GB2537870A - Light detecting apparatus - Google Patents
Light detecting apparatus Download PDFInfo
- Publication number
- GB2537870A GB2537870A GB1507296.0A GB201507296A GB2537870A GB 2537870 A GB2537870 A GB 2537870A GB 201507296 A GB201507296 A GB 201507296A GB 2537870 A GB2537870 A GB 2537870A
- Authority
- GB
- United Kingdom
- Prior art keywords
- type
- polarised light
- light
- converting
- elliptically
- 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- Withdrawn
Links
- 230000005284 excitation Effects 0.000 claims abstract description 14
- 230000001419 dependent effect Effects 0.000 claims abstract description 12
- 229910052724 xenon Inorganic materials 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 9
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 5
- 150000003736 xenon Chemical class 0.000 abstract description 2
- 238000001228 spectrum Methods 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 3
- HBAQYPYDRFILMT-UHFFFAOYSA-N 8-[3-(1-cyclopropylpyrazol-4-yl)-1H-pyrazolo[4,3-d]pyrimidin-5-yl]-3-methyl-3,8-diazabicyclo[3.2.1]octan-2-one Chemical class C1(CC1)N1N=CC(=C1)C1=NNC2=C1N=C(N=C2)N1C2C(N(CC1CC2)C)=O HBAQYPYDRFILMT-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000004611 spectroscopical analysis Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000000978 circular dichroism spectroscopy Methods 0.000 description 1
- 238000000295 emission spectrum Methods 0.000 description 1
- 238000004020 luminiscence type Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
- G01J3/0224—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows using polarising or depolarising elements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J3/443—Emission spectrometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J3/447—Polarisation spectrometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J4/00—Measuring polarisation of light
- G01J4/04—Polarimeters using electric detection means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/19—Dichroism
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/21—Polarisation-affecting properties
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/64—Fluorescence; Phosphorescence
- G01N21/6445—Measuring fluorescence polarisation
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
Abstract
A light detecting apparatus 1 has first converting means for converting elliptically polarized light of a first type 6 emitted by an object 2 to linearly polarized light of a first type 10, and second converting means for converting elliptically polarized light of a second type 8 emitted by the object 2 to linearly polarized light of a second type 12. A first 16 and second 18 detector provide an output signal 26, 28 dependent on an intensity of the linearly polarized light of the first type 10 and second type 12 respectively. The first and/or second converting means may comprise at least one waveplate 4. Separating means such as a polarizing beam splitter 14 may separate the linearly polarized light of said first type 10 and second type 12. The apparatus may be used to analyze a sample containing chiral material e.g. to monitor the enantiometric content of the sample. The apparatus may detect left- and right-handed elliptically or circularly polarized light. The sample may be illuminated by excitation means in the form of a xenon bulb 30 energized by a pulsed pump laser 32.
Description
LIGHT DETECTING APPARATUS
The present invention relates to a light detecting apparatus and relates particularly, but not exclusively, to a light detecting apparatus for simultaneously detecting left-and right-handed circularly polarised light.
Two molecules are said to exhibit chirality if they are non-superposable mirror images of each other while being otherwise identical. When two molecules exhibit chirality, they are called enantiomers and can be respectively designated left-handed and right-handed.
Enantiomers respond differently when interacting with other chiral systems. For example, each enantiomer will absorb a different amount of incident circularly polarised (CP) light. Circular dichroism spectroscopy is a branch of spectroscopy concerned with measuring this differential absorption phenomenon and using it to investigate the enantiomeric content of a sample, which can change with time.
One approach to analysing a sample containing chiral material involves optically exciting the sample and monitoring the consequent spectrum of CP light emitted. The spectrum of CP light emitted by the sample contains information directly related to the enantiomeric content of that sample on the basis that a left-handed enantiomer emits a different spectrum of light to its right-handed counterpart. This forms the basis of circularly polarised luminescence (CPL) spectroscopy.
An existing method for monitoring the enantiomeric content of a sample includes the use of a photoelastic modulator (PEM) wherein a piece of material, such as silica, is used as an optical element driven at resonance by an alternating voltage across a piezoelectric transducer attached to the material. As a consequence of this mechanical excitation, the material's birefringence oscillates with a frequency proportional to the mechanical resonance frequency of the optical element. The PEM then acts in a similar way to a wave plate, converting elliptically polarised light emitted by the sample into linearly polarised light. Using a PEM in a spectroscopic apparatus necessitates the use of a lock-in amplifier (LIA) to adjust the magnitude of birefringence of the PEM to appropriately convert the emitted elliptically polarised light to linearly polarised light.
