Upright quantum diamond microscope device

Abstract

The present invention relates to an upright quantum diamond microscope device comprising: a nitrogen-vacancy defect diamond substrate which is mounted in a housing and positioned below an objective lens so as to face the objective lens; a bias magnetic field application unit for applying a magnetic field to the nitrogen-vacancy defect diamond substrate; a microwave oscillation unit for applying microwaves to the nitrogen-vacancy defect diamond substrate; a laser light source for irradiating laser light onto the nitrogen-vacancy defect diamond substrate; an imaging unit for detecting, from the nitrogen-vacancy defect diamond substrate, light excited in response to the incident laser light; and a main processing unit for measuring and providing a current signal for an object to be inspected, by using image information captured by the imaging unit.

Description

Established quantum diamond microscope device

[0001] The present invention relates to an upright quantum diamond microscope device, and more particularly, to an upright quantum diamond microscope device capable of performing a diagnosis on a current signal flowing through an inspection object.

[0002] Diamond crystals are composed of carbon atoms, but when a carbon atom is replaced by another type of atom, a stable lattice defect is created. One such defect is a nitrogen-vacancy center, where a carbon atom is replaced by a nitrogen atom, and the neighboring carbon atom is removed, leaving a vacant space.

[0003] A diamond nitrogen-vacancy center (DNV) has an electron spin with a spin number (S) of 1, so the spin quantum can have three spin states (ms): +1, 0, and -1. When there is no external magnetic field along the axis of the nitrogen vacancy in the diamond, the spin quantum of the +1 and -1 spin states (ms) overlap and exist in similar energy levels. In contrast, when an external magnetic field is present along the axis of the nitrogen vacancy in the diamond, the Zeeman effect causes the overlap of the nitrogen-vacancy spin quantum of the +1 and -1 spin states (ms) to disappear, and they exist in different energy levels. As a result, the nitrogen-vacancy spin quantum has two resonance frequencies corresponding to spin transitions between spin states (ms) 0 and spin states (ms) +1 or between spin states (ms) 0 and spin states (ms) -1. The difference between the two resonance frequencies is proportional to the magnitude of the external magnetic field.

[0004] When a diamond nitrogen vacancy is irradiated with a 532 nm wavelength laser, quanta in the spin state (ms) 0 are excited and then return to the ground state while emitting red light of 600 nm or more. In addition, quanta in the spin state (ms) +1 and spin state (ms) -1 are excited and then return to the ground state while changing to the spin state (ms) 0 without emitting red light. Therefore, the amount of fluorescence of the emitted red light can be proportional to the amount of spin quanta in the spin state (ms) 0.

[0005] Applying two resonant frequencies corresponding to spin transitions to the diamond nitrogen vacancy induces spin transitions from spin state (ms) 0 to spin state (ms) +1 or spin state (ms) -1. As a result, the quantum quantity of spin state (ms) 0 decreases, and the amount of red light fluorescence emitted also decreases.

[0006] Therefore, by applying a varying microwave frequency to a diamond nitrogen vacancy and recording the change in fluorescence amount according to the frequency, an optically detected magnetic resonance (ODMR) spectrum can be obtained in the form of a reduced fluorescence amount at the resonance frequency corresponding to each spin transition. Based on the difference between the two resonance frequencies where the fluorescence amount is reduced in this ODMR spectrum, the magnitude of the magnetic field applied to the diamond nitrogen vacancy can be determined.

[0007] Diamond nitrogen-vacancy sensors are highly sensitive to temperature and magnetic fields, and are actively used to measure the fine spatial distribution of temperature or magnetic fields. As an example, a temperature measuring device utilizing diamond nitrogen vacancy defects is disclosed in Korean Patent Publication No. 10-2018-0104471.

[0008] Meanwhile, various attempts are being made to utilize diamond monds with nitrogen vacancy defects, and a device that supports the measurement of information related to electric or magnetic fields of an inspection target in an upright state while being applied to a quantum microscope is required.

[0009] The present invention was created to solve the above-mentioned requirements, and the purpose of the present invention is to provide an upright quantum diamond microscope device that can collect an image of a current flowing in a conductor of an integrated circuit, a display, a secondary battery, etc., and detect the presence or absence of defects such as overcurrent, short circuit, and open circuit using an upright quantum diamond microscope.

