KR101290703B1 - Apparatus and method for detecting optical activity using self-heterodyned detection technique - Google Patents

Abstract

An optical activity measuring device includes a light source unit for irradiating a white light pulse signal; A polarization controller configured to adjust the polarization of the white light pulse signal to generate incident light including a pump light in a first polarization direction and a reference light in a second polarization direction, and to incident the incident light on a sample having a chiral property; A polarization beam splitter that separates the incident light passing through the sample into a first component in the first polarization direction and a second component in the second polarization direction; And a detector configured to measure the optical activity of the sample by using the first component and the second component. Using an optical activity measuring device, self-heterodyned detection of circular dichroism and optical rotatory dispersion over a wide band from the ultraviolet to the visible range can do.

Description

Apparatus and method for measuring optical activity using self-heterodyne detection {APPARATUS AND METHOD FOR DETECTING OPTICAL ACTIVITY USING SELF-HETERODYNED DETECTION TECHNIQUE}

Examples relate to an optical activity measuring apparatus and method. Specifically, embodiments use self-heterodyned detection to measure circular dichroism and optical rotatory dispersion, etc., in the broadband from the ultraviolet region to the visible region. It relates to an optical activity measuring apparatus and method that can be.

Optically active spectroscopy, such as circular dichroism (CD) and optical rotatory dispersion (ORD), are very sensitive to molecular structure, making them very useful for structural analysis of chiral molecules, including biomolecules. Do. However, because optically active signals are very weak, their application in time domain spectroscopy is not easy.

The optical activity signal is dependent on the difference in response (e.g. absorption or refractive index difference) between chiral properties of the sample with left circularly polarized light (LCP) and right circularly polarized light (RCP). Caused by Therefore, the general optical activity measurement uses a differential method that alternately irradiates the left and right circularly polarized light on the sample and measures the difference, which is then scanned according to the wavelength.

Another method for detecting an optically active signal is a heterodyne measurement, in which an optically active signal is measured by interfering with a reference signal. In the case of heterodyne measurement, the signal-to-noise ratio of the measurement increases in proportion to the magnitude of the reference signal, and since the measurement is performed in the time domain, there is no need to perform a scan, thereby shortening the measurement time. For example, Korean Patent Publication No. 10-2010-91280 discloses a technique for measuring CD and ORD spectra of femtoseconds.

In order to measure the optically active signal in the electron transfer process of the biomolecule, it is required to measure the optically active signal in the ultraviolet and / or visible light region. However, in the conventional method of measuring an optically active signal using interference with an externally generated reference signal, the interference signal to be detected is very sensitive to the phase relationship between the signals. As a result, the method has a problem in that it is difficult to apply because the influence of the variation of the phase relationship on the result is very large in the ultraviolet and / or visible light region having a short wavelength.

According to an aspect of the present invention, it is possible to provide an optical activity measuring apparatus and method capable of measuring optical activity of a sample even in the ultraviolet and / or visible light region without noise due to phase difference.

An optical activity measuring apparatus according to an embodiment includes a light source unit for irradiating a white light pulse signal; A polarization controller configured to adjust the polarization of the white light pulse signal to generate incident light including a pump light in a first polarization direction and a reference light in a second polarization direction, and to incident the incident light on a sample having a chiral property; A polarization beam splitter that separates the incident light passing through the sample into a first component in the first polarization direction and a second component in the second polarization direction; And a detector configured to measure the optical activity of the sample by using the first component and the second component.

According to one or more exemplary embodiments, an optical activity measuring method includes: generating incident light including a pump light in a first polarization direction and a reference light in a second polarization direction by adjusting polarization of a white light pulse signal; Injecting the incident light into a sample having chiral properties; Separating the incident light passing through the sample into a first component in the first polarization direction and a second component in the second polarization direction; And measuring the optical activity of the sample using the first component and the second component.

According to the optical activity measuring apparatus and method according to an aspect of the present invention, since incident light itself is used for excitation and interference of a sample without separately generating a reference light for heterodyne detection, the optical activity signal and the reference signal The movement path is the same. Therefore, it is possible to fundamentally remove the uncertainty of the phase relationship and to measure the optical activity spectrum in the broadband from the near ultraviolet region to the visible region.