A PEM is an optical element that functions as a quarter wave plate and oscillates between states of left hand and right hand polarisation of the incident light. This is subsequently converted into linearly polarised light (parallel and perpendicular) before detection.
A PEM therefore has a characteristic sampling rate limited by that frequency, which subsequently limits the rate at which data can be acquired. In addition, spectroscopic apparatus utilising a PEM cannot monitor the LCP and RCP emission spectra simultaneously and therefore cannot independently monitor how the amounts of each enantiomer present in a sample change with time. Furthermore, the use of a PEM requires use of a LIA to modulate the mechanical excitation of the PEM, which increases the size and cost of the apparatus.
Preferred embodiments of the present invention seek to overcome one or more of the above disadvantages associated with the prior art.
According to a first aspect of the present invention, there is provided a light detecting apparatus comprising: first converting means for converting elliptically polarised light of a first type emitted by an object to linearly polarised light of a first type; second converting means for converting elliptically polarised light of a second type emitted by said object to linearly polarised light of a second type; first detector means for providing an output signal dependent on an intensity of said linearly polarised light of said first type; and second detector means for providing an output signal dependent on an intensity of said linearly polarised light of said second type.
By providing first converting means for converting elliptically polarised light of a first type emitted by an object to linearly polarised light of a first type, second converting means for converting elliptically polarised light of a second type emitted by said object to linearly polarised light of a second type, first detector means for providing an output signal dependent on an intensity of said linearly polarised light of said first type, and second detector means for providing an output signal dependent on an intensity of said linearly polarised light of said second type, this provides the advantage of measuring both the elliptically polarised light of said first type and the elliptically polarised light of said second type independently, thereby enabling simultaneous detection of said first and second types of elliptically polarised light. Furthermore, this provides the advantage of reducing the size and cost of the apparatus.
Said first converting means and/or said second converting means may comprise at least one wave plate.
The apparatus may further comprise separating means for separating said linearly polarised light of said first type from said linearly polarised light of said second type.
The separating means may comprise at least one polarising beam splitter.
The apparatus may further comprise excitation means for causing said object to emit elliptically polarised light of said first and second types.
The excitation means may comprise at least one light-emitting diode (LED).
The excitation means may comprise at least one laser and at least one bulb containing xenon.
The excitation means may be adapted to be pulsed.
According to a second aspect of the present invention, there is provided a light detecting method, comprising: converting elliptically polarised light of a first type emitted by an object into linearly polarised light of a first type; converting elliptically polarised light of a second type emitted by said object into linearly polarised light of a second type; providing an output signal dependent on an intensity of said linearly polarised light of said first type; and providing an output signal dependent on an intensity of said linearly polarised light of said second type.
The method may further comprise separating said linearly polarised light of said first type from said linearly polarised light of said second type.
The method may further comprise causing said object to emit said elliptically polarised light of said first and second types.
The method may further comprise pulsing excitation means for causing said object to emit said elliptically polarised light of said first and second types.
A preferred embodiment of the present invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which: Figure 1 shows a schematic view of a light detecting apparatus embodying the present invention; and Figure 2 shows two circular polarisation spectra as recorded by the apparatus of Figure 1.
Referring to Figure 1, a light detecting apparatus 1 embodying the present invention is shown wherein light emitted by an object in the form of a sample 2 is incident on a converting means in the form of a wave plate 4. This emitted light comprises a mixture of left-handed elliptically polarised light 6 and right-handed elliptically polarised light 8 in an unknown proportion. The characteristics of the wave plate 4 are chosen such that the elliptically polarised components 6, 8 of the light emitted by the sample 2 are converted into a first linearly polarised component 10 and a second linearly polarised component 12, polarised in a plane orthogonal to that of the first component 10 as a result of passing through the wave plate 4. These linearly polarised components 10, 12 are incident on a polarising beamsplitter 14, which separates the first component 10 from the second component 12. The first component 10 is detected by first detecting means 16 such as a photomultiplier and/or photodiode, while the second component 12 is detected by second detecting means 18. The first 16 and second detecting means 18 are shown connected to a processor such as a PC 20 for recording and analysis of input data. The sample 2 is illuminated by light emitted by excitation means in the form of a xenon bulb 30 energised by a pulsed pump laser 32 having passed through a monochromator 34.
Referring to Figure 2, data dependent on the outputs of both first 16 and second detecting means 18 are shown on a graph displaying the intensity of each of the elliptically polarised components 6, 8 as a function of wavelength. This graph shows a significant difference between the intensity of the left-handed component 6 and the right-handed component 8 at an approximate wavelength of 610nm, demonstrating a difference in enantiomeric content of the sample 2 proportional to that difference.
