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.

For a N109X-series DCA-M modules and N1000A plug-in modules, you can use this dialog tab to perform optical calibrations at both factory and user wavelengths. Factory and user optical channel calibrations (also known as O/E calibration) compensate for the photo detector's 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.

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 picture above shows the dialog's optical tab with the state of the calibrations.

You can create up to three user calibrations: User Cal 2, User Cal 3, and User Cal 4. To delete a user calibrations from memory click the Clear button.

Required External CW Optical Source

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 as shown in the table below. 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.

Minimum Power is Recommended

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.

To Perform an Optical User Calibration

1. On FlexDCA's menu, click Setup > Modules and select the module that you want to calibrate.
2. In the Setup dialog, select the tab that represents the channel that you want to calibrate.
3. Locate Wavelength field in the dialog. This drop-down list is where your user calibration will appear once you have completed this procedure.
4. Configure an external CW optical source to the wavelength and power that is compatible with the module as shown in the following table.
5. Disconnect all signal from the module's input channels. FlexDCA will prompt you to connect your calibration signal during the calibration.
6. On FlexDCA's menu, click Tools > Calibrations to open the Calibrations dialog and select the Optical tab.
7. Locate the Channel User Optical Calibration listing in the dialog and click Calibrate.
8. As part of the user optical calibration, a dialog will prompt you to perform a Module Calibration. Click Next. During the Module Calibration, no signals can be connected to the input channel.
9. After the Module Calibration completes, a channel Vertical Calibration automatically starts.
10. After the Vertical Calibration completes, FlexDCA displays the Channel User Optical Calibration dialog. In the dialog, make the following selections:
• Click the Selected Calibration drop-down list and choose User Cal 1, User Cal 2, or User Cal 3.
• Click the Wavelength field, and enter the wavelength of your optical source.
• Click the Average Power field, and enter the average power of your optical source.
11. Click Next to complete the user wavelength calibration.

Optical Calibration Requirements

Module	Option	User Calibration Wavelength Range	Factory Calibrated Wavelength(s)	Source Optical Power Level
				Allowable	To Meet Specifications
N1092A/B/C/D/E	30A	830 nm to 1600 nm	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
N1092A/B/C/D/E	40A	1250 nm to 1600 nm	1310 nm 1550 nm	500 μW to 2.5 mW 500 μW to 2.5 mW	500 μW to 1 mW 500 μW to 1 mW
N1092A	N28	830 nm to 1600 nm	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		750 nm to 1650 nm	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
N1032A/B		1250 nm to 1625 nm	1310 nm 1550 nm	175 μW to 225 μW 175 μW to 225 μW	175 μW to 225 μW 175 μW to 225 μW
N1030A/B		1250 nm to 1600 nm	1310 nm 1550 nm	175 μW to 225 μW 175 μW to 225 μW	175 μW to 225 μW 175 μW to 225 μW
86116C		1480 nm to 1620 nm	1550 nm	500 μW to 6 mW	500 μW to 6 mW
	025	1300 nm to 1620 nm	1300 nm 1550 nm	500 μW to 6 mW 500 μW to 6 mW	500 μW to 6 mW 500 μW to 6 mW
86115D		750 nm to 1650 nm	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		750 nm to 1650 nm	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		750 nm to 1650 nm	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