Integrating Spheres: Their Application in Reflectance Spectroscopy

Reflectance spectroscopy is a versatile analytical technique which can reveal a material’s chemical composition, as well as allowing colour to be quantified in a multitude of applications in biology, pharmaceuticals, art and cultural heritage, consumer products and many more.

Reflectance measurements can be made in a variety of ways, but the preferred approach is to use an integrating sphere in combination with a light source and a spectrometer. With the sample surface illuminated, the integrating sphere captures all of the reflected light over a complete hemisphere, which is then sampled by a spectrometer coupled to the sphere. The spectral reflectance recorded allows the object’s colour to be computed, while the spectral signature will be characteristic of the chemical formulation which provides an insight into the makeup of the material.

In this white paper, Pro-Lite’s Robert Yeo will review the science of integrating spheres and diffuse reflectance, explain how they are used in reflectance spectroscopy, define the various sources of error and how they can be mitigated, and compare the use of integrating spheres to other approaches to measuring reflectance.