex electrical circuitry of our
instruments before recalibrating to the N.I.S.T. optical
D.R.I.P. standard, we recommend recalibration only by
International Light Technologies. We do recognize,
however, that some customers require the capability to
optically self calibrate their own detectors to an in-house
standard or to simply read the absolute current output of a
detector in Amperes. Some users may also want to change
back and forth periodically between the English and SI units
systems. For these reasons and many more, we allow the
EXPERIENCED USER the versatility to change the
sensitivity factor that determines the reading displayed on
the instrument.
The ILT1400 accurately measures over seven decades of
low level current changes, from 10 picoAmperes to 350
microAmperes. The instrument is electronically calibrated
to measure this current absolutely, in Amperes. The detector
head is then calibrated in our labs against a N.I.S.T.
traceable optical standard to obtain a sensitivity factor, in
Amperes per desired Optical Unit, such as 1.876 x 10
-3
Amps/Watt/cm
2
.
The ILT1400 divides the measured current reading by
the sensitivity factor to render an answer in the desired
optical units. Naturally, the sensitivity factor for direct
readout in Amperes is 1.000 x 10
0
Amps/Ampere, a unity
conversion factor.
Self calibrating an ILT1400 to an in-house standard is
remarkably easy to accomplish. The instrument displays the
ongoing signal reading even as the sensitivity factor is
incremented. This allows the user to adjust the reading to an
established optical standard in real time. For example, the
sensitivity factor can be adjusted until the reading agrees
with a previously calibrated detector’s output. For
production environments, the reading can be adjusted to an
arbitrary number, such as 100.0, that relates to the maximum
output of a lamp standard. Readings would thereafter be
displayed in percent.
19
+123.4 lm/m2
UNITS SELECT UP
+123.4 lux
UNITS SELECT dn
Содержание ILT1400
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