How do I calibrate my TILL Photonics Polychrome monochromator in Openlab?

Technical Note: 18
Reads: 8987
Creation Date: 30/11/1999
Modification Date: 12/02/2004

Method 1: Kit includes black photodiode with rotatable filter holder

Switch on the Polychrome II for at least 20 minutes before attempting the calibration.

The Polychrome II is supplied with two filters (380 and 505 nm), a photodiode and a digital voltmeter.

Place the 380nm filter (blue surface) and the 505nm filter (silver surface) into the filter holder with the mirrored surfaces towards the incident light and rotate the filter holder such that the 380nm filter is positioned above the photodiode.

Connect the red lead from the photodiode to the RED VWmA socket on the voltmeter.

Connect the black lead from the photodiode to COM socket on the voltmeter.

Set the DC voltage range on the voltmeter to 2000m.

Position the optical fibre so that it shines directly onto the 380nm filter and select 380nm on the Openlab Polychrome palette.

Start the calibration process by clicking on ‘Calib’ on the Polychrome palette.

Press the ‘Reset’ button to remove any previous settings.

Note the value of the DC voltage as indicated by the digital voltmeter.

Now click on the small left and right arrows on the Polychrome palette to increase or decrease the value of the Polychrome wavelength in 1nm steps. Continue to adjust this until the peak voltage is reached as indicated by the voltmeter reading.

When the peak voltage has been achieved, click on the 'Calib' button again and enter '380' in the true current wavelength box. Click on 'OK'.

Now rotate the filter holder so that the 505nm filter is above the photodiode. Select 505nm from the Polychrome palette and repeat the process above.

Entering the calibration value for this second position calibrates the Polychrome II and it is now ready for use.

Method 2: Calibration Kit includes cylindrical silver device with built in triple pass filter

Switch on the Polychrome II for at least 20 minutes before attempting the calibration. It is best to have centred the lamp before calibrating. See the manual supplied with the equipment for more details.

The calibration kit includes:1x Calibration device with triple pass filter for 398, 469 and 586 nm. 1x Adapter - BNC to 4mm screw down Black and Red jack posts.1x Voltmeter with milli voltage range.1x Set of voltmeter leads.

Remove the red fibre optic light guide from its connection point on the front of the polychrome light house and replace it with the cylindrical silver calibration device. Attach the adapter via the BNC connection.

Connect the red voltmeter lead from the RED VWmA socket on the voltmeter, and clamp the test probe on the other end in the RED screw down jack post.Connect the black voltmeter lead from the photodiode to COM socket on the voltmeter, and clamp the test probe on the other end in the BLACK screw down jack post.

Set the DC voltage range on the voltmeter to 2000m.

Select 398nm on the Openlab Polychrome palette. Start the calibration process by clicking on 'Calib' on the Polychrome palette.Press the ‘Reset’ button to remove any previous settings. Note the value of the DC voltage as indicated by the digital voltmeter.Now click on the small left and right arrows on the Polychrome palette to increase or decrease the value of the Polychrome wavelength in 1nm steps. Continue to adjust this until the peak voltage is reached as indicated by the voltmeter reading.When the peak voltage has been achieved, click on the 'Calib' button again and enter '398' in the true current wavelength box. Click on 'OK'.

Now select 586nm from the Polychrome palette and repeat the process above.Entering the calibration value for this second position calibrates the Polychrome IV and it is now ready for use.

(The center wavelength of 469nm is not used)

Detach the calibration device from the lamp house and replace the red light guide.