Newport 8000 - Page 99

86 Chapter 6 Calibration
read the termperature as a constant 25°C. Setting a temperature of 20°C and 30°C
with the output on will force it to go to the positive and negative limit, respectively,
allowing the limit set point to simulate an I
TE
current set point.
a. Connect a 10 kΩ resister across the sensor input. With the output off,
connect a 1 Ω, 50 W resistor and a calibrated ammeter in series across
the laser output terminals. If an ammeter with the appropriate current
ratings is unavailable, connect a 1 Ω, 50 W resistor across the laser
output terminals and use a calibrated DMM to measure the voltage
across the resistor. Calculate the current in the following steps by using
Ohm's Law:
I = V / R
where V is the measured voltage across the resistor, and R is the
measured load resistance.
b. Enter the
TEC:CHAN
command to select the channel [,suchannel] to
be calibrated. Send
TEC:CAL:ITE
to enter I
TE
calibration mode.
The 8000 will select the Thermistor sensor and place the system in
constant temperature mode. The I
TE
current limit is set to 50% of full
scale, and the output turned on.
The 8000 will be ready to receive the first measured current value
when, after a
TEC:CAL:ITE?
query is sent, a “1” is returned.
c. Input the actual current (as an <nrf value>) via the
TEC:ITE <nrf
value>
command. The 8000 will then drive the current to 25% of the
initial set point. The 8000 will be ready to receive the second measured
current value when, after a
TEC:CAL:ITE?
query is sent, a “1” is
returned.
d. Input the second actual current (as an <nrf value>) via the
TEC:ITE
<nrf value>
command. The 8000 will then drive the current to the
negative current value of the initial set point. The 8000 will be ready to
receive the third measured current value when, after a
TEC:CAL:ITE?
query is sent, a “1” is returned.
e. Input the third actual current (as an <nrf value>) via the
TEC:ITE <nrf
value>
command. The 8000 will then drive the current to 25% of the
negative current value of the initial set point. The 8000 will be
ready to receive the fourth measured current value when, after a
TEC:CAL:ITE?
query is sent, a “1” is returned.
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