Optics: measuring and testing – For light transmission or absorption – Of fluent material
Patent
1996-07-29
1998-08-18
Nelms, David C.
Optics: measuring and testing
For light transmission or absorption
Of fluent material
G01N 2100
Patent
active
057964890
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a hollow vacuum-tight shaped body made of ceramic material for measuring transmission and absorption of electromagnetic radiation in liquids and gases, for completing spectrometers for transmission and absorption measurement under highly aggressive conditions; it may be used in a plurality of variants in optical measurement technology (spectrometry) as an optical waveguide adapter assembly.
BACKGROUND OF THE INVENTION
There are required, for measurement analysis technology, sensors with optical measuring principles which enable investigation of liquid and gaseous media even under chemically aggressive conditions and if necessary at high temperatures. On the basis of light-optical measuring principles, spectra for transmission and absorption are absorbed by means of light of variable wavelength. More recent apparatus operates on the basis of optical waveguides.
Both submerging cells (fork-) and continuous-flow (tubular) cells made of glass are used as measuring probes. In order to carry out spectroscopy even at wavelengths in the range of 200-300 nm, submerging cells of quartz glass are used. The round or oval fork arms, in which the optical system is protected from the medium being investigated, are produced by glass-blowing. The disadvantage is the inaccuracy of the medium coating thickness due to the manufacturing process.
More accurate structures of quartz glass are manufactured as prismatic fork arrangements by soldering or wringing/diffusion welding (Company title: Carl Zeiss Oberkochen, Submerging probe TS 5). This construction is considerably more accurate. It has however the drawback that the joining zones, with glass solder, are not very chemically resistant. In the case of diffusion-welded cells, the chemical resistance of quartz glass is essential for the range of possible operational conditions; this however is less than that of ceramics. No other glass material is known for the short-wave spectroscopy range.
SUMMARY OF THE INVENTION
The object of the invention is to provide a hollow vacuum-tight ceramic shaped body which may be of complex geometric structure, and which has openings which are closed in a thermally and chemically resistant manner by material which is permeable to electromagnetic radiation, with a highly precise medium coating thickness of the closure medium.
This object is achieved according to the invention by a hollow vacuum-tight shaped body made of ceramic material for measuring transmission and absorption of electromagnetic radiation in liquids and gases, in that the ceramic material consists principally of Al.sub.2 O.sub.3 ceramics, and has one or a plurality of apertures of any size which are integrally and permanently closed by optical windows of material which is permeable to electromagnetic radiation in the wavelength range from 180 nm to 5.5 .mu.m. Before the sintering process, a green sintering ceramic film is arranged between the aperture and the material which is permeable to electromagnetic radiation in the wavelength range from 180 nm to 5.5 .mu.m, the joining being brought about by a sintering process at a surface pressure of from 0.2 to 4 MPa such that it is integral, permanent and vacuum-tight. If the shaped body has a complex structure, it can comprise at least two ceramic shaped body parts, a green sintering ceramic film, structured according to the shape of the surfaces to be connected, likewise being disposed therebetween. Further embodiment of the invention may be seen in the sub-claims.
The advantage of the invention resides in the fact that the hollow vacuum-tight shaped body consists principally of Al.sub.2 O.sub.3 ceramics, its apertures being closed by optical windows of a material which is permeable to electromagnetic radiation of from 180 nm to 5.5 .mu.m, particularly sapphire, and whose medium coating thickness is of high precision, with excellent chemical and thermal resistance, and in that, for example when the shaped body is of complex structure, it may be assembled from a plurality of shaped body parts by means o
REFERENCES:
patent: 5044755 (1991-09-01), Landa et al.
patent: 5046854 (1991-09-01), Weller et al.
Emmrich Roland
Krippl Gerhardt
Merlino Amanda
Nelms David C.
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