[0010] In order to achieve the above object, the upright quantum diamond microscope device according to the present invention comprises: a housing having an objective lens mounted thereon; a nitrogen vacancy defect diamond substrate mounted in the housing so as to face the objective lens from below the objective lens; a bias magnetic field applying unit installed in the housing to apply a magnetic field to the nitrogen vacancy defect diamond substrate; a microwave oscillation unit to apply microwaves to the nitrogen vacancy defect diamond substrate; a laser light source installed in the housing to irradiate laser light to the nitrogen vacancy defect diamond substrate; an imaging unit for detecting excitation light excited in response to the laser light incident from the nitrogen vacancy defect diamond substrate in response to a current flowing in an inspection target disposed below the nitrogen vacancy defect diamond substrate; and a main processing unit for measuring and providing a current signal for the inspection target using image information captured by the imaging unit.

[0011] Preferably, the laser light source is applied to emit light with a wavelength of 530 to 540 nm.

[0012] According to one aspect of the present invention, the imaging unit comprises a CCD camera that generates image information for excitation light incident through the objective lens and provides the image information to the main processing unit; a main filter that transmits the excitation light between the objective lens and the CCD camera and blocks light outside the wavelength band of the excitation light; a dichroic mirror that is arranged between the main filter and the objective lens and reflects white light to propagate to the objective lens and transmits the excitation light to propagate along an optical path leading to the CCD camera; and an auxiliary light source that emits white light to the dichroic mirror.

[0013] In addition, the microwave oscillation unit may be constructed with a conductive antenna formed in an omega shape and disposed on the nitrogen vacancy defect diamond substrate, and an MW oscillator that generates microwaves from the conductive antenna by applying an oscillation signal through the conductive antenna.

[0014] In addition, the MW oscillator is constructed so that it can be controlled by the main processing unit and output by varying the frequency of the microwave output through the conductive antenna.

[0015] In addition, a power control filter may be further provided, which is positioned opposite to the light emission direction of the laser light source so as to control the power of light emitted from the laser light source.

[0016] According to the upright quantum diamond microscope device of the present invention, an advantage is provided in that an image of a current flowing in a conductor of an integrated circuit, a display, a secondary battery, etc. can be collected using an upright quantum diamond microscope, and the presence or absence of defects such as overcurrent, short circuit, and open circuit can be detected.

[0017] Figure 1 is a schematic drawing of an upright quantum diamond microscope device according to the present invention.

[0018] Figure 2 is a drawing for explaining a structure for generating microwaves in the nitrogen vacancy defect diamond substrate of Figure 1.

[0019] Figure 3 is a drawing showing another example of an optical alignment structure to explain the excitation light collection process of the upright quantum diamond microscope device of Figure 1.

[0020] Figure 4 is a schematic drawing illustrating the structure of the nitrogen vacancy defect diamond substrate of Figure 1.

[0021] FIG. 5 is a diagram schematically showing the generation of an Oersted magnetic field when current flows through a test object facing the nitrogen vacancy defect diamond substrate of FIG. 1.

[0022] Hereinafter, an upright quantum diamond microscope device according to a preferred embodiment of the present invention will be described in more detail with reference to the attached drawings.

[0023] FIG. 1 is a schematic drawing of an upright quantum diamond microscope device according to the present invention.

[0024] Referring to FIG. 1, an upright quantum diamond microscope device (100) according to the present invention comprises a housing (120), a nitrogen vacancy defect diamond substrate (150), a bias magnetic field applying unit (160), a microwave oscillation unit (170), a laser light source (180), a displacement sensor (184), a sub-dichroic mirror (186), an imaging unit (190), and a main processing unit (200).

[0025] The housing (120) is an element forming the microscope body (110) including the objective lens (141) and is constructed so that related elements can be mounted from the nitrogen vacancy defect diamond substrate (150) to the imaging unit (190).

[0026] The moving stage (130) is placed under the nitrogen vacancy defect diamond substrate (150) and is installed movably with respect to the housing (120) to provide a mounting area where the inspection target (10) can be mounted.

[0027] These housings (120) and moving stages (130) form the microscope body (110).

[0028] A nitrogen vacancy defect diamond substrate (150) is mounted in the housing (120) facing the objective lens (141) at the bottom of the objective lens (141).

[0029] The nitrogen vacancy defect diamond substrate (150) is formed with atomic-sized point defects consisting of nitrogen atoms replacing carbon atoms in the crystal lattice within the diamond crystal and vacancies in which adjacent lattice points are vacancies.

[0030] The nitrogen vacancy defect diamond substrate (150) functions as an NV diamond sensor with a long spin coherence time, and emits a broad photoluminescence (PL) excitation light of 630 to 850 nm when excited by laser light.

