LED source provides sensor with self-absorption correction

Posted By : Siobhan O'Gorman
LED source provides sensor with self-absorption correction

Designed for optical power measurement, the 3A-IS Optical Power Sensor and AUX-LED Self-Absorption Accessory have been released by Ophir Photonics. The 3A-IS is an integrated sphere and photodiode sensor system which can measure the optical power of divergent, narrowband light sources from 350 to 1100nm, such as lasers and LEDs. The AUX-LED is a current regulated LED source which corrects the effects of self-absorption.

The 3A-IS, which utilises two 40mm spheres and a photodiode detector, has a reduced light intensity, enabling the measurement of powers up to 3W. When measuring UV-LEDs operating in the 365-400nm range, the AUX-LED provides self-absorption correction. On request, additional AUX-LED wavelengths are available for specific UV, visible, and IR wavelengths. 

When using the 3A-IS for measuring narrowband sources with a known wavelength, the auxiliary lamp should also have the same spectral characteristics as the device being tested. For a specific wavelength band such as UV-LEDs at 365-400nm, the AUX-LED replaces a wideband auxiliary lamp with an LED.

The 3A-IS features a 'smart connector‘ interface which is compatible with Ophir Photonics‘company's StarLite, Nova II, and Vega smart displays, and Juno PC interface. When plugged into one of the company's laser measurement heads, the display is automatically configured and calibrated.

"Self-absorption in integrating sphere measurements is a well-known issue," commented Dr. Efi Rotem, Project Manager, Ophir Photonics. "The device under test disturbs the geometry and throughput of the sphere by absorbing or reflecting some of the light inside, which causes a measurement error. This problem is solved using an auxiliary lamp installed inside the sphere. Measurement of the auxiliary lamp before and after the device under test is in place enables self-absorption correction. Spectrometer based systems require a wide band auxiliary lamp such as a tungsten lamp to cover the entire spectral range of the spectrometer."

The 3A-IS Optical Power Sensor and AUX-LED Self-Absorption Accessory are available now.


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