1) We strongly recommend using only NiCad C -cell
rechargeable batteries. Alkaline batteries may leak and destroy
the meter if left installed or if accidentally charged. You can
buy NiCad rechargeable batteries locally or purchase our
rechargeable batteries (A417)that have been proven to operate
for over 10 years without any damage due to leakage. When a
nickel cadmium battery goes dead, it does not destroy the life
of the battery. In fact it is a good idea to run NiCads down
to the low limit on occasion, to prevent a charge
‘memory’
effect
2) If operation is required outside the United States, be
sure to check the voltage switch before putting 230 volts
into the line cord.
3) Shipping can be a problem if the internal batteries
are left inside the instrument. The high
‘G’
forces
associated with a dropped carton, can dislodge a battery that
can thereby become destructive to the circuitry inside.
4) Another suggestion regarding shipping. Always ship
instrument in A405 case, with additional padding.
We have
found damage to circuitry even though the shipping carton
shows no obvious abuse on the outside. This happens
because a lack of packing forces the instrument to decelerate
at such a high rate, that P.C. boards etc. can become
dislodged.
5) Be sure to check the zero if you are in doubt about
when it was last set. The zero level is remembered
after the power is turned off. The previous user may have
set it to subtract a very high level, which will produce
erroneous results for your next measurement.
6) Be careful when measuring UV sources. There are
many industrial uses for Ultraviolet light, in UV curing,
Photo Resist exposure systems, Printing plate lithography,
etc. Proper goggles should be worn that absorb the UV. If
in doubt, we offer UV rejecting sun glasses (A26) that are
specifically designed to block out all UV.
8. Applications
8.1 Current and Conductance Measurem ents
Most light detectors have a linear relationship between
the incident irradiance and a current output, as long as the
device is biased correctly. For this reason the ILT1700 is a
very sophisticated , programmable, current and conductance
measuring instrument. Current is measured in the units of
Amperes, while conductance is measured in units of
Siemens, where a Siemen is the reciprocal of the resistance
unit know as the Ohm. There are many other types of
transducers that also have an output which is a change of
current or conductance. These devices cover measurements
in the fields of temperature, pressure, humidity, ionizing
radiation, Ph, Voltage, weight, magnetic force, and so on.
Since the instrument can be programmed to make the input
stimulus read directly in recognized units, it becomes very
useful for many other applications above and beyond the
measurement of optical radiation.
20
The ILT1700 has one of the largest dynamic ranges of
any instrument on the market. It will read to better than two
digit resolution, from 1e
-12
to 2e
-3
Amperes and read
conductance from 2e
-13
to 4e
-4
Siemens (formerly mhos),
each of which cover more than nine (9) decades. In
addition, it has the ability to integrate these signals from
microsecond speeds to 18 years.
8.1.1 Polarity
Most light sensitive devices can be configured to
produce a negative current (positive electron flow) easier
than a positive current. This is especially true of
vacuum photodiodes. Also, one of the simplest detector
configurations uses a detector into an operational amplifier,
configured in the transconductance mode , to produce a
positive output voltage. For this reason, we have chosen to
measure negative current from the sensitive input pin 6 with
respect to instrument signal ground (pin 7), or with respect to
the input guard voltage (pin 9 called
‘bia
s
common’)
, which
stays at the same potential as the input even if you apply the
5V BIAS. In other words, by turning on the 5V BIAS, the
input (pin 6) and the guard (pin 9) will rise up to +5 volts,
with respect to the instrument ground (pin 7). This input
configuration permit s front panel bias selection for a two
terminal device, using the input and the ground. It also
allows for a coaxial shield connection at the input potential,
using a three wire configuration . This eliminates the
shielded cable leakage current. The 3 wire configuration is
necessary for measurement s below the nanoamp range.
8.1.2 Input Cable
As described above in section 8.1.1, the three pins that
are used for current or conductance, are pins 6,7 & 9, which
are the input, ground, and input guard (or bias common),
respectively.
8.1.3 Overload
In order to protect the IL1700 we have designed the input
to take a great deal of overload. There is a limit, however, due
to the sensitive nature of the measured signals. It is impossible
to completely protect the input from every kind of abuse.
Generally speaking, the input will take about 100 milliamps,
either positive or negative current, from DC to 100mHz, for a
short time (about 5 seconds). The input will also survive
voltages of approximately plus or minus 15 volts for a similar
short time durations. This type of protection offers good survival
to most modern circuit accidents, and is designed to withstand
more R.F.(radio frequency) pick up that may be present in
typical user environments. One of the most common R.F.
sources is the igniter for arc lamps. These lamps generate about
30,000 volts at about 1 MHz, during ignition. The induced
radiation from this process, has been known to destroy volt -ohm
meters and other instruments, even when they are not p lugged
into anything. The coupl ing is strictly radio frequency
transmission to a nearby circuit. This type of damage is not a
rare occurrence. If you operate many arc lamps, as we do in our
calibration lab, you will find that these problems arise . Since
we have had a personal intere st in withstanding this kind of
damage, we have gone to a great extent to design the proper
protection into the ILT1700.
代理美国International Light辐照计http://www.testeb.com/yiqi/ilt/zhaoduji.html 深圳市格信达科技 电话18823303057 QQ：2104028976
