In the optical field, it is very necessary to use an integrating sphere to measure the intensity of the incident beam. In the actual measurement, however, there exists an illogical situation with the perfect integrating sphere as an optical reflecting diffuser that the measured values of the illumination are different. In order to explain this situation, the model of the relationship between the incident beam geometry and the output illumination of the integrating sphere was developed and a simulation experiment was conducted. The simulation error of the transmittance, with a 300 mm diameter and 3% core-opening ratio, could reach 0.5% when the incident beam geometry changes. The experimental results and analysis show that the random change of the escaping ratio of the luminous flux was caused by the random position and distribution of the spot, which is the main source of the illogical situation. It provides theoretical guidance to the integrating sphere based on optical measurement.
© 2018 Optical Society of AmericaPDF Article