JP2941911B2 - Reflection type optical scanning tunneling microscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a reflection type optical scanning that utilizes the fact that the total reflection condition of the tip of a pickup that is scanned close to a sample surface changes depending on the state of the sample surface. Related to a tunnel microscope.

[Conventional technology]

Organic thin films such as LB film (Langmear Blodgett film)
It is promising as a high-speed optical modulator, an optical logic device, and a wavelength conversion device for application to optical electronics, particularly to optical switching equipment, and researches have been rapidly progressed worldwide in recent years. In biotechnology, elucidation of the gate mechanism of a biological cell membrane, research on a bioreactor, and the like are being vigorously advanced. Further, the necessity of observing the structures of grooves and pits on the surface of a semiconductor element, an optical disk surface or below the wavelength of light is increasing. For these studies, the 10 nm
It is necessary to establish a technology to detect the number of openings received and received in a non-contact and non-destructive manner. Conventionally, a scanning tunneling microscope is known in which a current is applied to a sample to detect a tunnel current generated on the surface of the sample and electrically observe the sample with high resolution. However, since the electric scanning tunneling microscope applies a current to the sample, the sample cannot be detected nondestructively. This point is particularly disadvantageous in observing living cells and the like. Separately, the evanescent wave generated on the sample surface when light is totally reflected inside the sample is detected by scanning the pickup,
Super-resolution microscopy or optical scanning tunneling microscopy, which observes samples in a non-contact, non-destructive manner at high resolution, was proposed in the early 1980s, and research has been steadily continued. However, the current resolution is about 100 nm (for example, Phys. Rev. B, Vol.
39, No. 1, pp. 767-770), which is still insufficient to obtain a high resolution of about 10 nm as described above.

Therefore, the present inventor has disclosed in Japanese Patent Application No. 1-230210,
We have applied for an optical scanning tunnel microscope devised for a pickup, a weak light detection system, and the like.

[Problems to be solved by the invention]

The light scanning tunneling microscope proposed in the above-mentioned Japanese Patent Application No. 1-230210 already has a very excellent feature as compared with the conventional microscope itself, but the light is transmitted from the back side of the sample and transmitted through the sample. Because of the transmission type that detects the leaked light, for example, in the case of measuring a biological cell membrane, it is necessary to separate the cell membrane from the living body when placing it on the sample stage. This may not be a true non-destructive measurement evaluation, as some of the biological cell membrane functions may be destroyed during the detachment stage. In the microscope of the above-mentioned prior application, the opening diameter of the tip of the optical fiber pickup is smaller than the wavelength of light in order to improve the resolution in the sample plane. As a result, only a small amount of the low-power evanescent light leaking from the sample surface is picked up.
Low measurement sensitivity. In the microscope of the earlier application, the heterodyne method and the photon counting method are used to improve the above-mentioned low-power light measurement sensitivity by devising the signal processing method, thereby increasing the sensitivity. Although there is a remarkable improvement, there is a problem that the measurement time is long, and therefore, there is a possibility that it is not possible to follow the movement of the living cell membrane which changes every moment.

Therefore, the present invention solves the above-mentioned problems of the conventional optical scanning tunneling microscope, and has a high resolution and a high sensitivity, for example, a reflection type capable of real-time measurement of its dynamic characteristics without destroying a biological cell membrane function. It is an object to provide an optical scanning tunneling microscope.

[Means for Solving the Problems] A first reflection-type scanning tunneling microscope according to the present invention has a pickup that is closely scanned along the surface of a sample, and the tip of the pickup excludes an area that is sufficiently smaller than the light wavelength. It detects the unevenness, refractive index distribution, or absorption rate distribution of the sample surface by measuring the phase change due to the interaction of the light reflected at the tip of the pickup with the sample surface that travels inside the pickup It is characterized by doing.

The second reflection type optical scanning tunnel microscope according to the present invention comprises:
It has a pickup consisting of an optical fiber that is scanned closely along the surface of the sample.The tip of the pickup is metal-coated except for a region that is sufficiently smaller than the light wavelength, and light of a single frequency enters from the rear end of the pickup. A single-frequency light source is arranged so as to cause a change in the phase of the incident light reflected from the tip of the pickup, and the position of the pickup with respect to the sample is controlled so that the phase is constant. It is assumed that.

Further, the third reflection-type optical scanning tunneling microscope has a pickup made of a semiconductor laser that is closely scanned along the surface of the sample, and the tip of the pickup covers an area sufficiently smaller than the light wavelength located in the light emitting area. Except for reflection coating, it is characterized in that a change in the frequency of light oscillated from the rear end of the pickup is detected and the position of the pickup with respect to the sample is controlled so that the frequency becomes constant. Things.

