Surgery – Truss – Pad
Patent
1995-05-15
1997-12-09
Bahr, Jennifer
Surgery
Truss
Pad
356136, A61B 500, G01N 2141
Patent
active
056949308
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a device for a qualitative and quantitative in-vitro or in-vivo analysis of a sample by means of attenuated total reflectance utilizing at least one radiation source, an ATR element as well as a detector unit.
STATE OF THE ART
Known is an analysis process for strongly absorbant materials, so-called "attenuated total reflectance" (ATR), first described in 1961 by Harrick and Fahrenfort. This is a reflection method that utilizes the physical phenomena at the interface of two media of different optical density.
If a beam of light impinges obliquely into a medium having a high refraction index n.sub.2 onto an interface to an optically less dense medium having n.sub.1, the beam is reflected back if the angle of incidence .alpha. (the angle between the incident beam of light and the perpendicular on the interface) exceeds the critical angle of total reflectance. A part of the electromagnetic energy, however, nonetheless penetrates to a depth of a few light wavelengths into the optically less dense medium (surface waves).
If the energy of this part returns completely into the medium having a higher refraction index, this is referred to as total reflectance. If, however, the electro-magnetic radiation penetrating into the optically less dense medium is absorbed, the corresponding wavelengths, respectively portions of energy are missing in the reflected ray.
ATR technology is based on this principle. It requires a special optical device which usually is placed in the sample area of a spectrometer. The ATR additional element is composed of a system of mirrors which directs the incident beam into a crystal usually in the form of a trapezoidally cut prism of high reflection factor (e.g. KRS5, Ge, AgCl, or the like), which is in contact with the to-be-examined surface of the sample. In Fahrenfort's original arrangement, total reflectance occurs once at the interface between the crystal and the sample. Presently flat crystal plates to which the sample is pressed from both sides are usually employed. The radiation enters through the bevelled narrow end of the crystal, is reflected back and forth between the surfaces (up to 50 times) and leaves the same through the other narrow crystal end. This type of ATR is also referred to as "multiple reflectance unit", the method as FMIR (frustrated multiple internal reflection) or just MIR.
The previously mentioned physical principles yield the conditions and possibilities of ATR technology. The following points are criteria for the realization of an ATR spectrum: of the sample at a selected wavelength.
Quantative measurements with ATR technology have hitherto not generally been possible, because the contact between the sample and the reflection element is dependent on the pressing force, respectively on the state of the surface of the sample.
DESCRIPTION OF THE INVENTION
The object of the present invention, therefore, is to provide a device for the analysis of the composition of a sample with which both high precision qualitative and quantitative analysis can be carried out not only in vitro but also in vivo. Primarily analysis/measurement precision should be improved compared to the known devices as well as detection ability, which is an important criterium for assessment of the quality of an analysis process. Furthermore, the object of the present invention is to develop a measuring head in miniaturized form which is orders of magnitudes smaller than conventional ATR additional elements.
An invented miniaturized measuring head opens totally new application possibilities extending far beyond those of the present state of the art.
The present invention is based, i.a. on the surprising revelation that this goal can be achieved by, e.g., using an ATR element of a most simple geometric shape, noteably, semi-cylindrical or hemispherical. Therefore, contrary to the state of the art, no complicatedly shaped crystals, which are usually not only expensive but also very sensitive sometimes even poisonous (KRS5|), are not required, but
REFERENCES:
patent: 4169676 (1979-10-01), Kaiser
patent: 4422714 (1983-12-01), Benoit et al.
patent: 4692024 (1987-09-01), Bloss
patent: 4704029 (1987-11-01), Van Heuvelen
Pries Ralf H.
Yoon Dae-Jin
Bahr Jennifer
Kim Yoon-Ok
Winakur Eric F.
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