INTEGRATING SPHERE TECHNOLOGY

The integrating sphere is a fundamental optical technology, commonly used in photometry and radiometry, for applications including the test and measurement of light sources (lamps, LEDs, Lasers, fiber-optic illuminators), sensors (focal-plane arrays, spectrometers, and camera systems), and material properties (reflectance and transmittance).

Description: In the most general terms, an integrating sphere consists of a spherical shell, with a diffuse white (and therefore highly reflective) optical coating on its inside surface. Ports or apertures in the sphere wall admit or release light, which undergoes multiple diffuse reflections within the sphere cavity. Such reflection serves to spatially homogenize the light passing through the sphere, attenuating the optical signal significantly in the process. Typically, one or more baffles within the sphere cavity are positioned strategically to shield system components from undesired direct illumination, thereby enhancing sphere performance.

Purpose: Though specific attributes vary with application, an integrating sphere is generally used to perform the following functions:

• Collection of Light - from some type of source
• Spatial averaging (homogenization)
• Illumination - of some type of sensor or specimen

Key Design Specifications:

• Sphere diameter
• Number of ports
• Port dimensions and location
• Baffle position(s) and function(s)
• Mechanical interfaces: Port adaptors, mounting fixtures, etc.

Key Performance Specifications:

• Spectral reflectance of coating
• Thermal and environmental stability of coating
• Uniformity/Homogeneity
• Attenuation or efficiency