The graphs below show examples of the measured instrument response functions (IRF) of a PDM module with an active area of 50 µm. The measurements were done with the PicoHarp 300 and different laser heads of the LDH series driven by the PDL 800-B.

The measured full width at half maximum (FWHM) is 48 ps for the excitation at 670 nm. Taking the exceptionally short pulse width of the excitation laser of 32 ps into account, this results in a timing response of the SPAD of 37 ps.	The measured full width at half maximum (FWHM) is 84 ps for the excitation at 635 nm. Taking the pulse width of the excitation laser of 66 ps into account, this results in a timing response of the SPAD of 50 ps.
The measured full width at half maximum (FWHM) is 72 ps for the excitation at 470 nm. Taking the pulse width of the excitation laser of 56 ps into account, this results in a timing response of the SPAD of 44 ps.	The measured full width at half maximum (FWHM) is 224 ps for the excitation at 405 nm (laser pulse width: 60 ps). Such an increase of the IRF at blue/UV wavelengths is typical for these SPADs.