In addition, according to the optical activity measuring apparatus and method, it is possible to selectively measure the circular dichroism (CD) and optical rotatory dispersion (ORD) signals by adjusting the polarization state of the incident light to the sample have. In particular, unlike the conventional method of changing the polarization state of incident light during measurement, one fixed polarization state can be used, so that the optically active signal can be measured by the non-differential measurement method with only one laser pulse.

Furthermore, the optical activity measuring device measures and computes two polarized components separated from one pulse simultaneously with a charge coupled device (CCD) detector, so that the measurement stability is high and the device configuration is simple. In addition, automatic correction of output intensity fluctuations of the light source is possible. In addition, high repetition rate measurements are possible and the entire spectrum can be obtained directly without a scanning method, thereby increasing the quality of the spectrum at high measurement rates.

When the optical activity measuring apparatus and method according to an aspect of the present invention is applied to time domain spectroscopy, the time resolution of the measurement is increased to the femtosecond level to be used for the dynamical study of the optical activity of biochemical molecules occurring at a very high speed. It is possible to extend to multidimensional spectroscopy.

1 is a schematic diagram of an optical activity measuring device according to one embodiment.
2A is a graph illustrating a measurement result of a circular dichroism (CD) signal by an optical activity measuring apparatus according to an exemplary embodiment.
2B is a graph illustrating optical rotatory dispersion (ORD) signal measurement results by an optical activity measuring apparatus according to an exemplary embodiment.
3 is a graph illustrating a measurement result of an ORD signal according to the number of pulses in an optical activity measuring apparatus according to an embodiment.
4A illustrates an amplified ORD signal measured using incident light having a center wavelength of about 400 nm in the optical activity measuring device according to one embodiment.
FIG. 4B shows the signal-to-noise ratio calculated from the ORD signal shown in FIG. 4A.
5 is a graph illustrating a result of measuring a CD signal and an ORD signal for a spiral aggregate using an optical activity measuring apparatus according to an embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Samples with chiral properties absorb left-circular polarized (LCP) light and right-circular polarized light (RCP) light differently, which is the difference in light due to the optical activity of the sample. As the susceptibility (differential susceptibility) can be represented by the following equation (1).

은 좌원편광된 빛의 감수율

및 우원편광된 빛의 감수율

의 차로 표현될 수 있다. 차등 감수율은 복소수의 성질을 가지며, 실수부는 광 회전 분산(optical rotatory dispersion; ORD) 신호에 해당하고 허수부는 원편광 이색성(circular dichroism; CD) 신호에 해당된다. As shown in Equation 1, the differential susceptibility at the frequency ω

Susceptibility of Left Circle Polarized Light

And unipolar polarization of light

Can be expressed as The differential susceptibility has a complex number, the real part corresponds to an optical rotatory dispersion (ORD) signal and the imaginary part corresponds to a circular dichroism (CD) signal.

Linearly polarized light can be viewed as the sum of 50% left circularly polarized light component and 50% right circularly polarized light component. When the linearly polarized light passes through the sample having chiral properties, the polarization of the incident light is changed to the rotated elliptical polarization due to the difference in the reaction between the left circularly polarized component and the right circularly polarized component. In this case, the CD and / or ORD signal may be measured using a ratio of parallel and orthogonal components to light passing through the sample.

는 시료를 통과한 빛 중 시료에 대한 입사광의 편광의 주축 방향과 평행한 방향(예컨대, 수직 방향)의 성분을 나타낸다.

는 시료를 통과한 빛 중 입사광의 편광의 주축과 직교하는 방향(예컨대, 수평 방향)의 성분을 나타내는 것으로서, 입사광으로 인해 시료로부터 생성된 광학 활성 신호에 대응된다. 또한, 상기 수학식 2에서 L은 시료를 통과하는 광 경로의 길이를 나타내며, c는 빛의 속도를 나타내고, n(ω)는 시료의 굴절률을 나타낸다. In Equation (2)

Denotes a component in a direction parallel to the main axis direction of the polarization of the incident light with respect to the sample among the light passing through the sample.

Represents a component in a direction (eg, a horizontal direction) orthogonal to the main axis of polarization of incident light among the light passing through the sample, and corresponds to an optically active signal generated from the sample due to the incident light. In Equation 2, L represents the length of the optical path through the sample, c represents the speed of light, n (ω) represents the refractive index of the sample.

