# Algorithms used for Microspectroscopy

** Transmittance ** Transmittance calculates a transmission spectrum from a sample and reference single-beam spectra.

* From Two Single-Beam Spectra* Transmission can produce a transmission spectrum from two single-beam spectra using the following formula:

where R is the single beam spectrum of the reference material, S is the single beam spectrum of the sample and D is the dark counts of the system.

* From Absorbance Data*:

A transmission spectrum can be generated from an absorbance spectrum using the following formula:

where A is the absorbance value. This is a calculation from data that has already been collected.

** Absorbance ** Absorbance calculates an absorbance spectrum from a sample and reference single-beam spectra or from a transmission spectrum.

* From Two Single-Beam Spectra*:

Absorbance can produce an absorbance spectrum from two single-beam spectra using the following formula:

where R is the single beam spectrum of the reference material, S is the single beam spectrum of the sample and D is the dark counts of the system.

* From Transmission Data:*

Absorbance can also generate an absorbance spectrum from a transmission spectrum using the following formula:

where %T is the percent transmittance value. This is a calculation from data that has already been collected.

** Reflectance**

Reflectance calculates a reflectance spectrum from a sample and reference single-beam spectra or from an log 1/R spectrum.

* From Two Single-Beam Spectra*:

Reflectance can produce a reflectance spectrum from two single-beam spectra using the following formula:

where R is the single beam spectrum of the reference material, S is the single beam spectrum of the sample and D is the dark counts of the system.