It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims.
Claims (12)
- Claims 1.A light detecting apparatus comprising: first converting means (4) for converting elliptically polarised light of a first type (6) emitted by an object (2) to linearly polarised light of a first type (10); second converting means (4) for converting elliptically polarised light of a second type (8) emitted by said object (2) to linearly polarised light of a second type (12); first detector means (16) for providing an output signal (26) dependent on an intensity of said linearly polarised light of said first type (10); and second detector means (18) for providing an output signal (28) dependent on an intensity of said linearly polarised light of said second type (12).
- 2. An apparatus according to claim 1, wherein said first converting means and/or said second converting means comprises at least one wave plate (4).
- 3.An apparatus according to claim 1 or 2, further comprising separating means (14) for separating said linearly polarised light of said first type (10) from said linearly polarised light of said second type (12).
- 4. An apparatus according to claim 3, wherein said separating means comprises at least one polarising beam splitter (14).
- 5. An apparatus according to any one of the preceding claims, further comprising excitation means (30, 32) for causing said object (2) to emit elliptically polarised light of said first (6) and second (8) types.
- 6. An apparatus according to claim 5, wherein said excitation means comprises at least one light-emitting diode (LED).
- 7. An apparatus according to claim 5 or 6, wherein said excitation means comprises at least one laser (32) and at least one bulb containing xenon (30).
- 8. An apparatus according to any one of claims 5 to 7, wherein said excitation means (30, 32) is adapted to be pulsed.
- 9.A light detecting method comprising: converting elliptically polarised light of a first type (6) emitted by an object (2) into linearly polarised light of a first type (10); converting elliptically polarised light of a second type (8) emitted by said object (2) into linearly polarised light of a second type (12); providing an output signal (28) dependent on an intensity of said linearly polarised light of said first type (10); and providing an output signal (26) dependent on an intensity of said linearly polarised light of said second type (12).
- 10. A method according to claim 9, further comprising separating said linearly polarised light of said first type (10) from said linearly polarised light of said second type (12).
- 11. A method according to claim 9 or 10, further comprising causing said object (2) to emit said elliptically polarised light of said first (6) and second types (8).
- 12. A method according to claim 11, further comprising pulsing excitation means (30, 32) for causing said object (2) to emit said elliptically polarised light of said first (6) and second types (8).
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1507296.0A GB2537870A (en) | 2015-04-29 | 2015-04-29 | Light detecting apparatus |
| PCT/GB2016/051091 WO2016174395A1 (en) | 2015-04-29 | 2016-04-20 | Light detecting apparatus for simultaneously detecting left-and right-handed circularly polarised light |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1507296.0A GB2537870A (en) | 2015-04-29 | 2015-04-29 | Light detecting apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB201507296D0 GB201507296D0 (en) | 2015-06-10 |
| GB2537870A true GB2537870A (en) | 2016-11-02 |
Family
ID=53488846
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1507296.0A Withdrawn GB2537870A (en) | 2015-04-29 | 2015-04-29 | Light detecting apparatus |
Country Status (2)
| Country | Link |
|---|---|
| GB (1) | GB2537870A (en) |
| WO (1) | WO2016174395A1 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4586820A (en) * | 1983-03-31 | 1986-05-06 | Horiba, Ltd. | Apparatus for measuring anisotropy of light emitted from the sample |
| JP2004340833A (en) * | 2003-05-16 | 2004-12-02 | Institute Of Physical & Chemical Research | Optical measuring device |
| WO2012127273A1 (en) * | 2011-03-21 | 2012-09-27 | University Of Calcutta | Apparatus and methods for chirality detection |
-
2015
- 2015-04-29 GB GB1507296.0A patent/GB2537870A/en not_active Withdrawn
-
2016
- 2016-04-20 WO PCT/GB2016/051091 patent/WO2016174395A1/en active Application Filing
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4586820A (en) * | 1983-03-31 | 1986-05-06 | Horiba, Ltd. | Apparatus for measuring anisotropy of light emitted from the sample |
| JP2004340833A (en) * | 2003-05-16 | 2004-12-02 | Institute Of Physical & Chemical Research | Optical measuring device |
| WO2012127273A1 (en) * | 2011-03-21 | 2012-09-27 | University Of Calcutta | Apparatus and methods for chirality detection |
Also Published As
| Publication number | Publication date |
|---|---|
| GB201507296D0 (en) | 2015-06-10 |
| WO2016174395A1 (en) | 2016-11-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |