GB2071354A - Sample cell for spectroscopy - Google Patents

Sample cell for spectroscopy Download PDF

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Publication number
GB2071354A
GB2071354A GB8107073A GB8107073A GB2071354A GB 2071354 A GB2071354 A GB 2071354A GB 8107073 A GB8107073 A GB 8107073A GB 8107073 A GB8107073 A GB 8107073A GB 2071354 A GB2071354 A GB 2071354A
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GB
United Kingdom
Prior art keywords
pipe
section
optical
light
sections
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB8107073A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ACCUSPEC Ltd
Original Assignee
ACCUSPEC Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ACCUSPEC Ltd filed Critical ACCUSPEC Ltd
Priority to GB8107073A priority Critical patent/GB2071354A/en
Publication of GB2071354A publication Critical patent/GB2071354A/en
Withdrawn legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03Cuvette constructions
    • G01N21/0303Optical path conditioning in cuvettes, e.g. windows; adapted optical elements or systems; path modifying or adjustment

Abstract

The cell minimizes the volume contained while maximising the light path through it. It is made up of two sections (1, 2) suitably of internally reflecting stainless steel tube, joined at an angle of between 20 DEG and 60 DEG (preferably about 30 DEG ) and having a mirror (8) across the join. An optical window (5) and fluid inlet (3) is at one end of one section (1) remote from the mirror and an optical window (6) and fluid outlet (4) at the remote end of the other section (2). The optical windows (5, 6) may be removable from the pipe. Light injected in one passes down the first section and is reflected by the mirror to pass to the other window. <IMAGE>

