WO2016000001A1 - Dispositif et procede de mesure du dichroisme circulaire - Google Patents

Dispositif et procede de mesure du dichroisme circulaire Download PDF

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Publication number
WO2016000001A1
WO2016000001A1 PCT/AM2014/000003 AM2014000003W WO2016000001A1 WO 2016000001 A1 WO2016000001 A1 WO 2016000001A1 AM 2014000003 W AM2014000003 W AM 2014000003W WO 2016000001 A1 WO2016000001 A1 WO 2016000001A1
Authority
WO
WIPO (PCT)
Prior art keywords
spectral bandwidth
light
light source
monochromatic
receivers
Prior art date
Application number
PCT/AM2014/000003
Other languages
English (en)
Inventor
Hakob MARGARYAN
Nune HAKOBYAN
David HOVHANNISYAN
Vladimir Aroutiounian
Nelson Tabirian
Upendra ROHATGI
Jae Jo
Oleksandr GOUSHCHA
Tigran SARGSYAN
Petros GASPARYAN
Original Assignee
Margaryan Hakob
Hakobyan Nune
Hovhannisyan David
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 Margaryan Hakob, Hakobyan Nune, Hovhannisyan David filed Critical Margaryan Hakob
Publication of WO2016000001A1 publication Critical patent/WO2016000001A1/fr

Links

Classifications

    • 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
    • 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
    • G01J3/02—Details
    • G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
    • G01J3/0235—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows using means for replacing an element by another, for replacing a filter or a grating
    • 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
    • G01J3/10—Arrangements of light sources specially adapted for spectrometry or colorimetry
    • 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
    • G01J3/30—Measuring the intensity of spectral lines directly on the spectrum itself
    • G01J3/32—Investigating bands of a spectrum in sequence by a single detector

