Overview
Program for calibrating photodiode-related settings.
File>Open
n/a
Name
The name of the photodiode device; a default name is provided.
BoardID, ChannelID
Self-explanatory.
Lens, Transmission
Select the appropriate lens from the drop-down list. Enter a value for the transmission (T%) of the lens, for the wavelength of interest.
Although lens manufacturers may supply the T% (usually in the form of a spectrum), it is usually more accurate to measure the transmission for each lens for the specific wavelength of interest. This can be done as follows: (1) with the beam intensity reduced sufficiently to avoid damaging the lens, measure the the beam intensity after the objective lens; i.e., place a power meter directly in front the the lens. Note that the meter should be pressed against, or otherwise very close to, the lens such that all the light hits the sensor. (2) Now take the lens off, obtaining a measure of the beam intensity before the lens. The ratio (after/before) gives the T%.
Known bug: on re-loading the photodiode configuration, the lensTransmission value will be displayed (incorrectly) as 100%, instead of the (correct) value that was entered by the user. However, the correct value will be used to determine the nominal light intensity at the specimen plane, as displayed in the Mapper gui.
Calibration Panel
Enter user initials in the 'User' window. The date window is auto-filled. To calibrate the photodiode, hit the 'Clear' button if there was a previous calibration, then input the power level at the back focal plane (typically determined by removing the objective and placing a power meter in front of the beam). Do this for several power levels, being sure to include levels that are around those that will be used in experiments (for example, if you do experiments at 20 mW, include calibration points in the range 20 +/- 5 mW). The graph shows a plot of the power (input by the user) versus the photodiode voltage (obtained by sampling the photodiode current at the time of entering data in the 'mW' window).
Note
Remember to save the calibration data -- i.e., File>Program Manager>Save Configuration