[0031] A bias magnetic field applying unit (160) is installed in the housing (120) and applies a bias magnetic field to the nitrogen vacancy defective diamond substrate (150). The bias magnetic field applying unit (160) is constructed with a magnetic field applying module (163) that is arranged around the nitrogen vacancy defective diamond substrate (150) to apply a magnetic field to the nitrogen vacancy defective diamond substrate (150), and a magnetic field forming unit (165) that drives the magnetic field applying module (163) to form a magnetic field. Alternatively, the bias magnetic field applying unit (160) may be constructed with a structure in which a permanent magnet is applied to the position where the magnetic field applying module (163) is arranged and the magnetic field forming unit (165) is omitted.

[0032] The bias magnetic field application unit (160) is applied to secure initial information on defects in the nitrogen vacancy defect diamond substrate (150).

[0033] That is, the bias magnetic field applying unit (160) applies a constant external magnetic field to the nitrogen vacancy defect diamond substrate (150) to separate the electron spins of the nitrogen vacancy defect diamond substrate (150).

[0034] The microwave generator (170) applies microwaves to a nitrogen vacancy defect diamond substrate (150), and is described with reference to FIG. 2.

[0035] The microwave oscillation unit (170) is configured to generate microwaves through a conductive antenna (173) formed on a printed circuit board (175) positioned oppositely on a nitrogen vacancy defect diamond substrate (150).

[0036] The challenge antenna (173) is placed on top of a nitrogen vacancy defect diamond substrate (150) and is formed in an omega shape.

[0037] That is, the challenge antenna (173) has an omega (Ω) shape that surrounds a through hole that penetrates the center of the printed circuit board (175) vertically and has a portion extending in a straight line from both ends of a partially open C-shaped annular portion, and is formed on the printed circuit board (175) using a conductive material.

[0038] A microwave (MW) generator (177) applies an oscillation signal through a conductive antenna (173) to generate microwaves from the conductive antenna (173).

[0039] This challenge antenna (173) can be constructed to be connected to a MW oscillator (177) via a coaxial cable (174) and generate microwaves corresponding to an applied oscillation signal.

[0040] In addition, the microwave (MW) generator (177) is controlled by the main processing unit (200) so that the frequency of the microwave output through the conductive antenna (173) can be varied and output.

[0041] A laser light source (180) is installed in the housing (120) and irradiates laser light onto a nitrogen vacancy defect diamond substrate (150).

[0042] The laser light source (180) is applied to emit light with a wavelength of 530 to 540 nm. As an example, the laser light source (180) is applied to emit light with a wavelength of 532 nm.

[0043] The power control filter (182) is positioned opposite to the light emission direction of the laser light source (180) so as to control the power of light emitted from the laser light source (180).

[0044] The displacement sensor (184) is applied to measure the distance between the nitrogen vacancy defect diamond substrate (150) and the inspection target (10).

[0045] The displacement sensor (184) can be constructed with a displacement measurement light source (184a) that emits 1064 nm infrared laser light and a photodetector (184b) that receives 1064 nm reflected light incident in reverse from a sub dichroic mirror (186).

[0046] The sub-dichroic mirror (186) is constructed to reflect 1064 nm light emitted from the displacement measuring light source (184a) of the displacement sensor (184) or 1064 nm reflected light reflected from the nitrogen vacancy defect diamond substrate (150) and the inspection target (10) in a direction perpendicular to the incident path, and to transmit light outside of 1064 nm.

[0047] In this case, the displacement measurement light source (184a) of the displacement sensor (184) is driven in the main processing unit (200) described later, and then the main processing unit (200) calculates the distance between the nitrogen vacancy defect diamond substrate (150) and the inspection target (10) from the parallax between the light reflected from the nitrogen vacancy defect diamond substrate (150) and the light reflected from the upper surface of the inspection target (10) among the light received from the photodetector (184b).

[0048] In contrast, when the distance between the nitrogen vacancy defect diamond substrate (150) and the inspection target (10) is adjusted to have a set reference distance value, the displacement sensor (184) and the sub-dichroic mirror (186) may be omitted.

[0049] The imaging unit (190) detects the excited light corresponding to the laser light emitted from the laser light source (180) and incident on the nitrogen vacancy defective diamond substrate (150) in response to the current flowing in the inspection target (10) placed under the nitrogen vacancy defective diamond substrate (150).