Definitions

  • the invention is related to the field of optical instrumentation design and development, specifically to the design of a spectropolarimeter for measuring circular dichroism (CD) in a wide spectral range.
  • the key element of the spectropolarimeter of the current invention is the liquid crystal polarization diffraction grating (PDG).
  • PDG liquid crystal polarization diffraction grating
  • a tunable monochromator coupled to a wide spectral bandwidth light source, or other monochromatic or narrow spectral bandwidth light source may be placed conventionally in front of the investigated sample to provide CD measurements within the required spectral range.
  • the signal with a high signal/noise ratio is detected using two photodetectors placed at the output of the PDG, connected to downstream electronics and digital processing system.
  • circular dichroism spectroscopy circularly polarized light is being used to examine structural specifics of optically active chiral environment.
  • CD measurements are indispensible in studying biological molecules, their structure and their interaction with other molecules.
  • the absorption spectroscopy technique is being used to measure CD; this technique is based on recording the difference in the absorption strength of the left- and right- circularly polarized beams.
  • the left- and right- circularly polarized components of light passing through the sample are separated using PEM.
  • This technique requires application of a sinusoidal high voltage of e.g. 50 kHz frequency to PEM.
  • a sinusoidal high voltage e.g. 50 kHz frequency
  • two temporally separated components with left- and right- circular polarizations are formed, which requires more time and real estate (downstream electronics) for additional data acquisition and processing of those two signals.
  • PEM-based system is a necessity to record intensities of the right- and left- polarized light at the maximum of the applied sinusoidal voltage.
  • high power (100 Watts or higher) light sources are used in the conventional spectropolarimeters.
  • the spectropolarimeters based on application of PEM have at least two significant drawbacks: -first is a dramatically low efficiency due to inefficient usage of light energy and the second is a significant data acquisition and processing time required to obtain a high signal/noise ratio and, subsequently, to ensure high accuracy of measurements. Obviously, such devices cannot be used for studying of the fast running processes.
  • PDG liquid crystal polarization diffraction grating
  • the device for measuring circular dichroism described in [6] is the device for measuring circular dichroism described in [6]. Its main functional element is the liquid crystal polarization diffraction grating.
  • the grating generates just only two diffracted fields of +1 and -1 orders. The intensities of these two fields are proportional to the intensities of the left- and right- circularly polarized components of light falling on the grating. Note that the light beam may be linearly polarized, not polarized, or randomly polarized.
  • the wide spectral bandwidth light beam passes through the analyzed sample and falls on PDG, which provides spectral decomposition of the incident light.
  • the described above device allows measuring CD in real time within a wide spectral range.
  • This device provides a reasonably high signal/noise ratio allowing simultaneous recording of intensity distributions of the left- and right- circularly polarized components at different wavelengths using CCD/CMOS arrays or similar array detectors.
  • this device does not provide high angular resolution, allowing the accuracy of the CD measurements in the order of a few hundreds of millidegrees (300 mdeg) [7].
  • Such low resolution of CD measurements is pre-determined by the used optical setup, in which the accuracy of the detector arrays' alignment is limited - to get high resolution the special alignment of the detector arrays in such systems has to be of the order of the wavelength of light. Any small spatial misalignment (close enough to the light's wavelength) of the two detector arrays in the direction of the impinging light or perpendicular to it, will produce a false circular dichroism signal.
  • the present invention describes the device and methods that surpasses drawbacks of the conventional devices allowing measuring real-time circular dichroism spectra with high angular resolution and high signal/noise ratio, using the apparatus based on the liquid crystal polarization diffraction grating (LC PDG).
  • LC PDG liquid crystal polarization diffraction grating
  • the principal objective/embodiment of the present invention is to propose a spectropolarimeter based on PDG and method for real-time measurements of circular dichroism, with high angular resolution and high signal/noise ratio.
  • the other embodiments of the present invention include the spectral polarimeter based on PDG in which:
  • a monochromatic or narrow spectral bandwidth light is used to probe the sample
  • a broadband spectrum xenon lamp may be used as a light source; a fixed light wavelength (or a narrow spectral bandwidth beam) is selected using the monochromator placed between the light source and the investigated sample;
  • - CD measurements in the wide spectral range may be provided by scanning of the light wavelength using the monochromator;
  • each of the two detectors may have multiple active areas, but the output of either all active areas or limited number of active areas of each of the two detectors may be connected in parallel to detect the signals;
  • the signal recording is realized on the fixed wavelength, allowing to circumvent the requirement for the accuracy of alignment of the two detector arrays, which requirement is typical for the conventional CD devices;
  • - CD measurements may be provided at a fixed wavelength, eliminating the need of a xenon lamp and monochromator.
  • the possible version of such measurements may include light emitting diode (LED) emitting the required light wavelength or other monochromatic or narrow bandwidth light source known in the industry.
  • LED light emitting diode
  • the present invention proposes the apparatus and method for measuring CD spectra, comprising the steps of irradiating the sample with a monochromatic or narrow spectral bandwidth light, dispersing/diffracting the light that passes through the sample into the right- and left- circular polarized components by using the polarization diffraction grating, detecting the light intensity of the two light beams by the two single active area detectors (one single-active area detector per beam), and then measuring a circular dichroism spectrum of the sample on the basis of a result of the detection by the two detectors.
  • the CD measurements are virtually of a real-time type and the angular resolution (CD resolution) if not dependent on the alignment of the detectors, since the CD signal is measured by providing simultaneous readouts from the two single active area detectors. Therefore, the apparatus and method according to the present invention enables a wide variety of applications, in which high CD angular resolution, high signal-to-noise ratio, and real-time signal monitoring is important.
  • the monochromatic light beam from the output of a monochromator passes through the sample, and the said light beam successively passes through LC PDG.
  • the two diffracted monochromatic beams are detected by the two high sensitive, single-active area photodetectors.
  • the output currents from the two photodetectors are supplied to the inputs of differential logarithmic impedance amplifier.
  • the output signals from the photodetectors can be recorded by any other downstream electronics, and may be further followed by digitizing.
  • the monochromatic light sources like lasers, known in the industry may be used as the source to irradiate the sample.
  • the monochromatic light sources like lasers, known in the industry may be used as the source to irradiate the sample.
  • either the narrow spectral bandwidth light emitting diodes (LED) or narrow bandwidth interference filters (or other spectral selective filters) may be used.
  • the important parameter for CD calculations is
  • Ii and I 2 are the intensities of the left- and right- circularly polarized beams at a fixed wavelength, recorded by the two photodetectors.
  • CD is determined using the following formula:
  • IOL and 1 ⁇ 2 are the reference values of the intensities of the left- and right- circularly polarized beams, when e.g. the distilled water or other known industry standard is used as a sample
  • ITL and ITR are the intensities of the left- and right- circularly polarized components of beam passed through the sample and spatially separated by PDG.
  • the output signal from the downstream electronic devices e.g. the logarithmic amplifier
  • CD value is calculated using the intensity ratio of the two diffracted beams.
  • a quartz cuvette is used for a sample placement. If the front and back walls of the cuvette are not perfectly parallel, the additional systematic error of CD measurement will be added. In order to take into account this error, the intensities of the left- and right- circularly polarized components of the beam passed through an empty cuvette and spatially separated by PDG are measured independently or in advance. In some embodiments, this systematic error is being accounted for using the software during data collection and processing.
  • Fig. l The optical block-schematics of the proposed devise in accord with one of the embodiments of the current invention, in which an optical element that spatially separates the optical beam into the left- and right-hand circularly polarized monochromatic or narrow spectral bandwidth components is used, and the light source is a monochromatic or narrow spectral- bandwidth beam.
  • FIG.2 A part of the optical block-schematics of the proposed devise in accord with the other embodiments of the current invention, in which a narrow spectral bandwidth LED is used as the light source.
  • FIG.3 A part of the optical block-schematics of the proposed devise in accord with the other embodiments of the current invention, in which a wide spectral bandwidth light source coupled to narrow band pass filters are used.
  • FIG.4 A part of the optical block-schematics of the proposed devise in accord with the other embodiments of the current invention, in which a monochromatic laser is used as the light source.
  • a monochromatic or narrow spectral bandwidth light beam is formed from a wide spectral bandwidth light source, for example a xenon lamp (1), using a monochromator (2).
  • This monochromatic or narrow spectral bandwidth light beam is being directed to a cuvette with the sample (3).
  • the beam passing through the sample with CD is being spatially separated by the optical element (4) into the left- and right-hand circularly polarized monochromatic or narrow spectral bandwidth components.
  • the liquid crystal polarization diffraction grating (LC PDG) can serve as an optical element (4).
  • the intensities of those components are being recorded by the two single-active area photoreceivers/photodetectors (5).
  • the photocurrents from the two photoreceivers/photodetectors (5) are recorded by the downstream electronics (6) that as an example only may include a differential logarithmic impedance amplifier or other relevant amplification device.
  • the amplified signal is sent to the computer (7) or an alternative processing unit, where further processing of the recorded data takes place using specially designed software.
  • Fig.2, Fig.3, Fig.4 show few other types of light sources operating at certain specific wavelengths or within a narrow spectral bandwidth that can be used instead of the wide spectral bandwidth light source coupled to a monochromator in the current invention.
  • Fig.2 shows the LED (8), the output beam from which enters the sample.
  • Fig.3 shows a white light source (9) coupled to narrow spectral bandwidth filters (10).
  • Fig.4 shows a laser operating at the required light wavelengths (11). The light beam from laser enters the sample.
  • the proposed device and method therein allows recording the intensities of the right- and left- circularly polarized components of the light beam passed through the sample and spatially separated by PDG using sensitive photoreceivers at fixed wavelengths or within narrow spectral wavelengths intervals.
  • the difference in photocurrents, which is proportional to sample's CD, is being measured using e.g. a differential logarithmic impedance amplifier.
  • Measurement results are being processed using specially designed software.
  • the wavelength is being changed by a monochromator, which is placed before the sample, in order to insure the required spectral range.
  • any other known in the industry method to provide either monochromatic or narrow spectral bandwidth light could be used.
  • the proposed device and methods may be used for measuring CD at certain specific wavelengths or within a narrow spectral bandwidth.
  • the white source of light e.g. a xenon lamp
  • LEDs of the necessary light wavelengths may be used as a light source, while the monochromator is eliminated from the optical scheme.
  • various spectral filters color glasses, multilayer dielectric filters, or other known in the industry spectral filters

