An optical aberration is a departure of the performance of an optical system from the predictions of parallel axis optics. In a spectrometer, an optical aberration is typically seen when light from a single point does not converge back into a point after passing through the system and is seen as a “blur” or “smear” in the spectrum. Aberrations are [..]

Absolute irradiance calibrations require a lamp of known spectral power output to calibrate the spectrometer’s response at each pixel. This modifies the shape and magnitude of the whole spectrum, correcting for the instrument’s individual instrument response function. The modified spectrum is given in terms of power per area per wavelength, commonl [..]

Absorbance is measured in the dimensionless unit, AU. To understand how this relates to transmission, we must consider the Beer-Lambert (or Beer’s) Law:

The analog input/output pins allow the spectrometer to communicate with an external device. For example, the voltage on the output pin can be incrementally varied within a specified range to control an external device, so a lamp controlled by the analog output pin may change intensity based on the voltage produced by the spectrometer. In this situa [..]

This component in the spectrometer is responsible for converting the voltage from the detector into a digital signal that is sent to and processed by the computer for graphical display. The incident photons produce electrons in the detector pixels, which are then converted by the A/D into a digital signal. The speed at which the A/D sends data to t [..]

The autonulling feature available on certain spectrometers is designed to adjust the baseline offset of the spectrometer to a user defined level. This is useful when trying to use two different spectrometers to look at the same light source. Using autonulling, the baselines of the different spectrometers can be made to match each other.

When viewing or capturing a spectrum, two kinds of signal averaging are possible: time-based averaging and spatially based averaging.

Background is the signal level that represents the expected output when no sample is present. This is distinct from a dark or dark spectrum, which represents the expected output when absolutely no light is present. This important distinction can be seen in the following example:

See Defective Pixel

In semiconductors, such as silicon detectors, the bandgap refers to the electron energy difference between the top of the valence band and the bottom of the conduction band. When a photon with energy that matches this bandgap lands on the detector, an electron is promoted from the valence to the conduction band and is added to the pixel “pool” for [..]