Description

SPECIFICATION Light pipe for spectroscopy This invention relates to a light pipe for use in spectroscopy.
According to the invention there is provided a light pipe comprising at least two sections joined end to end, the first section having at its upstream end an optical entrance for light and a nearby inlet port for gas, and the last section having at its downstream end an optical exit and a nearby outlet port for gas, each upstream section extending at an angle to the section immediately downstream of it with a mirror portion at their junction which reflects light passing down the upstream section into the downstream section.
The pipe can be of any cross-section. For compactness a cross-section having a greater height than breadth is preferred, for example rectangular or oval.
It is also possible to have several intermediate sections between the first and second section such that at each joint between two sections there is a mirror which reflects light passing down upstream section into the downstream section.
The gas inlet and outlet ports are close to the optical entrance and exit apertures. These are closed by materials which allow the transmission of the light beam of the desired frequency but do not allow the escape of gas. The pipe can of course also be used for examining gas samples over longer periods in which case the gas is first filled into the pipe and the inlet and outlet ports are then closed.
The advantages of the invention are that due to the angled form the pipe can be made very compact allowing it to be fitted into the standard sample compartment of commercially available spectrometers. The ratio of the optical path length to the internal volume of the pipe can be made very high thereby giving excellent sensitivity for measurements even if there are only small quantities of sample in the pipe.
The gas or other fluid flow through the pipe is such that mixing and vehicle diffusion are minimized and thus the pipe can be used for infrared analysis of chromatography effluents as they flow through the pipe with no appreciable peak broadening.
A pipe can simply be made of stainless steel with the interior of the pipe polished. Alternatively a special reflecting coating can be used.
A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 is a perspective view of a pipe, and Figure 2 is a view from above of the pipe of Figure 1.
The pipe has two sections 1, 2. There is a gas inlet 3 and a gas outlet 4. End 5 is an optical entrance which is suitably at the focus of a spectrometer beam, while end 6 is an optical exit and is positioned at the focus of an optical mirror which allows the light to be collected and transferred through the optical system of the spectrometer (not shown) in a conventional manner.
The cross-section of the pipe is rectangular of size 2 mm. by 10 mm. and the length of each arm of the 'V' is 5 cm. The angle between the arms of the 'V' is 30 though other angles, preferably between 200--600 are possible. The smaller the angle the more compact is the device.
The optical mirror 8 is a plane mirror of such size and dimension that all light passing axially down arm of the 'V' will be transmitted to the other arm along the longitudinal axis of each arm.
This means that light passing down the V sections at other angles will for the most part also be reflected into the next arm. The pipe can consist of more than two angled sections.
The pipe can suitably be made of stainless steel which is polished within the cavity. The gaskets for the gas inlet and outlet can suitably be made of PTFE and the end windows are removably mounted. They can suitably be made of potassium bromide. The working range of such a pipe can extend up to 2700C and 3000C depending on the materials used. Optical transmission of the complete device is about 1 5% T in the infra-red range.
The use of removably mounted end windows which are clamped to the ends allows the pipe to be heated and cooled while it is gas tight without danger of breaking window material. Details of this, and of uses of the sample cavity are described in co-pending Application No. 7352/77 (Serial No. 1576932) the contents of which are hereby incorporated.
1. A light pipe for use in spectroscopy comprising at least two sections joined end to end, the first section having at its upstream end an optical entrance for light and a nearby inlet port for fluid, and the last section having at its downstream end an optical exit and a nearby outlet port for fluid, each upstream section extending at an angle to the section immediately downstream of it with a mirror portion at their junction which reflects light passing down the upstream section into the downstream section.
2. A light pipe according to claim 1 wherein the said optical entrance and optical exit have removably mounted end windows.
3. A light pipe according to claim 1 or claim 2 wherein the said mirror is a plane mirror.
4. A light pipe according to any one of claims 1 to 3 wherein the said sections are made of stainless steel tube the internal surface of which is polished.
5. A light pipe according to any one of the preceding claims wherein the angle between each section and its next adjacent section is between about 200 and 600.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Light pipe for spectroscopy This invention relates to a light pipe for use in spectroscopy. According to the invention there is provided a light pipe comprising at least two sections joined end to end, the first section having at its upstream end an optical entrance for light and a nearby inlet port for gas, and the last section having at its downstream end an optical exit and a nearby outlet port for gas, each upstream section extending at an angle to the section immediately downstream of it with a mirror portion at their junction which reflects light passing down the upstream section into the downstream section. The pipe can be of any cross-section. For compactness a cross-section having a greater height than breadth is preferred, for example rectangular or oval. It is also possible to have several intermediate sections between the first and second section such that at each joint between two sections there is a mirror which reflects light passing down upstream section into the downstream section. The gas inlet and outlet ports are close to the optical entrance and exit apertures. These are closed by materials which allow the transmission of the light beam of the desired frequency but do not allow the escape of gas. The pipe can of course also be used for examining gas samples over longer periods in which case the gas is first filled into the pipe and the inlet and outlet ports are then closed. The advantages of the invention are that due to the angled form the pipe can be made very compact allowing it to be fitted into the standard sample compartment of commercially available spectrometers. The ratio of the optical path length to the internal volume of the pipe can be made very high thereby giving excellent sensitivity for measurements even if there are only small quantities of sample in the pipe. The gas or other fluid flow through the pipe is such that mixing and vehicle diffusion are minimized and thus the pipe can be used for infrared analysis of chromatography effluents as they flow through the pipe with no appreciable peak broadening. A pipe can simply be made of stainless steel with the interior of the pipe polished. Alternatively a special reflecting coating can be used. A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 is a perspective view of a pipe, and Figure 2 is a view from above of the pipe of Figure 1. The pipe has two sections 1, 2. There is a gas inlet 3 and a gas outlet 4. End 5 is an optical entrance which is suitably at the focus of a spectrometer beam, while end 6 is an optical exit and is positioned at the focus of an optical mirror which allows the light to be collected and transferred through the optical system of the spectrometer (not shown) in a conventional manner. The cross-section of the pipe is rectangular of size 2 mm. by 10 mm. and the length of each arm of the 'V' is 5 cm. The angle between the arms of the 'V' is 30 though other angles, preferably between 200--600 are possible. The smaller the angle the more compact is the device. The optical mirror 8 is a plane mirror of such size and dimension that all light passing axially down arm of the 'V' will be transmitted to the other arm along the longitudinal axis of each arm. This means that light passing down the V sections at other angles will for the most part also be reflected into the next arm. The pipe can consist of more than two angled sections. The pipe can suitably be made of stainless steel which is polished within the cavity. The gaskets for the gas inlet and outlet can suitably be made of PTFE and the end windows are removably mounted. They can suitably be made of potassium bromide. The working range of such a pipe can extend up to 2700C and 3000C depending on the materials used. Optical transmission of the complete device is about 1 5% T in the infra-red range. The use of removably mounted end windows which are clamped to the ends allows the pipe to be heated and cooled while it is gas tight without danger of breaking window material. Details of this, and of uses of the sample cavity are described in co-pending Application No. 7352/77 (Serial No. 1576932) the contents of which are hereby incorporated. CLAIMS
1. A light pipe for use in spectroscopy comprising at least two sections joined end to end, the first section having at its upstream end an optical entrance for light and a nearby inlet port for fluid, and the last section having at its downstream end an optical exit and a nearby outlet port for fluid, each upstream section extending at an angle to the section immediately downstream of it with a mirror portion at their junction which reflects light passing down the upstream section into the downstream section.
2. A light pipe according to claim 1 wherein the said optical entrance and optical exit have removably mounted end windows.
3. A light pipe according to claim 1 or claim 2 wherein the said mirror is a plane mirror.
4. A light pipe according to any one of claims 1 to 3 wherein the said sections are made of stainless steel tube the internal surface of which is polished.
5. A light pipe according to any one of the preceding claims wherein the angle between each section and its next adjacent section is between about 200 and 600.
6. A light pipe according to any one of the preceding claims wherein the cross-sections of the said at least two sections is rectangular and is about 2 mm. by 10 mm.
7. A light pipe substantially as herein described with reference to the accompanying drawings.
GB8107073A 1980-03-10 1981-03-06 Sample cell for spectroscopy Withdrawn GB2071354A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8107073A GB2071354A (en) 1980-03-10 1981-03-06 Sample cell for spectroscopy

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8008051 1980-03-10
GB8107073A GB2071354A (en) 1980-03-10 1981-03-06 Sample cell for spectroscopy

Publications (1)

Publication Number Publication Date
GB2071354A true GB2071354A (en) 1981-09-16

Family

ID=26274751

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8107073A Withdrawn GB2071354A (en) 1980-03-10 1981-03-06 Sample cell for spectroscopy

Country Status (1)

Country Link
GB (1) GB2071354A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998038487A3 (en) * 1997-02-28 1998-11-19 Cepheid Heat exchanging, optically interrogated chemical reaction assembly

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998038487A3 (en) * 1997-02-28 1998-11-19 Cepheid Heat exchanging, optically interrogated chemical reaction assembly

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Legal Events

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)