Principle of operation

Spectroscopy is the study of the absorbance and emission of electromagnetic radiation (light) by matter.

The collection of frequencies absorbed by a sample is its absorption spectrum

When light passes through or is reflected from a sample, the amount of light absorbed is the difference between the:

Incident radiation, I_o, and the transmitted radiation, I. The amount of light that is absorbed is expressed either as transmittance or absorbance.

All spectrophotometers consist of four major sub-units:

a source that generates electromagnetic radiation
a dispersion device that selects a particular wavelength from the broad band radiation of the source
a sample area
a detector to measure the intensity of radiation

Diode array:

Diode arrays are assemblies of individual photodiodes in a linear array.

Self-scanned arrays have the read-out electronics included on the chip with the array.

When read out, all elements of the array must be read out in series. The array has 1024 elements.

Light of all wavelengths falls on the diode-array and is measured simultaneously, that is, data acquisition is done in parallel.

speed is the best known advantage of diode-array spectroscopy.

Data is acquired in parallel, the detectors are read-out by "electronic scanning", and microprocessors and computers are used to process data;

Measurements are made at different wavelengths at the same time. Conventional spectrophotometers can make multi-wavelength measurements but there is a time differential between each measurement.

Home Search Products Applications Press release Application Form Publications Information Request