Integrating sphere or Ulbricht sphere as it is also called is an optical facility in which the interior is covered with diffuse reflectors. It has holes used as for external and internal ports. This type of device works to diffuse and scatter light rays uniformly to many different points and directions thereby minimizing the effects of the original light.
Short History Of The Integrating Spheres
integrating sphere
The origin of integrating sphere dates back to 1900. The first and the original details about it were published by R. Ulbricht in the same year. The term Ulbricht sphere is named after him. After the publication, it began to be used as radiometry and photometry instrument. As compared with goniophotometer, Ulbricht sphere became known to function much better as it can measure all light sources using its full power in just a single measurement.
Base Theory
There are two assumptions in which the theory behind which the integrating sphere is based. One is that light is scattered and diffused when hitting the side of the sphere. The other is that the only light which hits the detector and port, are the one which is diffused within the sphere. With this assumption, it has become possible to calculate the multiplier of the sphere.
Uses Of An Integrating Sphere
The integrating sphere is used in optical radiometric and photometric measurements. What it measures is the rest of the light emitted in all directions and points that is coming from a lamp. It is also used to measure the reflection that is diffused into different surfaces showing all angles and illuminations. Because it can collect the light from the port, its detector works to measure the total light incident accurately. As a result, it can also measure the total power of a laser beam without any beam shape effect or polarization.
Materials Used
The lining of the integrating sphere can affect the accuracy of its optical component. Therefore, the ultraviolet and infrared wavelengths must be visible with the use of different coatings. Such coatings may be damaged by the heat coming from high-powered illuminations. To address such an issue, coating materials that fit such a condition is used accordingly.
Barium sulfate and magnesium oxide is used to enhance the visibility of the spectrum light, and they are useful in producing flat reflection. For measuring light, PTFE compounds are also used. Meanwhile, a material that is commonly used to measure infrared light is a gold deposit.
Since coating materials are important to prevent heat damages, the most important requirement in choosing which material is the absence of fluorescence.
Design and Structure
Integrating sphere is designed according to function levels. Small spheres are commonly used for diffusing incoming radiation while bigger ones are used to measure luminaries. They all vary in sizes.
Conclusion
Integrating sphere has basic uses and purposes. Nonetheless, every manufacturer provides certain different features and functions. It is best to check the product specifications to compare.
