CN208588756U - A kind of Kerr effect measuring device - Google Patents

Abstract

The utility model relates to the electromagnetic detection fields of optical technology measurement, a kind of Kerr effect measuring device, including laser I, polarizer, convex lens I, lens platform, atomic force microscope, probe, sample, sample stage, magnet, signal generator, oscillograph, convex lens II, light ball modulator, half-wave plate I, chopper, laser II, convex lens III, filter plate, half-wave plate II, analyzer, photodetector, lock-in amplifier I, lock-in amplifier II, computer, input path I, input path II, there is in zx plane through-hole I in probe, through-hole II and through-hole III, the axis of through-hole II is along the rotary table axis direction, the axis of through-hole I and through-hole III are located at the two sides of the through-hole II axis, and with the through-hole II axis at 45 degree of angles, The utility model can measure single nanostructure, and the spatial resolution of sub-micrometer scale can be reached to the dynamic measurement of the magnetization of sample surfaces, background signal is reduced, increases sensitivity.

Description

A kind of Kerr effect measuring device

Technical field

The utility model relates to a kind of electromagnetic detections of optical technology fields of measurement, especially a kind of based on pumping one A kind of Kerr effect measuring device of detection method.

Background technique

Kerr magnetooptical effect measuring device is one of material surface magnetism research important means, its working principle is that base Kerr magnetooptical effect caused by interaction, can not only carry out monoatomic layer thickness material between Yu Youguang and magnetized medium Magnetic detection, and can realize non-contact measurement, the magnetic order of magnetic ultrathin film, magnetic anisotropy, layer coupling and There is important application in the research of the transformation behavior of magnetic ultrathin film etc..Kerr magnetooptical effect measuring device mainly passes through Detect the magnetization that light intensity variation caused by the polarization state after a branch of linearly polarized light reflects on the surface of the material changes carries out sample surfaces Observation.Prior art defect is: in the prior art, time-resolved Ke Er signal is obtained using pumping-detection method In experiment, change the polarization state of pump light usually using light ball modulator, still, light ball modulator can issue and its work The electromagnetic radiation of same frequency, therefore the equipment such as diode laser near it are interfered vulnerable to electromagnetic coupling, especially It is the coupling on detection light, will lead to the generation of background signal, and the drift of this background signal will limit detectable signal Sensitivity, a kind of Kerr effect measuring device can solve problem.

Utility model content

To solve the above-mentioned problems, the utility model obtains nanoscale sample surfaces using high-precision positioning device Magnetization information Kerr magnetooptical effect measurement can be carried out to single nanostructure using special atomic force microscope probe. In addition, carry out time-resolved Ke Er signal measurement using pumping-detection method, by being modulated to pump light and special Phase-sensitive detection method reduces electromagnetic radiation that light ball modulator issues to the electromagnetism coupling of the equipment such as diode laser near it Interference is closed, background signal is reduced, increases the sensitivity of detectable signal.

