http://rdf.ncbi.nlm.nih.gov/pubchem/patent/GB-1168815-A
Outgoing Links
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|---|---|
| assignee | http://rdf.ncbi.nlm.nih.gov/pubchem/patentassignee/MD5_bbd4b6f3962247ae46ee78cfe5d25777 |
| classificationCPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/G01J3-10 http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/G01N21-27 http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/G01N21-255 http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/G01J3-42 |
| classificationIPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/H04B10-152 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G01N21-07 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G02B6-42 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G02B6-38 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G02B6-36 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G01N21-27 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G01N21-25 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G01N21-33 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G01J1-16 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/H03B17-00 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G01J3-42 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/B04B11-02 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G02B6-40 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G01V5-02 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/A61B10-02 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/B01L3-14 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/A61B10-00 http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/G01N21-85 |
| filingDate | 1966-11-10-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| publicationDate | 1969-10-29-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| publicationNumber | GB-1168815-A |
| titleOfInvention | Apparatus for Measuring Absorbance Differences |
| abstract | 1,168,815. Photo-electric absorption measurement. INSTRUMENTATION SPECIALITIES CO. Nov. 10, 1966 [Aug.2, 1966], No.50425/66. Heading G1A. Photo-electric apparatus for measuring the difference in absorbance (absorption co-efficient) between liquids contained in two test chambers 12, 12<SP>1</SP> comprises a pair of photo-electric detectors 13, 13<SP>1</SP> receiving light from a source 10, 11 transmitted through the test chambers, the detectors being connected in series and in such a way that the apparatus responds substantially logarithmically to the detected light intensities. Direct measurement of the absorbance difference is therefore possible since absorbance is logarithmically related to the transmitted light-intensity through a chamber. The measuring voltmeter is biased to operate in the linear part of the curve of voltage response against absorbance, Fig. 3 (not shown). If the photo-resistive type of detectors used, whose conductivity varies as the square root of the incident light-intensity, the detectors 13, 13<SP>1</SP> are connected in a bridge circuit in association with fixed resistors 17, 18, Fig. 1, so that the circuit responds logarithmically. The voltage across the bridge then gives an indication of the difference in absorption co-efficient detected between the two test chambers, one of which may act as a reference. In a modified circuit, Fig.4 (not shown), the voltmeter is connected across one of the detectors (13<SP>1</SP>) and the fixed resistors are omitted, the photo-resistors (13) modifying the response of the other (13<SP>1</SP>) to a logarithmic one. Semiconductor detectors, of the p-n junction type, may be used, Fig. 5 (not shown), being connected in opposition and responding logarithmically without the need for associated fixed series resistors. However, temperature compensation, unnecessary with the Fig. 1 circuit, is then required. The optical apparatus includes a source comprising a mercury vapour lamp 10 exciting a cerium-activated lanthanium fluoride phosphor coated on a transparent tube 11. Either ultraviolet light from the tube 11 at 280 mÁ or from the lamp 10 at 254 mÁ is directed to test chambers 12, 12<SP>1</SP>. Movable slide members 28, 28<SP>1</SP> with apertures 32, 32<SP>1</SP> and mirrors 33, 33<SP>1</SP>, 34, 34<SP>1</SP> provide for this choice. Movable slide members 36, 40 one having an aperture 37 and the other carrying absorption standards, are provided to enable calibration of the apparatus. Fluorescent filters 14, 14<SP>1</SP> are associated with the detectors 13, 13<SP>1</SP> to convert ultraviolet radiation, within the bandwidth of 245-290 mÁ into visible light to which the detectors can respond. Source construction In Figs.8, 9 (not shown), an elliptical cylinder reflector is used to focus light from the lamp 10 into the tube 11. A tungsten or hydrogen discharge lamp associated with suitable mono-chromator and filters may be used instead of a mercury lamp. |
| isCitedBy | http://rdf.ncbi.nlm.nih.gov/pubchem/patent/EP-0228877-A2 http://rdf.ncbi.nlm.nih.gov/pubchem/patent/EP-0228877-A3 |
| priorityDate | 1966-08-02-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| type | http://data.epo.org/linked-data/def/patent/Publication |
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