Implementation of a measurement system for analysing the spectral radiation pattern of light sources with low divergence

Abstract

For the verification of Free Space Optics (FSO) systems it is common to determine optical power measured depending on illuminated area at a certain wavelength. In the context of this work a new measurement system was developed, which is able to measure not only the optical power but also the complete spectral distribution of the light beam. FSO is becoming more and more important, because of the high usable bandwidth (leading to high data-rates) in optics compared to radio frequency (RF). The measurement system consists of a mechanical structure, where a collimator is mounted on. This collimator can be moved in two dimensions to enable the measurement of predefined points. It is connected with a spectrum analyzer using an optical fiber. A computer controls the position of the collimator and initiates the spectrum analyzer to record the spectral curves, the maximum peak of power, the -3dB bandwidth and the total power of spectrum. The obtained data covers a measurement area of 0.91 m by 0.77 m which can be surveyed at a high local resolution of 0.7 mm. Collimated beams in the range between 600 and 1750 nm are analysed.