과

의 비율에 대하여 다음 수학식 3 및 수학식 4와 같이 표현될 수 있다. When the equation 2 is divided into a real part and an imaginary part, the CD signal and the ORD signal are

and

The ratio of may be expressed as Equation 3 and Equation 4 below.

는 CD 신호를 나타내며,

는 ORD 신호를 나타낸다. 또한, 상기 수학식 3 및 수학식 4에서

및

은 각각 차등 흡수율 및 차등 굴절률에 해당하는 항들로서, 각각 다음의 수학식 5 및 수학식 6과 같이 표현될 수 있다. In Equations 3 and 4

Represents the CD signal,

Indicates an ORD signal. In addition, in Equations 3 and 4

And

Are terms corresponding to the differential absorption rate and the differential refractive index, respectively, and may be expressed as Equations 5 and 6, respectively.

및

의 비율인

의 위상과 세기가 측정되면, 수학식 3 내지 수학식 6을 이용하여 CD 신호 및 ORD 신호 중 원하는 신호를 측정할 수 있다. 이상의 측정 과정을 수행할 수 있는 일 실시예에 따른 광학 활성 측정 장치 및 방법에 대하여 이하에서 상세히 설명한다.
Therefore, in the signal passing through the sample

And

Which is the ratio of

When the phase and the intensity of is measured, the desired signal of the CD signal and the ORD signal can be measured using Equations 3 to 6. An optical activity measuring apparatus and method according to an embodiment capable of performing the above measurement process will be described in detail below.

1 is a schematic diagram of an optical activity measuring device according to one embodiment.

Referring to FIG. 1, an optical activity measuring apparatus according to an embodiment may include a light source unit 10, a polarization control unit 20, a polarizing beam splitter 40, and a detector 50. Light may be irradiated to the sample 30 having chiral properties using the light source unit 10 and the polarization control unit 20, and the light passing through the sample 30 may be irradiated in each direction using the polarization beam splitter 40. After separation into the components of, by detecting the separated components in the detection unit 50 can measure the optical activity signal of the sample (30).

The light source unit 10 may include a laser light source 101 and a sample cuvette 102. The femtosecond laser pulses may be focused onto the sample cuvette 102 using the laser light source 101. In one embodiment, the femtosecond laser pulses may have a center wavelength of about 800 nm. The sample cuvette 102 may contain water. Sample cuvette 102 may have a length of about 1 cm. When femtosecond laser pulses are irradiated with water, white light pulses may be generated from the water. By adjusting the intensity and / or focal length of the laser pulse focused on the water, the white light pulse can be stabilized without fluctuations from the near ultraviolet region to the visible region. In one embodiment, the white light pulse may have a wavelength range from about 380 nm to about 750 nm.

The spectrum shown at the top of the sample cuvette 102 in FIG. 1 represents the result of detecting the white light pulse by the CCD detector 503. In the spectrum, the horizontal axis represents wavelength (nm), and the vertical axis represents a value obtained by digitizing light intensity in a range of at least 0 to at most 2 ¹⁶ counts. Further, in the spectrum, track 1 and track 2 are spectra corresponding to light detected in two different regions of the CCD detector 503, which will be described later in detail with respect to the CCD detector 503.

The generated white light pulse may be incident on the sample 30 through the polarization control unit 20. The polarization controller 20 may adjust the polarization of the incident light to be incident on the sample 30 according to the type of the signal to be measured. For example, when the CD signal is to be measured, incident light having elliptical polarization may be incident on the sample 30. In addition, when the ORD signal is to be measured, incident light having rotated linearly polarized light may be incident on the sample 30. The polarization control unit 20 may include one or more means for controlling the polarization of the white light pulse.

The polarization control unit 20 generates incident light to be incident on the sample 30 by adjusting the polarization of the white light pulse, but may adjust the polarization of the white light pulse so that the incident light has a component in the first polarization direction and a component in the second polarization direction. have. The first polarization direction and the second polarization direction may be directions perpendicular to each other. In addition, a component having a relatively high intensity in incident light may correspond to a component in the first polarization direction, and a component having a relatively low intensity may correspond to a component in the second polarization direction. In the present specification, the component in the first direction of the incident light incident on the sample 30 is referred to as pump light, and the second component is referred to as reference light.

For example, when the ORD signal is to be measured using the optical activity measuring device, the polarization controller 20 may include a polarizer 201. The alignment direction of the polarizer 201 may be disposed to rotate at a predetermined angle from the vertical direction. The predetermined angle may be determined such that the component in the vertical direction in the light passing through the polarizer 201 has a relatively large intensity compared to the component in the horizontal direction. The white light pulse passing through the polarizer 201 configured as described above has a rotated linear polarized light, which may be divided into a vertical component and a horizontal component. At this time, the component in the vertical direction corresponds to the pump light, and the component in the horizontal direction corresponds to the reference light.

In one embodiment, the polarizer 201 may have an orientation direction rotated by about 5 ° from the vertical direction. In this case, the horizontal component in the white light pulse passing through the polarizer 201 may be maintained at an intensity of about 1/100 of the vertical component. Since the light intensity is proportional to the square of the electric field, when the intensity of the horizontal component is adjusted to 1/100 of the vertical component, the ratio of the pump light and the reference light is 1/10 of the incident light incident on the sample 30. Therefore, a 10 times amplification effect can be obtained with respect to the CD signal and / or the ORD signal measured as described later with reference to Equation (12). However, the above values are merely exemplary, and the angle in the orientation direction of the polarizer 201 may be determined differently in consideration of the degree of amplification of the signal.

In addition, when the CD signal is to be measured using the optically active device, the polarization control unit 20 may include a strain plate 202. The tension plate 202 may be pressurized from an angle at which the pressure is applied at a plane perpendicular to the path of light while the main axis of polarization does not rotate. The angle at which pressure is applied to the tension plate 202 may be an angle of about 45 ° with respect to the vertical direction. As a result, the polarization of the white light pulse passing through the tension plate 202 can be converted into elliptical polarization having a long axis in the vertical direction and a short axis in the horizontal direction. In this case, the long-axis component corresponds to the pump light and the short-axis component corresponds to the reference light in the elliptically polarized light.

In one embodiment, the pressure applied to the tension plate 202 may be adjusted such that the ratio of the intensity of the major axis component to that of the minor axis component in the elliptical polarized light is about 100: 1. As a result, in the same manner as described above with respect to the polarizer 201, a 10 times amplification effect can be obtained for the CD signal and / or the ORD signal to be measured. This will be described later in detail with reference to Equation.

In the above-described embodiments, the case where the vertical direction is used as the polarization direction of the pump light and the horizontal direction is used as the polarization direction of the reference light in adjusting the polarization of the white light pulse using the polarizer 201 or the tension plate 202 has been described. . However, this is merely illustrative, and the polarization direction of the pump light is not necessarily limited to the vertical direction but may be determined in other different directions.

On the other hand, one or more slits 801, 802, mirrors 601, 602 while light emitted from the light source 101 travels through the sample cuvette 102, the polarizer 201 and / or the tension plate 202. And light propagation paths using the lenses 701 and 702. However, the number and arrangement of the one or more slits 801, 802, the mirrors 601, 602, and the lenses 701, 702 shown in FIG. 1 are merely exemplary, and these elements may adjust the direction of light. In order to be irradiated to the sample 30 may have a different number and / or arrangement than that shown in the drawings, and may further include one or more other elements not shown, or one or more of the elements shown may be omitted. It may be.

Polarization is controlled by the polarizer 201 and / or the tension plate 202 so that a white light pulse including the pump light and the reference light is incident on the sample 30 as incident light. The sample 30 may include a material having chiral properties. For example, sample 30 may be nickel-tartrate ₂ or other suitable organometallic compound. Alternatively, the sample 30 may be a spiral aggregate of dye molecules.

When incident light including the pump light and the reference light is incident on the sample 30, an optically active signal having a polarization direction perpendicular to the pump light may be generated by the pump light due to the chiral nature of the sample 30. As a result, the polarization of the incident light is changed to elliptical polarization in which the main axis is rotated. On the other hand, the reference light having a polarization direction orthogonal to the polarization direction of the pump light may amplify the optically active signal by the self-heterodyne interference after passing through the sample 30. According to the phase relationship between the pump light and the optically active signal, circularly polarized dichroism or optical rotation dispersion signal can be selectively detected.

