What is a Cosine Receptor?

Nov 10, 2017 | Glossary of Spectroscopy Terms, Sampling

A cosine receptor (sometimes called a cosine corrector) is a type of light receptor that is used for radiometry and photometry. It collects all light in a 180 degree field of view, making it suitable for measuring light from a planar surface or light from multiple...

What is Photosynthetically Active Radiation (PAR)?

Nov 10, 2017 | Characterization, Glossary of Spectroscopy Terms

Photosynthetically active radiation is any radiation that can be used for photosynthesis. This is generally wavelengths in the visible range (400-700nm). Radiation outside this range is given zero weight. This is slightly different than photometry, which has...

What is Photosynthetic Photon Flux Density?

Nov 10, 2017 | Characterization, Glossary of Spectroscopy Terms

The photosynthetic photon flux density is the amount of photosynthetically active photons (400-700nm) hitting a surface per unit area per unit time. The units are µmol (of photons) m-2 s-1.

What is Radiometry?

Nov 10, 2017 | Characterization, Glossary of Spectroscopy Terms

Radiometry is simply the measurement of light. There are many characteristics of light that can be measured, but the most common are wavelength (color) related quantities and power related quantities, such as irradiance. StellarNet offers spectroradiometer systems for...

What is Color Rendering Index (CRI)?

Nov 10, 2017 | Glossary of Spectroscopy Terms, Properties of Light

The color rendering index is a way to quantify whether colors under a light source will look the same as in daylight. This is reflected (figuratively and literally) in the light source’s spectrum. A light source with a spectrum that is different than the sun will have...