Optical Calibration
Use the Optical tab of the Calibrations dialog to calibrate an optical input channel on modules installed in a N1000A's module bay as well as DCA-M modules. Click Tools > Calibrations to open this dialog.
The Optical calibration tab is shown whenever an optical module is installed.
For a N109X-series DCA-M modules and modules installed in a N1000A's module bay, you can use this tab to perform optical calibrations at both factory and user wavelengths. If you perform an optical channel calibration at a factory-calibrated wavelength, the factory calibration will not be overwritten. The calibrations for two-slot modules are stored on the N1000A's hard drive and not on the module. The following picture shows the dialog tab with the state of the calibrations.
Some older installed modules, such as the 86105C, do not support a user factory calibration.
Factory and user optical channel calibrations (also known as O/E calibration) compensate for the photo detector responsivity. This provides both an accurate display of the received optical waveform in optical power units and an accurate measurement of the signal's average power. If you will be operating at wavelengths different from the factory-calibrated wavelengths, perform a user optical channel calibration at the desired wavelength. An external CW optical source must be used, and the wavelength and power of the optical source must be entered for the calibration. The user-defined wavelength must be within the wavelength ranges specific to each module. For example, if you are operating the N1090A DCA-M module, you can select a user-defined wavelength between 750 nm and 1650 nm. The power output from the optical source must also be within the ranges specific to each module.
You can create up to three user calibrations: User Cal 2, User Cal 3, and User Cal 4. Stored user calibrations can be deleted from memory using by clicking the Clear button.
Do not remove a module from the N1000A during a calibration.
| Icon | Description |
|---|---|
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Calibration is selected |
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Calibration is unselected |
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Calibrations are partially selected |
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Calibration is current |
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Calibration is recommended |
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Calibration has never been performed |
To perform an optical channel calibration, an optical source with a known optical output power level is required.
The minimum power level is recommended to assure specified performance over the instrument's full dynamic range. The calibration accuracy is heavily dependent on the accuracy to which you know the optical source power. For best results measure the optical source power with a high precision optical power meter.
If the result for an average power measurement (either eye/mask mode or oscilloscope mode) is an extremely large value, the instrument may have lost the factory optical channel calibration. For example, a value of 260W may be displayed for a 100 μW signal. You can also perform an optical responsivity calibration for a user-defined wavelength.
| Module | Calibrate From | Factory Calibrated Wavelength(s) |
Source Optical Power Level | ||
|---|---|---|---|---|---|
| FlexDCA | N1000A | Allowable | To Meet Specifications | ||
| N1092A/B/C/D/E | ♦ | 850 nm 1310 nm 1550 nm |
500 μW to 2.5 mW 500 μW to 2.5 mW 500 μW to 2.5 mW |
500 μW to 1 mW 500 μW to 1 mW 500 μW to 1 mW |
|
| N1090A | ♦ | 850 nm 1310 nm 1550 nm |
375 μW to 425 μW 175 μW to 225 μW 175 μW to 225 μW |
375 μW to 425 μW 175 μW to 225 μW 175 μW to 225 μW |
|
| 86116C | ♦ | 1300 nm 1620 nm |
500 μW to 6 mW 500 μW to 6 mW |
500 μW to 6 mW 500 μW to 6 mW |
|
| 86115D | ♦ | 850 nm 1310 nm 1550 nm |
800 μW to 2000 μW 500 μW to 1500 μW 500 μW to 1500 μW |
800 μW to 1500 μW 500 μW to 1000 μW 500 μW to 1000 μW |
|
| 86105D | ♦ | 850 nm 1310 nm 1550 nm |
800 μW to 2000 μW 500 μW to 1500 μW 500 μW to 1500 μW |
800 μW to 1500 μW 500 μW to 1000 μW 500 μW to 1000 μW |
|
| 86105C | ♦ | 850 nm 1310 nm 1550 nm |
375 μW to 425 μW 175 μW to 225 μW 175 μW to 225 μW |
375 μW to 425 μW 175 μW to 225 μW 175 μW to 225 μW |
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