Since the optically active signal and the reference light travel along the same optical movement path, a constant phase relationship can always be maintained between the optically active signal and the reference light. Therefore, it is possible to fundamentally remove the uncertainty of the phase relationship, and to measure the optical activity spectrum even in a short wavelength region such as an ultraviolet ray and / or a visible ray region.

The polarization beam splitter 40 has a component in a direction parallel to the polarization direction of the pump light (for example, the vertical direction) and a component in a direction orthogonal to the polarization direction of the pump light (for example, the horizontal direction) of the light passing through the sample 30. To separate. In this specification, the component of the direction parallel to the polarization direction of pump light is called parallel component, and the component orthogonal to the polarization direction of pump light is called orthogonal component. Parallel components and orthogonal components separated by the polarizing beam splitter 40 may be transmitted to the detector 50 in independent paths, respectively.

The detector 50 may include a monochromator 502 and a charge coupled device (CCD) detector 503. Each component separated in polarizing beam splitter 40 may be delivered to monochromator 502 via mirrors 603, 604, lenses 703, and the like. The monochromator 502 distributes the light passing through the sample 30 according to the wavelength and transmits the light to the CCD detector 503. In the CCD detector 503, parallel and quadrature components are received through the monochromator 502. At this time, the traveling direction of the parallel component and the orthogonal component is the same as seen from the CCD detector 503, but since the difference is only in the height, the parallel component and the orthogonal component can be spatially separated.

For example, the CCD detector 503 may be configured in which fine photodetectors are arranged in a lattice form. In this case, the entire array of light detecting elements is not necessarily used for light detection, and an area to be used may be arbitrarily determined. For example, when the CCD detector 503 is divided into two parts above and below, the CCD detector 503 operates like two CCD chips arranged up and down. Accordingly, the CCD detector 503 can be divided into regions to detect parallel and orthogonal components in separate regions.

The spectrum shown at the top of the sample cuvette 102 in FIG. 1 shows the spectrum of the white light pulses as separate tracks (track 1 and track 2), respectively, according to the detection area at the CCD detector 503. In addition, the spectrum shown at the top of the CCD detector 503 in FIG. 1 represents the spectra of each of the parallel and quadrature components detected spatially separated by the CCD detector 503. The representation of the image of the spectrum in a long elliptic shape in one direction indicates that white light pulses are dispersed according to the wavelength while passing through the monochromator 502.

In the CCD detector 503, the CD and / or ORD signals of the sample 30 may be measured using the strengths of the received parallel and quadrature components. At this time, the parallel and orthogonal components received by the CCD detector 503 are generated from one pulse irradiated from the light source 101 and these components can be measured simultaneously in the CCD detector 503. Therefore, the error according to the intensity fluctuations of the light source 101 can be automatically corrected. In addition, since the recording of the spectrum detected by the CCD detector 503 can be made every pulse, when the operation speed of the CCD detector 503 is high, the same level of measurement as the laser pulse repetition speed of the light source 101 can be measured. For example, a laser repetition rate of about 200 Hz can be maintained in the light source 101, and about 200 measurements can be made per second using the light source 101.

Hereinafter, the CD signal and / or the ORD signal of the sample 30 are measured by detecting each component separated by the polarization beam splitter 40 from the light passing through the sample 30 and the respective components by the detector 50. The process of doing this will be described in more detail.

라 하며, 시료(30)를 통과한 기준광의 전기장을 E_LO라 하면, 시료(30)를 통과한 빛에서 총 직교 성분은

가 된다. 또한, 시료(30)를 통과한 빛에서 평행 성분은

로 나타내기로 한다. 이때, 시료(30)를 통과한 빛에서 평행 성분의 세기와 직교 성분의 세기의 비율은 다음 수학식 7과 같이 표현될 수 있다. The electric field of the optically active signal generated from the sample 30

If the electric field of the reference light passing through the sample 30 is E _LO , the total orthogonal component is obtained from the light passing through the sample 30.

. In addition, the parallel component in the light passing through the sample 30

It is represented by. In this case, the ratio of the intensity of the parallel component and the intensity of the orthogonal component in the light passing through the sample 30 may be expressed by Equation 7 below.

