Integrating Sphere Photometric System

Definition & Scope

An integrating-sphere photometric system typically combines a sphere, array spectrometer, precision power supply, and electrical meter. Inside a near-Lambertian cavity it collects flux and yields SPD, chromaticity, CCT, CRI/TM-30 metrics, and color tolerance. Applications include LED packages/modules, luminaire photoelectric tests, and compliance work such as LM-79 and energy-label measurements. BaSO4 coatings suit visible work; PTFE is preferred for UV and demanding spectral ranges.

FAQ

How do I choose sphere diameter?

Diameter must exceed the emitting size and support self-absorption correction. Small LEDs can use smaller spheres; large luminaires need larger diameters with auxiliary-lamp correction and proper port geometry.

BaSO4 vs PTFE integrating spheres?

BaSO4 is common for visible photoelectric tests; PTFE is preferred for UV/deep-UV or higher reflectance stability. Follow the spectral range and calibration chain.

What instruments complete a sphere system?

Typically an array spectrometer (e.g. SPM-5000/8000), AC/DC precision supplies (APS/DPS), and an electrical meter (e.g. PM310H) so optical and electrical data are synchronized and traceable.

Can a sphere replace a goniophotometer?

No. Spheres are fast for total flux/color but do not provide full spatial distribution. Intensity curves, IES/LDT files, or UGR still require a goniophotometer.