Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrometer
Reexamination Certificate
1993-07-22
2001-03-20
Hantis, K. P. (Department: 2876)
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrometer
Reexamination Certificate
active
06204919
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to optical instruments which provide analysis of materials, especially for chemical testing, such as blood analysis by means of spectrometry and, more particularly, to a dual beam spectrometer, without any moving parts, which enables simultaneous display and analysis of sample and reference beams with adjustments made for attenuation losses in the sample beam and for fluctuations in either beam.
The invention may be used in any spectropic system which performs chromatography. The preferred embodiment is used for high pressure liquid chromatography (HPLC). The improvements in spectrometry provided by the invention will be useful in other spectrometric instruments.
BACKGROUND OF THE INVENTION
Basically, a spectrometer is an optical device which uses a prism, diffraction grating or interferometer to separate light into its constituent parts. With a spectrometer, scientists and others are able to study matter by analyzing the spectrum produced by light passed through the matter. This has provided scientists and others with a powerful analytic tool. Unfortunately, limitations with spectrometers themselves have hindered the use of spectroscopy.
For example, many spectrometers utilize mechanically moving parts to control the transmission of light. These parts are subject to failure from repeated use and have inherent speed limitations. Additionally, spectrometers have traditionally lacked the ability to simultaneously display and analyze sample and reference beams. As a result, errors are often introduced by the sequential display and analysis. Even further, heretofore spectrometer have not effectively compensated for attenuation losses during display and analysis and have required complicated electronics and software to separate the desired signals from the noise in the detection systems.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide an improved spectrometer.
It is another object of the present invention to provide a spectrometer which compensates for attenuation losses.
It is a further object of the present invention to provide a spectrometer which improves signal to noise ratios enabling less expensive control electronics and software to be utilized.
According to the present invention, these and other objects and advantages are achieved in a dual beam spectrometer, without any moving parts, which includes a light source, a fiber optic bundle which splits into a first and second leg, with the first leg having more fibers than the second leg, a transmission cell positioned at the end of the first leg, focusing optics positioned at the end of the second leg and on the opposing side of the transmission cell, a dispersing device for separating the sample and reference beams into their constituent parts, and a detector for detecting the constituent parts.
The elimination of mechanical moving parts and the simultaneous display and analysis of sample and reference beams allows for high speed and repeated analysis suitable for commercial industries. Attenuation losses in the sample beams are compensated for with the differentiation in the number of fibers in the first and second legs. Further compensation for attenuation losses can be obtained by making the overall length of the second leg longer than the first leg and by tapering the transmission cell. The addition of mask filters between the dispersing device and the detector compensates for wavelength dependent source intensities, thereby improving the signal to noise ratio and allowing for the use of less sophisticated and expensive electronic control circuitry and software for processing and analyzing the data.
The spectrometer may be housed in a casing made from low thermal expansion material. The housing helps to minimize long-term drift caused by changes in ambient temperature.
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Barshad Yael
Barshad Yoav
Hantis K. P.
Harris Beach & Wilcox, LLP.
NovaChem BV
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