는 시료(30)를 통과한 빛에서 직교 성분의 세기를 나타내는 스펙트럼(spectrum)이며,

는 시료(30)를 통과한 빛에서 평행 성분의 세기를 나타내는 스펙트럼이다. 한편, 광학 활성 신호는 기준광과 비교하여 매우 작기 때문에 그 제곱 항은 더 작게 되며, 따라서, 상기 수학식 7의 분자에서

는 무시할 수도 있다. 또한, 입사광에서 펌프광의 전기장 E_V 및 기준광의 전기장 E_H 사이의 비는 다음 수학식 8과 같이 정의될 수 있다.In Equation 7

Is a spectrum representing the intensity of the orthogonal component in the light passing through the sample 30,

Is a spectrum representing the intensity of the parallel component in the light passing through the sample 30. On the other hand, since the optically active signal is very small compared to the reference light, the squared term is made smaller, and therefore, in the molecule of Equation 7

Can be ignored. In addition, the ratio between the electric field E _V of the pump light and the electric field E _{H of the} reference light in incident light may be defined as in Equation 8 below.

은 다음 수학식 9를 만족한다.In addition, the electric field of the optically active signal

Satisfies the following equation (9).

Using Equations 8 and 9, Equation 7 may be converted to Equation 10 below.

는 시료(30)를 통과한 빛에서 평행 성분

의 위상

과 기준광

의 위상

사이의 차이며, 이는 곧 입사광에서 펌프광의 위상

과 기준광의 위상

사이의 차로서 다음 수학식 11과 같이 표현될 수 있다.In Equation 10

Is the parallel component in the light passing through the sample 30.

Phase of

And reference light

Phase of

Is the difference between the phases of the pump light in incident light

And phase of reference light

As a difference between them, the following equation (11) can be expressed.

In one embodiment, the detector 50 may include a neutral density filter 501 optically coupled between the polarizing beam splitter 40 and the monochromator 502. Since the parallel component is relatively strong in the light passing through the sample 30, the neutral filter 501 can be used to weaken the strength of the parallel component. For example, the strength of the parallel component can be weakened to a similar extent as the orthogonal component. The strength of the weakened parallel component can be expressed by Equation 12 below.

Using Equation 12, Equation 10 may be converted into Equation 13 below.

Since the size of the second right term in Equation 13 is much smaller than 1, the log value of Equation 13 may be approximated as in Equation 14 below.

와 E_LO 사이의 위상차는 90°(즉, π/2)이며, 입사광이 회전된 선형 편광을 갖는 경우

와 E_LO 사이의 위상차는 0°이다. 따라서, 상기 수학식 14에서 위상차

는 입사광의 편광 상태에 따라 알 수 있다. 따라서, 상기 수학식 14를 이용하여 그 위상차가 90°일 때는 CD신호를, 0°일 때는 ORD 신호를 측정할 수 있다.When incident light has elliptical polarization

And the phase difference between and E _LO is 90 ° (ie π / 2), and the incident light has rotated linearly polarized light

The phase difference between and E _LO is 0 °. Therefore, the phase difference in Equation 14

It can be known according to the polarization state of the incident light. Accordingly, the CD signal may be measured when the phase difference is 90 ° and the ORD signal when the phase difference is 0 ° using Equation (14).

의 값은 i가 된다. 이때 수학식 14의 우변의 괄호 안에 있는 값 중에서 실수부는

에 비례하는 값으로서 오로지 CD 신호에만 해당된다. 반대로, 입사광이 회전된 선형 편광을 갖는 경우 펌프광과 기준광의 위상차는 0°이므로 상기 수학식 14에서

의 값은 1이 된다. 이때 수학식 14의 우변의 괄호 안에 있는 값 중에서 실수부는

에 비례하는 값으로서 오로지 ORD 신호에만 해당된다.That is, when the incident light has elliptical polarization, the phase difference between the pump light and the reference light is always 90 ° (that is, π / 2), and thus the right side of Equation 14

The value of i becomes i. At this time, the real part of the values in the parentheses of the right side of Equation 14

A value proportional to, only for CD signals. On the contrary, when the incident light has rotated linearly polarized light, the phase difference between the pump light and the reference light is 0 °.

