Integrating sphere photometers are simple systems to measure the total luminous flux. However, the issue of self-absorption exists especially for LED measurement. For example, a high-power LED includes parts other than the light emitting point in the integrating sphere, such as a large heat sink and electric circuit module. As a solution, we introduced the integrating hemisphere for the measurement of the total luminous flux of these devices. The integrating hemisphere was composed of a hemisphere whose inside wall was coated with BaSO
4 and a high reflectance mirror, which was installed along the equatorial plane. The light source under test was set inside the hemisphere near the central part of the mirror. The spherical integration surface consisted of the real image on the integration hemisphere side and the virtual image on the mirror side because the light source was set up at the center of the mirror that was arranged in the equatorial plane. One of the advantages was that only the light source sat inside the integrating hemisphere while the lamp supporter, driving devices and other parts were outside. Even for the measurement of a high-power LED installed in a temperature control module with a large heat sink, only the illuminant part is in the integration space. Moreover, its emitting part was located at the center of an ideal integration space by the virtual image from the mirror. As a result, the self-absorption of the sample was be significantly reduced.
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