The technical scheme adopted by the utility model is

A kind of Kerr effect measuring device mainly includes laser I, polarizer, convex lens I, lens platform, atomic force Microscope, sample, sample stage, magnet, signal generator, oscillograph, convex lens II, light ball modulator, half-wave plate I, is cut probe Wave device, laser II, convex lens III, filter plate, half-wave plate II, analyzer, photodetector, lock-in amplifier I, locking phase are put Device II, computer, input path I, input path II, the probe are atomic force microscope probe and are truncated conical shape greatly, institute Rotary table axis direction and horizontal plane are stated, the upper bottom surface diameter of the rotary table is 3 microns, bottom surface diameter is 1.5 microns, institute The axis in probe with through-hole I, through-hole II and through-hole III, the through-hole II in zx plane is stated along the rotary table axis side To, the axis of the through-hole I and through-hole III be located at the two sides of the through-hole II axis and with the through-hole II axis At 45 degree of angles, probe is located at atomic force microscope lower end, and sample is located on sample stage, the sample, sample stage, magnet successively position Immediately below the probe, the laser beam of the laser I transmitting successively through polarizer, convex lens I, lens platform, atomic force microscope, Probe, to form input path I, the laser beam of the laser II transmitting successively chopped device, half-wave plate I, photoelastic modulation Device, convex lens II, lens platform, atomic force microscope, probe, to form input path II, laser I is with laser II Titanium-doped sapphire diode laser, the laser that laser I is issued are detection light, and the laser that laser II is issued is pump light, Laser I and laser II is both connected to computer, and the pulse delay lockable between the detection light and pump light is simultaneously adjusted, The detection light that laser I is issued can be successively through polarizer, convex lens I, lens platform, atomic force microscope, through-hole I, and irradiates Onto sample, the light reflected from sample being capable of successively via through holes III, atomic force microscope, lens platform, convex lens III, filtering Piece, half-wave plate II, analyzer, and enter photodetector, the pump light that laser II is issued being capable of successively chopped device, half-wave Piece I, light ball modulator, convex lens II, lens platform, atomic force microscope, through-hole II, and be irradiated on sample, photodetector Output end connects the input terminal of lock-in amplifier I, the input terminal of the output end connection lock-in amplifier II of lock-in amplifier I, lock The output end of phase amplifier II connects computer, the reference signal frequency of lock-in amplifier I and the modulated signal of light ball modulator Frequency is identical, and the reference signal frequency of lock-in amplifier II and the frequency of chopper are identical, through-hole I, through-hole in the probe The diameter of II and through-hole III are 200 nanometers, and half-wave plate II and half-wave plate I can be rotated by axis of optical path.

The step of being measured using a kind of Kerr effect measuring device are as follows:

One, makes probe approach sample surfaces by atomic force microscope, and probe is enabled to scan in two micron ranges, scanning Speed 2nm/s determines sample edge position by sample surface profiles obtained in scanning；

Two, probes bounce back upwards, and retraction distance is 50 nanometers, and close the scanning feedback of atomic force microscope；

Three, adjust the position of laser I, so that the laser beam that laser I is issued is able to enter through-hole I；Adjust laser The position of II, so that the laser beam that laser II is issued is able to enter through-hole II；

It is 20Hz that chopper chopping frequency, which is arranged, in four,；

The modulating frequency that light ball modulator is arranged in five, is 50kHz；

Six, laser II issue pump light, and the pump light being capable of chopped device, half-wave plate I, light ball modulator, convex lens Mirror II, lens platform, atomic force microscope, through-hole II, and be irradiated on sample, the pump wavelength is 700 nanometers；

Seven, light ball modulators make the polarization state of the pump light with frequency 50kHz left-handed and right-hand circular polarization state it Between change, then the spin direction in sample with pump light polarization state change and change；

Eight, laser I issue detection light, and the detection light can be successively through polarizer, convex lens I, lens platform, atomic force Microscope, through-hole I, and be irradiated on sample, the light reflected from sample being capable of successively via through holes III, atomic force microscope, lens Platform, convex lens III, filter plate, half-wave plate II, analyzer, and enter photodetector；

Nine, rotatable halfwave plate II, so that it is I that the light intensity that photodetector detects, which reaches maximum value,；

Ten, adjust analyzer, so that transmissivity of the detection light of the s polarization state reflected from sample surfaces in analyzer reaches To minimum value；

11, rotatable halfwave plate II, rotation angle is 15 degree, so that there is the detection luminous energy of sufficient intensity by photodetection Device detects；

The signal strength v=I θ that 12, photodetectors detect_kSin (2 Δ), wherein Δ is that the polarization of detection light is flat The deviation angle in face, θ_KFor kerr rotation；

13, photodetector output signals are to lock-in amplifier I, lock-in amplifier I output signal To lock-in amplifier II, lock-in amplifier II output signalTo computer, and thus calculate Kerr rotation θ_K。

The beneficial effects of the utility model are:

The utility model can measure single nanostructure, and the magnetization of sample surfaces is dynamically measured and can be reached The spatial resolution of sub-micrometer scale.In addition, in the experiment of time-resolved Ke Er signal, by being modulated to pump light And special phase-sensitive detection method, electromagnetic radiation that light ball modulator issues is reduced to equipment such as diode lasers near it Electromagnetic coupling interference, reduce background signal, increase the sensitivity of detectable signal.

Detailed description of the invention

It is further illustrated below with reference to the figure of the utility model:

Fig. 1 is utility model diagram.

In figure, 1. laser I, 2. polarizers, 3. convex lens I, 4. lens platforms, 5. atomic force microscope, 6. probes, 7. samples Product, 8. sample stages, 9. magnet, 10. signal generators, 11. oscillographs, 12. convex lens II, 13. light ball modulators, 14. half-waves Piece I, 15. choppers, 16. laser II, 17. convex lens III, 18. filter plates, 19. half-wave plate II, 20. analyzers, 21. light Electric explorer, 22. lock-in amplifier I, 23. lock-in amplifier II, 24. computers.

Specific embodiment

If Fig. 1 is utility model diagram, the lower left corner has an xyz three-dimensional mark, xyz be rectangular coordinate system in space, X/y plane is horizontal plane, zx plane and horizontal plane, a kind of Kerr effect measuring device mainly include laser I 1, Polarizer 2, convex lens I 3, lens platform 4, atomic force microscope 5, probe 6, sample 7, sample stage 8, magnet 9, signal generator 10, oscillograph 11, convex lens II 12, light ball modulator 13, half-wave plate I 14, chopper 15, laser II 16, convex lens III17, filter plate 18, half-wave plate II 19, analyzer 20, photodetector 21, lock-in amplifier I 22, lock-in amplifier II 23, computer 24, input path I, input path II, the probe 6 is atomic force microscope probe and is truncated conical shape, described Rotary table axis direction and horizontal plane, the upper bottom surface diameter of the rotary table is 3 microns, bottom surface diameter is 1.5 microns, described Axis in probe 6 with through-hole I, through-hole II and through-hole III, the through-hole II in zx plane is along the rotary table axis side To, the axis of the through-hole I and through-hole III be located at the two sides of the through-hole II axis and with the through-hole II axis At 45 degree of angles, probe 6 is located at 5 lower end of atomic force microscope, and sample 7 is located on sample stage 8, the sample 7, sample stage 8, magnet 9 are sequentially located at immediately below probe 6, and the laser beam that the laser I 1 emits is successively through polarizer 2, convex lens I 3, lens platform 4, atomic force microscope 5, probe 6, to form input path I, the laser beam of the laser II16 transmitting is successively chopped Device 15, half-wave plate I 14, light ball modulator 13, convex lens II 12, lens platform 4, atomic force microscope 5, probe 6, to be formed Input path II, laser I 1 and laser II 16 are titanium-doped sapphire diode laser, and what laser I 1 was issued swashs Light is detection light, and the laser that laser II 16 is issued is pump light, and laser I 1 is both connected to calculate with laser II 16 Machine, the pulse delay lockable detected between light and pump light are simultaneously adjusted, and the detection light that laser I 1 is issued can be successively It through polarizer 2, convex lens I 3, lens platform 4, atomic force microscope 5, through-hole I, and is irradiated on sample 7, is reflected from sample Light can successively via through holes III, atomic force microscope 5, lens platform 4, convex lens III 17, filter plate 18, half-wave plate II 19, Analyzer 20, and enter photodetector 21, the pump light that laser II 16 is issued being capable of successively chopped device 15, half-wave plate I 14, light ball modulator 13, convex lens II 12, lens platform 4, atomic force microscope 5, through-hole II, and be irradiated on sample, photoelectricity 21 output end of detector connects the input terminal of lock-in amplifier I 22, and the output end of lock-in amplifier I 22 connects lock-in amplifier The input terminal of II 23, the output end of lock-in amplifier II 23 connect computer 24, the reference signal frequency of lock-in amplifier I 22 Rate is identical as the frequency modulating signal of light ball modulator 13, reference signal frequency and the chopper 15 of lock-in amplifier II 23 Frequency is identical, and the diameter of through-hole I, through-hole II and through-hole III in the probe 6 are 200 nanometers, half-wave plate II 19 and half Wave plate I 14 can be rotated by axis of optical path.