The value of 1 is 1. At this time, the real part of the values in the parentheses of the right side of Equation 14

A value proportional to, only for ORD signal.

In addition, as described in Equation 14, the ratio between the intensity of the orthogonal component and the parallel component in the light passing through the sample 30 is inversely proportional to θ, which is the ratio between the pump light and the reference light in incident light incident on the sample 30. . Therefore, for example, by adjusting the polarization of the incident light so that the reference light becomes 1/10 of the pump light, a 10 times amplification effect can be obtained with respect to the signal to be measured.

2A is a graph illustrating a CD signal measurement result by an optical activity measuring apparatus, and FIG. 2B is a graph illustrating a ORD signal measurement result by an optical activity measuring apparatus, according to an exemplary embodiment. 2A and 2B show the results of measuring CD and ORD using two optical isomers of (+) and (-) of Ni- (tartrate) ₂ molecules.

Referring to FIG. 2A, the graphs 1001 and 1002 respectively show CD signals of Ni-(+)-(tartrate) ₂ and Ni-(-)-(tartrate) ₂ using the optical activity measuring device according to one embodiment. The result of the measurement is shown. On the other hand, the graphs 1003 and 1004 show the results of measuring the CD signal by the conventional measuring method for the same sample for comparison. As shown, it can be seen that the optically active device according to the embodiment shows a measurement aspect similar to that of the conventional method, thereby making normal measurements.

Referring to FIG. 2B, graphs 1005, 1006, and 1007 show an optical activity measuring device according to one embodiment for Ni-(+)-(tartrate) ₂ of about 45 mM, about 22.5 mM, and about 9 mM, respectively. The result of measuring ORD signal by using Meanwhile, the graphs 1009, 1010, and 1011 show ORD signals using an optical activity measuring device according to one embodiment for Ni-(-)-(tartrate) ₂ of about 45 mM, about 22.5 mM, and about 9 mM, respectively. The result of the measurement is shown. Also, graph 1008 represents the ORD signal measured in a conventional manner of scanning with varying polarizer angles. As shown, it can be seen that the measurement result of the optically active device according to one embodiment is quantitatively matched with the measurement result by the conventional method, thereby making normal measurement.

3 is a graph illustrating a measurement result of an ORD signal according to the number of pulses in an optical activity measuring apparatus according to an embodiment.

Referring to FIG. 3, graphs 2001, 2002, 2003, and 2004 show ORD signals measured using 1 pulse, 10 pulses, 100 pulses, and 1000 pulses, respectively. For example, the measurement time when 100 pulses were used was about 0.5 second. As shown, it can be seen that a sufficient level of measurement is possible in the case of the graph 2003 measured using 100 pulses. In the graph (2001) measured using one pulse, the noise caused by the device is not canceled, but the phase for any chiral molecule whose structure is not known, that is, the structure of the molecule is in the positive form or (- The information indicating whether or not the shape is) can be obtained even by using only one pulse.

4A illustrates an amplified ORD signal measured using incident light having a center wavelength of about 400 nm in an optically active device according to one embodiment, and FIG. 4B illustrates a signal-to-noise ratio calculated from the ORD signal shown in FIG. 4A.

Referring to FIG. 4A, the colorless points 301 represent a result of measuring an ORD signal with Ni-(+)-(tartrate) ₂ using an optical activity measuring device according to an embodiment. Points 302 indicate the results of measuring the ORD signal with respect to Ni-(-)-(tartrate) ₂ using the optical activity measuring device according to one embodiment. On the other hand, the x-axis of the graph represents the rotation angle of the polarizer 201. As shown, it can be seen that the smaller the rotation angle is amplified signal measured in proportion thereto. The dotted line between the points 301, 302 represents the theoretical calculation.

Referring to FIG. 4B, the colorless points 303 represent the signal-to-noise ratio calculated from the ORD signal 301 of Ni-(+)-(tartrate) ₂ shown in FIG. 4A. In addition, colored dots 304 represent the signal-to-noise ratio calculated from the ORD signal 302 of Ni-(-)-(tartrate) ₂ shown in FIG. 4A. As shown, it can be seen that the signal-to-noise ratio shown in FIG. 4B also increases as the rotation angle of the polarizer 201 decreases so that the amplification factor of the measurement signal increases. That is, selective amplification and measurement of very small optically active signals is possible.

