Troubleshooting Tips: Radiometric LED Measurements
Here are some useful tips and other information to guide you through your LED measurements:
Calibration sources, lifetime of. Radiometric calibration sources must be recalibrated after 50 hours of total operation (“on”) time. Usage should be logged so the lamp can be returned to Ocean Optics for recalibration as needed.
Irradiance calibration, spectral splicing of. OceanView software has the capability to splice calibration files together. This function is for users who have a radiometrically calibrated DH-2000-CAL deuterium-tungsten halogen light source, which comes with two separate lamp files and requires the user to calibrate the spectrometer separately for the UV and Visible ranges. If you want to generate one continuous calibration, you can use the Combine Calibration option from the File | Tools menu to combine the files into one calibration file.
Irradiance, power per unit area. Irradiance measures how much power is hitting or passing through a unit area. Angles do not matter. Essentially, irradiance is the intensity of the light source on that surface.
LEDs and temperature. An LED’s center wavelength and wavelength shape can change with drive current or temperature. The figure below shows a fiber-coupled 455 nm LED at various drive currents, measured with an HR-series spectrometer.
Radiometric calibration services, ordering tips for. Irradiance calibration of a system is valid only as long as the components remain connected. Parts will be cemented with Loctite or similar adhesive to prevent disconnection. When ordering, please specify the assembly to be calibrated:
- Spectrometer and fiber
- Spectrometer, fiber and integrating sphere
- Spectrometer, fiber and cosine corrector
- Spectrometer and fiber and/or lens; any combination requires a custom calibration procedure, at additional cost