[0050] The imaging unit (190) is equipped with a CCD camera (192), a main filter (194), a dichroic mirror (195), and an auxiliary light source (196).

[0051] The CCD camera (192) generates image information on the excited light incident from the objective lens (141) through the main filter (194) and provides it to the main processing unit (200). That is, the CCD camera (192) collects and processes a luminescent image of the nitrogen vacancy defect diamond substrate (150) through the excited light emitted from the nitrogen vacancy defect diamond substrate (150).

[0052] The main filter (194) is placed between the objective lens (141) and the CCD camera (192) to transmit the excitation light and block the transmission of light outside the wavelength band of the excitation light.

[0053] That is, the main filter (194) blocks the 532 nm laser light emitted from the laser light source (180) and transmits only the excitation light emitted from the nitrogen vacancy defect diamond substrate (150).

[0054] The main filter (194) can be structured to transmit only light with a wavelength of 550 nm or more.

[0055] Reference numeral 197 is an eyepiece installed between the main filter (194) and the CCD camera (192).

[0056] A dichroic mirror (195) is placed between the main filter (194) and the objective lens (141), reflecting white light incident from an auxiliary light source (196) and passing it to the objective lens (141), and transmitting the excitation light so that it passes through the optical path leading to the CCD camera (192).

[0057] The auxiliary light source (196) emits white light to the dichroic mirror (195). The auxiliary light source (196) is applied to irradiate light onto the nitrogen vacancy defect diamond substrate (150) to obtain an image image, and may be omitted.

[0058] Meanwhile, it goes without saying that the optical path from the objective lens (141) to the CCD camera (192) can be constructed with a structure in which a mirror (145) as shown in FIG. 3 is applied to convert the optical path as needed.

[0059] The main processing unit (200) controls the MW generator (177) to vary the frequency of the microwave, and measures the current signal for the inspection target (10) using the image information captured by the CCD camera (192) of the imaging unit (190) and provides it to the display unit (210).

[0060] The main processing unit (200) processes and provides the magnetic field and current density distribution of the inspection target (10) so that they can be visualized through the quantum spin state principle of the nitrogen vacancy defect diamond substrate (150).

[0061] The main processing unit (200) collects luminescence signals for each pixel from a CCD camera (192), and calculates the desired parameters based on the collected luminescence signals using an optical-magnetic field and optical-induced magnetic field-current density conversion algorithm.

[0062] The parameters calculated for the inspection object (10) by the main processing unit (200) may be applied as magnetic field strength or current density.

[0063] As an example in the case of magnetic field strength, first, a 2.87 GHz microwave (MW; Microwave) signal is applied through the MW oscillator (170) to resonate the spin ground state of the nitrogen vacancy defect diamond substrate (150) (m s =0→m s =±1 @ground state). Next, the laser light is emitted from the laser light source (180), and the electrons (m) are excited by the excitation of the incident laser light. s =±1 @excited state) non-radiative transition probability increase (m) s =±1 @ground state→meta state) causes luminescence loss only at 2.87 GHz, resulting in a change in the ground spin state (m s =±1 @ground state) is optically distinguished, and the spin state is separated by an external magnetic field (m s =+1 & m s =-1 at ground state) and extract the magnetic field strength through optical measurement of the separated energy difference.

[0064] Below, the process of measuring the current density corresponding to the current flowing in the wire of the inspection target (10) under the control of the main processing unit (200) is described.

[0065] First, the vector magnetic field (B) for the four directions (A, B, C, D) of the nitrogen vacancy defect diamond substrate (150) shown in Figure 4 when the current of the inspection object (10) is turned on and off can be expressed by the following mathematical expressions 1 and 2.

[0066]

[0067]

[0068] Here, i=A, B, C, D, and f is the electron spin resonance frequency of the nitrogen vacancy defect diamond substrate (150). is the electron gyromagnetic ratio (28.0249 GHz / T) and is a constant value.

[0069] Next, the magnetic field difference of the nitrogen vacancy defect diamond substrate (150) in four directions is extracted using the following mathematical expression 3.

[0070]

[0071] Afterwards, coordinate transformation is performed in the NV (nitrogen vacancy) direction to the x, y, z coordinate system using the mathematical formula 4 below.

[0072]

[0073] Here, is a unit vector and can be expressed by mathematical equations 5 to 8 below.

[0074]

[0075]

[0076]

[0077]

[0078] Afterwards, the Oersted field induced by the current flowing in the test object (10) is expressed as shown in Fig. 5 through the Biot-Savart law relationship. ) is defined by the mathematical expression 9 below.

