Self referencing LED detection system for spectroscopy applications

Abstract

A light emitting diode (LED) based detection system is employed for spectroscopy based applications. LEDs are used as monochromatic light sources for applications at specific and pre-defined wavelengths. Spectrographic information is generated using LEDs of different wavelengths ranging from 260 nm to 1400 nm. Multiple wavelength information is generated by coupling light from each LED into an intensity and mode mixing fiber bundle. A dual beam approach of using a reference and a sample photodiode ensures automatic drift correction. Interference filters at the LED input fiber reduce the spectral bandwidth of the monochromatic light emission to a useful 10 nm bandwidth by cutting off the LEDs trailing emission distribution allowing for absorbance measurements similar to typical spectrometers.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the priority of U.S. Provisional Application No. 60 / 885,588 filed Jan. 20, 2007.BACKGROUND[0002]Absorption spectroscopy uses the range of electromagnetic spectra in which a substance absorbs. In absorption spectroscopy light of a particular wavelength is passed through the sample. After calibration, the amount of absorption can be related to the sample concentration through the Beer-Lambert law. Examples of absorption spectroscopy include, for example, ultraviolet / visible (UVNIS) absorption spectroscopy (most often performed on liquid samples to detect molecular content) and infrared (IR) spectroscopy (most often performed on liquid, semi-liquid (paste or grease), dried, or solid samples to determine molecular information, including structural information).[0003]Spectroscopic analysis typically uses a spectrometer. The spectrometer typically includes a radiation source such as a deuterium, tungsten or xenon lamp cap...

AI Technical Summary

Benefits of technology

"The patent describes a detection system that uses multiple wavelengths of LEDs for spectroscopy applications. The system is designed to measure small samples and can be used for fluorescence applications. The LEDs are stable and can be driven in constant current mode. The system uses a large mixing fiber to combine the light from the LEDs, which is then detected by a reference photodiode and a sample photodiode. The system automatically corrects for any drift or stray light, ensuring accurate measurements and long-term stability. The system also uses interference filters to optimize light throughput. The technical effects of this patent are a more precise and accurate detection system for spectroscopy applications."

Problems solved by technology

While this equipment provides analysis flexibility, it also requires complicated and expensive light sources, gratings, monochromators and other components to take advantage of this flexibility.

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