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  • 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)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

L'invention concerne un dispositif permettant de mesurer un spectre de dichroïsme circulaire (CD). L'élément clé du dispositif de la présente invention est le réseau de diffraction (4) de polarisation à cristaux liquides. On utilise la différence d'absorption de la lumière monochromatique polarisée circulairement à gauche et à droite pour mesurer le CD. Un monochromateur (2) accordable couplé à une source lumineuse à largeur de bande spectrale large, ou à une autre source lumineuse monochromatique ou à largeur de bande spectrale étroite, est placé en face de l'échantillon examiné (3) pour fournir des mesures du CD dans la plage spectrale requise. Le signal présentant un rapport signal/bruit élevé est détecté au moyen de deux photodétecteurs (5) à zone active unique placés au niveau de la sortie du réseau de diffraction de polarisation, qui sont connectés à des systèmes électroniques (6) en aval et à un système (7) de traitement numérique. Les mesures de CD obtenues présentent une résolution supérieure ou égale à 3-5 millidegrés.
PCT/AM2014/000003 2014-07-01 2014-11-18 Dispositif et procede de mesure du dichroisme circulaire WO2016000001A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AMAM20140082 2014-07-01
AM20140082 2014-07-01

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WO2016000001A1 true WO2016000001A1 (fr) 2016-01-07

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170003169A1 (en) * 2015-07-05 2017-01-05 Purdue Research Foundation Sub-millimeter real-time circular dichroism spectrometer with metasurfaces
US9920545B2 (en) 2013-10-13 2018-03-20 Maytronics Ltd. Autonomous pool cleaning robot
JP6351893B1 (ja) * 2018-02-26 2018-07-04 日本分光株式会社 位相差制御装置
WO2019111800A1 (fr) * 2017-12-07 2019-06-13 横河電機株式会社 Analyseur spectroscopique
US12007276B2 (en) 2018-03-22 2024-06-11 Purdue Research Foundation Sensor for hyperspectral imaging based on a metasurface-integrated light detector array

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004340833A (ja) * 2003-05-16 2004-12-02 Institute Of Physical & Chemical Research 光学測定装置

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004340833A (ja) * 2003-05-16 2004-12-02 Institute Of Physical & Chemical Research 光学測定装置

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
A. MAZZULLA ET AL: "Real-Time Circular Dichroism Spectrograph Based on a Single Liquid Crystal Diffractive Element", MOLECULAR CRYSTALS AND LIQUID CRYSTALS, vol. 516, no. 1, 5 February 2010 (2010-02-05), pages 233 - 239, XP055176714, ISSN: 1542-1406, DOI: 10.1080/15421400903409473 *
L NIKOLOVA ET AL: "SPECTROPHOTOPOLARIMETER: A SIMPLIFIED VERSION FOR REAL TIME MEASUREMENT AT SELECTED WAVELENGTHS", BULGARIAN JOURNAL OF PHYSICS, 1 January 1993 (1993-01-01), pages 46 - 54, XP055176837, Retrieved from the Internet <URL:http://mario294.tripod.com/profbio/polarim.pdf> [retrieved on 20150316] *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9920545B2 (en) 2013-10-13 2018-03-20 Maytronics Ltd. Autonomous pool cleaning robot
US20170003169A1 (en) * 2015-07-05 2017-01-05 Purdue Research Foundation Sub-millimeter real-time circular dichroism spectrometer with metasurfaces
US10161797B2 (en) * 2015-07-05 2018-12-25 Purdue Research Foundation Sub-millimeter real-time circular dichroism spectrometer with metasurfaces
US20190219447A1 (en) * 2015-07-05 2019-07-18 Purdue Research Foundation Sub-millimeter real-time circular dichroism spectrometer with metasurfaces
US10760970B2 (en) * 2015-07-05 2020-09-01 Purdue Research Foundation Sub-millimeter real-time circular dichroism spectrometer with metasurfaces
WO2019111800A1 (fr) * 2017-12-07 2019-06-13 横河電機株式会社 Analyseur spectroscopique
JPWO2019111800A1 (ja) * 2017-12-07 2020-09-03 横河電機株式会社 分光分析装置
JP6351893B1 (ja) * 2018-02-26 2018-07-04 日本分光株式会社 位相差制御装置
JP2019148430A (ja) * 2018-02-26 2019-09-05 日本分光株式会社 位相差制御装置
US12007276B2 (en) 2018-03-22 2024-06-11 Purdue Research Foundation Sensor for hyperspectral imaging based on a metasurface-integrated light detector array

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