[0079]

[0080] Here, μ0 is the permeability in air, r is the position of the diamond substrate (150), r' is the position of the inspection object (10), and J is the current density. d 3 is a symbol representing triple integral.

[0081] Therefore, the Oersted field can be defined in real space in the direction of each vector by the following mathematical equations 10 to 12.

[0082]

[0083]

[0084]

[0085] Also, the distance Z between the current source and the NV (nitrogen vacancy) electron spin P In the magnetic field ( ) can be measured to obtain the two-dimensional (2D) current density J(x,y), and the 2D Fourier transform of the magnetic field and current density in the reciprocal space is defined by the following mathematical equations 13 and 14.

[0086]

[0087] Here, kx, ky are the spatial frequencies of each coordinate axis, and bk is the magnetic field in the reciprocal lattice space.

[0088]

[0089] In addition, by applying Equations 13 and 14 to Equations 10, 11, and 12, the magnetic field in the reciprocal lattice space can be expressed as Equations 15 to 17 below.

[0090]

[0091]

[0092]

[0093] Next, under the assumption of static current, the current density is given by the continuity equation ( ) and must satisfy the condition of mathematical expression 18 below in the reciprocal lattice space.

[0094]

[0095] Additionally, the current density in real space is defined by the following mathematical equation 19 through the inverse Fourier transform.

[0096]

[0097] Therefore, the amplitude of the two-dimensional current density is calculated using the mathematical expression 20 below.

[0098]

[0099] Meanwhile, this established quantum diamond microscope device (100) can be used to collect images of current flowing in conductors of semiconductor integrated circuits, batteries, conductors, secondary batteries, etc., and to detect the presence or absence of defects such as overcurrent, short circuit, and opening. In addition, this device can also be used for material inspection by obtaining magnetic field information of magnetic substances (geological / mineral substances, superconductors, nanomaterials, etc.), magnetoencephalography measurement, and virus or bacteria detection.

[0100] According to the upright quantum diamond microscope device described above, it provides the advantage of being able to collect images of current flowing in conductors of integrated circuits, displays, secondary batteries, etc. using an upright quantum diamond microscope and to detect the presence or absence of defects such as overcurrent, short circuit, and open circuit.

Claims

1. A housing with an objective lens; A nitrogen-vacuum-defective diamond substrate mounted on the housing so as to face the objective lens at the lower portion of the objective lens; A bias magnetic field applying unit installed in the housing and applying a magnetic field to the nitrogen vacancy defect diamond substrate; A microwave generator for applying microwaves to the above nitrogen vacancy defect diamond substrate; A laser light source installed in the housing and irradiating laser light onto the nitrogen vacancy defect diamond substrate; An imaging unit that detects excitation light generated in response to the laser light incident from the nitrogen vacancy defective diamond substrate in response to a current flowing through a test object placed under the nitrogen vacancy defective diamond substrate; An upright quantum diamond microscope device characterized by comprising a main processing unit that measures and provides a current signal for the inspection target using image information captured by the above-described capturing unit.

2. An upright quantum diamond microscope device, characterized in that the laser light source in the first paragraph emits light having a wavelength of 530 to 540 nm.

3. In the first paragraph, the imaging unit A CCD camera that generates image information on the excited light incident through the objective lens and provides the image information to the main processing unit; A main filter that transmits the excitation light between the objective lens and the CCD camera and blocks light outside the wavelength band of the excitation light; A dichroic mirror arranged between the main filter and the objective lens to reflect white light and transmit it to the objective lens, and transmit the excitation light to the optical path leading to the CCD camera; An upright quantum diamond microscope device characterized by comprising an auxiliary light source that emits white light to the above dichroic mirror.

4. In the third paragraph, the microwave oscillation unit An upright quantum diamond microscope device characterized by comprising: a conductive antenna formed in an omega shape and disposed on the upper portion of the nitrogen vacancy defect diamond substrate; and a MW oscillator that generates microwaves from the conductive antenna by applying an oscillation signal through the conductive antenna.

5. In the fourth paragraph, the MW oscillator is controlled by the main processing unit so as to output a variable frequency of microwaves output through the conductive antenna. A quantum diamond microscope device.

6. An upright quantum diamond microscope device characterized in that, in the fifth paragraph, it further comprises a power control filter arranged opposite to the light emission direction of the laser light source so as to control the power of light emitted from the laser light source.

Images