The most common optical measurements in UV/VIS/NIR spectrum are absorbance, transmittance and reflectance. Transmittance (T) is the fraction of incident light which is transmitted through the sample. On the other hand, absorbance (A) describes how much of incident light is absorbed in the sample. Absorbance is calculated through transmittance measurements by applying the following formula:


By employing absorbance and transmittance measurements, we can measure how much radiant energy a substance absorbs at the individual wavelengths. Absorbance and transmittance measurements are usually applied in liquids but also in the characterization of coatings deposited on transparent substrates (e.g. glasses or quartz).

In particular by using absorbance and transmittance measurements the identity of unknown substance is determined. Furthermore, by employing a set of standards, a substance concentration in sample can be determined through absorbance measurements at certain for the substance wavelengths.

FR-pRo tool when accompanied with FR-Transmittance kit, supports accurate transmittance and absorbance measurements for liquids and films deposited on transparent substrates as well. FR-transmittance kit is secured on the benchtop of FR-pRo and accommodates standard 10mm cuvettes and solid samples of 5mm thickness maximum. The transmittance & absorbance measurements are performed through the standard FR-Monitor in the spectral range supported by FR-pRo.



Typical Application Notes:

App011- Absorption measurements
App012- Absorption measurements
App016- Sensitivity of Photoresist films
App017- Colour filters
App032- Relative transmission haze measurements of a polymer on glass substrate

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