The lamp position influences the luminous flux
LED lamps are often manufactured with integral driver circuitry. This means that the lamp orientation (base up, base down, etc) can have a significant effect on the junction temperature of the LEDs due to the different heat flow scenarios. Luminous flux, spectrum and color are directly related to junction temperature. The lifetime of LEDs is also reduced as junction temperature is increased. The measurement of photometric properties of LED lamps operating in the different orientations is therefore highly recommended. The ISD-100HFT-BTS2048-VL light meter from Gigahertz-Optik is a high-quality, CCD-based spectroradiometer with a rotatable, 100cm diameter, integrating sphere. This combination can be used to measure the luminous flux, spectrum, color, and color rendering index of LED lamps operating in any orientation.
The BTS256-VL light meter
The high-quality BTS2048-VL CCD based spectroradiometer is internationally recognized as a high-end product. It is one of the most compact spectroradiometers on the market which enables direct system integration in many applications without the need for expensive, and potentially measurement degrading, light guides. Among its characteristic features is its diffusor window with cosine corrected field of view for the measurement of spectral irradiance and spectral illuminance. This also permits direct mounting onto integrating spheres (e.g. the ISD-100HFT) for measurement of luminous flux. More detailed information about the BTS2048-VL can be found in the respective data sheets. The unit is also available in the BTS2048-VL-TEC thermoelectric cooled version.