5 is a graph illustrating a result of measuring a CD signal and an ORD signal for a spiral aggregate using an optical activity measuring apparatus according to an embodiment.

In the measurement result shown in FIG. 5, the result measured using the dye molecule as a sample is shown. The dye molecule has no optical activity in the monomer state, but when a plurality of dye molecules are formed into a spiral aggregate using DNA as a framework, the dye molecule has optical activity due to its overall structure. The graphs 401 and 402 shown in FIG. 5 show the results of measuring the CD signal and the ORD signal with respect to the spiral aggregate of dye molecules, respectively. As shown in the drawing, normal measurements were made on the helical aggregates of the dye molecules, and it can be seen that the optical activity measuring apparatus and method according to one embodiment may be applicable to any environment exhibiting chiral properties.

Although the present invention described above has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and variations may be made therefrom. However, such modifications should be considered to be within the technical protection scope of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (18)

A light source unit irradiating a white light pulse signal;
A polarization controller configured to adjust the polarization of the white light pulse signal to generate incident light including a pump light in a first polarization direction and a reference light in a second polarization direction, and to incident the incident light on a sample having a chiral property;
A polarization beam splitter that separates the incident light passing through the sample into a first component in the first polarization direction and a second component in the second polarization direction; And
A detection unit for measuring the optical activity of the sample using the first component and the second component,
The light source unit includes:
A sample cuvette comprising water; And
And a light source for irradiating the water with a femtosecond laser pulse signal to generate the white light pulse signal.
The method of claim 1,
And said second polarization direction is perpendicular to said first polarization direction.
delete The method of claim 1,
The polarization control unit includes a polarizer having an alignment direction arranged at a predetermined angle with respect to the first polarization direction,
And said incident light has rotated linearly polarized light.
The method of claim 1,
The polarization control unit includes a tension plate to which pressure is applied in a direction inclined with respect to the first polarization direction,
The incident light has an elliptically polarized light having the first polarization direction and the second polarization direction as a major axis direction and a minor axis direction, respectively.
The method of claim 1,
Wherein:
A monochromator optically coupled to the polarizing beam splitter to disperse the first component and the second component according to a wavelength; And
And a charge coupled device detector for receiving the first component and the second component through the monochromator.
The method according to claim 6,
The detector further comprises a neutral filter optically connected between the polarizing beam splitter and the monochromator to reduce the intensity of the first component.
The method according to claim 6,
And the charge coupled device detector comprises a first region for receiving the first component and a second region for receiving the second component and spatially separated from the first region.
The method of claim 1,
And the detection unit measures a circularly polarized dichroic signal or an optical rotation dispersion signal using the first component and the second component.
Irradiating the femtosecond laser pulse signal to water to generate a white light pulse signal;
Adjusting the polarization of the white light pulse signal to generate incident light including pump light in a first polarization direction and reference light in a second polarization direction;
Injecting the incident light into a sample having chiral properties;
Separating the incident light passing through the sample into a first component in the first polarization direction and a second component in the second polarization direction; And
Measuring the optical activity of the sample using the first component and the second component.
The method of claim 10,
And said second polarization direction is perpendicular to said first polarization direction.
The method of claim 10,
And said incident light has linearly polarized light rotated by a predetermined angle with respect to said first polarization direction.
The method of claim 10,
The said incident light has elliptical polarization which makes the said 1st polarization direction and the said 2nd polarization direction into a long axis direction and a short axis direction, respectively, The optical activity measuring method characterized by the above-mentioned.
delete The method of claim 10,
Before the optical activity of the sample is measured, further comprising dispersing the first component and the second component in accordance with the wavelength.
The method of claim 10,
Measuring the optical activity of the sample,
Receiving the first component in a first region of a charge coupled device detector; And
And receiving the second component in a second region different from the first region of the charge coupled device detector.
The method of claim 10,
Measuring the optical activity of the sample,
Measuring a ratio between the intensity of the first component and the intensity of the second component; And
Measuring a circular dichroism signal or an optical rotation dispersion signal using the measured ratio.
18. The method of claim 17,
Before measuring the ratio, further comprising reducing the intensity of the first component.

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