TUNING-FORK BASED NEAR FIELD PROBE FOR SPECTRAL MEASUREMENT, NEAR-FIELD MICROSCOPE USING THE SAME, AND SPECTRAL ANALYSIS METHOD USING NEAR-FIELD MICROSCOPE
First Claim
1. A tuning-fork based near-field probe for spectral measurement, comprising:
- a first electrode and a second electrode arranged apart from each other; and
a wire-shaped nano-probe downward attached to a one-side end of the second electrode and configured to vibrate in a perpendicular direction with respect to a sample,wherein the nano-probe comprises;
a shaft for receiving a terahertz pulse incidented through a means for focusing light;
an end part for localizing the receive terahertz pulse to interact with the sample, and scattering a terahertz pulse, into air, which has obtained local information of the sample in the localizing procedure; and
a tapered region for connecting the shaft and the end part, wherein the length of the nano-probe, which is defined as a sum of the length of the shaft and the length of the tapered region is formed to be longer than the radius of a focus of a beam by the terahertz pulse which is focused by the means for focusing light.
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Accused Products
Abstract
The present invention is provided to remove scattering from other parts, except for an end part of a nano-probe, in a near-field microscope, and to enable a spectral analysis by delaying the generation of multiple reflections caused through the shaft of the nano-probe. A first characteristic of the present invention is to temporally delay generation of multiple reflections by manufacturing a probe portion to have a predetermined length or more in a tuning-fork based near-field probe. A second characteristic of the present invention is to provide a near-field microscope which includes a tuning-fork based near-field probe having a structure as above, and can measure a time-domain transient reaction of a scattered wave. A third characteristic of the present invention is to provide a method for performing a spectral analysis on a time-domain signal measured by the near-field microscope.
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Citations
21 Claims
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1. A tuning-fork based near-field probe for spectral measurement, comprising:
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a first electrode and a second electrode arranged apart from each other; and a wire-shaped nano-probe downward attached to a one-side end of the second electrode and configured to vibrate in a perpendicular direction with respect to a sample, wherein the nano-probe comprises; a shaft for receiving a terahertz pulse incidented through a means for focusing light; an end part for localizing the receive terahertz pulse to interact with the sample, and scattering a terahertz pulse, into air, which has obtained local information of the sample in the localizing procedure; and a tapered region for connecting the shaft and the end part, wherein the length of the nano-probe, which is defined as a sum of the length of the shaft and the length of the tapered region is formed to be longer than the radius of a focus of a beam by the terahertz pulse which is focused by the means for focusing light. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A near-field microscope using a tuning-fork based near-field probe for spectral measurement, the near-field probe microscope comprising:
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an optical system configured to include a plurality of beam splitters, a mirror, and a lens for transferring a laser pulse generated by a fast-pulse laser to a terahertz pulse generation device, and to include one or more beam splitters and a plurality of mirrors for transferring a part of the laser pulse generated by the fast-pulse laser to an electric field detector; a sample stand configured to enable a location and a height thereof to be controlled; a plurality of first optical components for transferring and focusing a terahertz pulse generated by the terahertz pulse generation device on a sample; a tuning-fork based near-field probe comprising a first electrode and a second electrode arranged apart from each other, and a wire-shaped nano-probe downward attached to a one-side end of the second electrode and configured to vibrate in a perpendicular direction with respect to the sample, wherein the nano-probe includes a shaft for receiving a terahertz pulse focused through the first optical components, an end part for allowing the focused terahertz pulse to interact with the sample and scattering a terahertz pulse, into air, which has been subjected to an interaction procedure, and a tapered region for connecting the shaft and the end part; an AC voltage generation device connected to the first and second electrodes of the near-field probe in order to vibrate the near-field probe; an electric field detector for measuring an alternating current flowing through the tuning-fork based near-field probe; a control device for controlling a height of the sample stand to uniformly maintain a distance between the end part of the near-field probe and the sample; a plurality of second optical components for focusing a terahertz pulse directly reflected from the sample and a part of a pulse scattered from the end part of the near-field probe onto the surface of the electric field detector; a lock-in amplifier for demodulating a signal detected through the electric field detector with a vibration frequency of the nano-probe or harmonic of the nano-probe, thereby extracting a component modulated by vibration of the nano-probe; a mechanical optical delay unit for measuring a transient reaction of the terahertz pulse in a time domain; and a control photoconductive (control PC) for analyzing the measured transient reaction in a frequency domain, and measuring a characteristic spectrum of the sample, wherein the length of the nano-probe, which is a sum of the lengths of the shaft and the tapered region is longer than the radius of a focus of a terahertz beam focused by a means for focusing light. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A spectral analysis method using a near-field microscope, the method comprising the steps of:
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(a) transferring an ultrafast laser pulse generated by a fast-pulse laser to a terahertz generation unit using a plurality of beam splitters, a mechanical chopper, a mechanical optical delay unit, and a mirror; (b) transferring and focusing a terahertz pulse generated by the terahertz generation device onto a sample attached on a piezo-stage; (c) mounting a tuning-fork based near-field probe above the sample and driving the near-field probe, the near-field probe comprising;
a wire-shaped nano-probe downward attached to a one-side end of a second electrode of first and second electrodes arranged apart from each other, and configured to vibrate in a perpendicular direction with respect to the sample; and
a wire-shaped knife edge attached to a one-side end of the first electrode to stabilize vibration of the nano-probe;(d) measuring, through an electric field detector, an electric field of a pulse wave scattered from an end part of the near-field probe and a terahertz pulse directly reflected from the sample; (e) demodulating a signal, which is detected through the electric field detector, with a vibration frequency of the nano-probe or a harmonic of the nano-probe through a lock-in amplifier, thereby extracting only a scattered wave of the nano-probe; and (f) recoding a harmonic component detected through the lock-in amplifier while scanning a mechanical delay line, acquiring a time-domain signal, Fourier-transforming the acquired time-domain signal, and performing an analysis in a frequency domain, wherein characteristics of the sample are measured by removing second and third pulse waves by multiple reflections, performing a Fourier transform, and performing an analysis in a frequency domain.
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Specification