How to Select and Size an Integrating Sphere
In order to select the Spectral Products Integrating Sphere that is best suited for your application, several factors must be taken into consideration. The most important factors include the following:
Diameter/Source Ratio: The diameter of the sphere should be at least 1.5 times the largest dimension of any device mounted within the sphere.
Surface-to-Port Area: If ports cover more than 5% of the Integrating Sphere's surface, the Integrating Sphere may not integrate properly. If port requirements are greater than 5% of the sphere, a larger sphere should be purchased.
The following formulas can determine port area and sphere surface area:
- r = Port radius
- D = Sphere Diameter
Port Area = pr2
Sphere Surface Area = 4pD2
Integrating Sphere Coatings: The coating of a Spectral Products Integrating Sphere is a high efficiency diffuse reflector that delivers reliable integration and low throughpit loss. The reflectance is high in order to minimize absorption loss from multiple relfections, yet it must not reflect light specularly.
Spectral Products' Integrating Sphere Coatings offer reflectance efficiencies between 95% to 99%. A Lambertian Source is a perfect diffuse source. When a perfect diffuse reflector is illuminated with uniform intensity, it acts as a Lambertian Source. Spectral Products uses a proprietary Ba2SO4 coating, effective from 380 up to 2,400nm, to provide these state-of-the-art Lambertian properties.