The utility model obtains the magnetization information of nanoscale sample surfaces using high-precision positioning device, is used for magnetic The probe of light Ke Er signal measurement has through-hole, can measure to single nanostructure.In addition, in time-resolved Ke Er In the experiment of signal, by being modulated to pump light and special phase-sensitive detection method, the electricity that light ball modulator issues is reduced Magnetic radiation interferes the electromagnetic coupling of the equipment such as diode laser near it, reduces background signal, increases detectable signal Sensitivity.

Claims (2)

1. a kind of Kerr effect measuring device mainly includes laser I, polarizer, convex lens I, lens platform, atomic force microscopy Mirror, probe, sample, sample stage, magnet, signal generator, oscillograph, convex lens II, light ball modulator, half-wave plate I, copped wave Device, laser II, convex lens III, filter plate, half-wave plate II, analyzer, photodetector, lock-in amplifier I, locking phase amplification Device II, computer, input path I, input path II, xyz are rectangular coordinate system in space, x/y plane is horizontal plane, zx plane with Horizontal plane, the probe are atomic force microscope probe and are truncated conical shape, and the rotary table axis direction and horizontal plane hang down Directly, the upper bottom surface diameter of the rotary table is 3 microns, bottom surface diameter is 1.5 microns, is had in zx plane in the probe logical The axis of hole I, through-hole II and through-hole III, the through-hole II are along the rotary table axis direction, the axis of the through-hole I and through-hole III Line is located at the two sides of the through-hole II axis and with the through-hole II axis at 45 degree of angle, and probe is aobvious positioned at atomic force Micro mirror lower end, sample are located on sample stage, and the sample, sample stage, magnet are sequentially located at immediately below probe, the laser I The laser beam of transmitting is successively through polarizer, convex lens I, lens platform, atomic force microscope, probe, so that input path I is formed, The laser beam of laser II transmitting successively chopped device, half-wave plate I, light ball modulator, convex lens II, lens platform, atom Force microscope, probe, so that input path II is formed,

It is characterized in that: laser I and laser II are titanium-doped sapphire diode laser, the laser that laser I is issued is Light is detected, the laser that laser II is issued is pump light, and laser I and laser II are both connected to computer, the detection light Pulse delay lockable between pump light is simultaneously adjusted, and the detection light that laser I is issued can be successively through polarizer, convex lens I, lens platform, atomic force microscope, through-hole I, and be irradiated on sample, the light reflected from sample being capable of successively via through holes III, original Sub- force microscope, lens platform, convex lens III, filter plate, half-wave plate II, analyzer, and enter photodetector, laser II The pump light of sending can successively chopped device, half-wave plate I, light ball modulator, convex lens II, lens platform, atomic force microscope, Through-hole II, and be irradiated on sample, photodetector output end connects the input terminal of lock-in amplifier I, and lock-in amplifier I's is defeated Outlet connects the input terminal of lock-in amplifier II, and the output end of lock-in amplifier II connects computer, the reference of lock-in amplifier I Signal frequency is identical as the frequency modulating signal of light ball modulator, the reference signal frequency of lock-in amplifier II and the frequency of chopper Rate is identical, and half-wave plate II and half-wave plate I can be rotated by axis of optical path.

2. a kind of Kerr effect measuring device according to claim 1, it is characterized in that: through-hole I, through-hole in the probe The diameter of II and through-hole III are 200 nanometers.