THORLABS EVOA800A, Руководство пользователя

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Electronic Variable Optical Attenuators Chapter 4: Operating Instructions & Details
Rev A, November 14, 2016 Page 9
Follow these simple steps to calibrate the USER position:
1. Switch the wavelength selector knob to the USER position.
2. Send an optical input into the input bulkhead at the wavelength of
interest. We recommend an input power of a few mW for the best
accuracy.
3. Rotate the manual power adjustment knob completely clockwise to
set it at minimum attenuation.
4. Attach the power meter to the output fiber patch cable. (Make sure
the power meter is set to the correct wavelength.)
5. Adjust the user calibration trimpot so that the power value on the
digital display agrees with the value shown on the power meter.
6. At this point, we recommend making a note of the user wavelength
and placing a piece of tape over the trimpot to prevent accidental
adjustments.
4.5. Attenuation Control
The user can control the attenuation using two analog methods.
The first and simplest method is to rotate the manual power adjustment knob
on the front panel (see Figure 1). This knob provides the full range of
attenuation. Rotating it clockwise increases the output power, while rotating it
counterclockwise decreases the output power. The knob has ten full rotations.
The second method is to apply a voltage to the SMA modulation input on the
side utility panel (see Figure 3). This input allows for modulation from DC to 1
kHz. See Section 4.7, Modulation Input & Monitor Output Connections, for
details.
4.6. Digital Output Power Display
The digital output power display uses the signal from the tap output (see
Section 4.1) to calculate the calibrated output power before the tip, in mW, at
785 nm, 852 nm, or the user wavelength. The display offers 4.5 digits of
resolution (the leftmost digit has a maximum value of 1). The display range
will auto-scale for low or high input power, and changes over at about 15 mW.
The digital display also has a Low Battery warning that indicates when the
battery needs to be charged. The warning appears while there is still sufficient
charge remaining for the Li-ion battery not to degrade.
4.7. Modulation Input & Monitor Output Connections
The side utility panel (see Figure 3) provides two SMA connectors: an input
for analog modulation and an output for power monitoring.