Further, a fourth reflection type optical scanning tunneling microscope, which is a modification of the third type, has a pickup made of a semiconductor laser that is scanned close to the surface of the sample, and the tip of the pickup has a light wavelength located in the light emitting region. It is reflectively coated except for a region that is sufficiently small compared to that of the pickup. It detects changes in the frequency of light emitted from the rear end of the pickup and controls the current injected into the semiconductor laser so that the frequency becomes constant. It is characterized by having comprised in.

Further, a fifth reflection type optical scanning tunneling microscope according to the present invention has a pickup made of an optical fiber which is closely scanned along the surface of the sample, and the front end and the rear end of the pickup are planes perpendicular to the axis, and the front end surface thereof Is metal coated except for a region that is sufficiently small compared to the light wavelength, the rear end face is coated with a partially transmissive reflective film, and the front and rear reflecting surfaces constitute a Fabry-Perot interferometer, A single-frequency light source is arranged so that light of a single frequency is incident from the rear end of the pickup, and a change in the resonance frequency of the Fabry-Perot interferometer is detected, and the pickup sample is adjusted so that the frequency becomes constant. It is characterized in that the position is controlled.

In this case, the single-frequency light source has a semiconductor laser configuration, and in order to match the oscillation frequency of the semiconductor laser with the resonance frequency of the Fabry-Perot interferometer, the semiconductor laser is changed based on the detected resonance frequency change. It is desirable that the injection current be controlled or that a part of the light resonating in the Fabry-Perot interferometer be extracted and returned directly to the semiconductor laser.

A sixth reflection type optical scanning tunneling microscope, which is a modification of the fifth type, has a pickup made of a transparent hemisphere that is closely scanned along the surface of the sample, and the tip of the pickup is constituted by the spherical surface of the transparent hemisphere. The rear end is constituted by the plane of the transparent hemisphere, and the front end surface is coated with a metal except for a region sufficiently smaller than the light wavelength, and the rear end surface is coated with a partially transmissive reflection film, and the front end reflection surface is formed. And a rear reflection surface to form a multiple reflection interferometer,
A single-frequency light source is arranged so that a single fractional part of the light is incident from the rear end of the pickup, and a change in the resonance frequency of the multiple reflection interferometer is detected, and a change in the pickup sample is performed so that the frequency becomes constant. It is characterized in that the position is controlled.

In this case, the single-frequency light source is constituted by a semiconductor laser, and the oscillation frequency of the semiconductor laser is made to match the resonance frequency of the multiple reflection interferometer. It is desirable that the injection current be controlled or that a part of the light resonating in the multiple reflection interferometer be extracted and returned directly to the semiconductor laser.

Further, the seventh reflection-type optical scanning tunneling microscope according to the present invention has a pickup made of an optical fiber that is closely scanned along the surface of the sample, and the front and rear ends of the pickup are formed of a plane perpendicular to the axis, and the front end face thereof is formed. Is metal coated except for a region that is sufficiently smaller than the light wavelength, and the rear end surface is coated with a partially transmissive reflective film.The front and rear reflecting surfaces constitute a Fabry-Perot interferometer for measurement. It has an optical fiber of the same length as the Fabry-Perot interferometer for measurement, and its front and rear ends consist of a plane perpendicular to the axis, its front end surface is entirely metal coated, and its rear end surface is partially transmissive reflective film. The front and rear reflecting surfaces are coated with a reference fabric and
The Fabry-Perot interferometer for measurement and the Fabry-Perot interferometer for reference are mounted close to the same support, and the Fabry-Perot interferometer for measurement, -Two lasers of the same configuration are arranged in the same case so that light of a single frequency is incident from the rear end of each optical fiber of the Perot interferometer,
The oscillation frequency from each laser is
The reflected light from each Fabry-Perot interferometer is synchronously detected so as to match the resonance frequency of the Perot interferometer and the Fabry-Perot interferometer for reference, and the detection signal is fed back to each laser. A part of the oscillating light from the light source is taken out and the difference between the frequencies of the two lights is measured.

An eighth optical scanning tunneling microscope, which belongs to another mode of the third type, is a pickup made of a semiconductor laser, which emits an evanescent wave generated on the surface of the sample by total reflection of light inside the sample, in a light emitting region at the tip of the pickup. Detected by a pickup coated with reflection except for a region that is sufficiently small compared to the light wavelength located at the position, and detects a change in the intensity of light emitted from the rear end of the pickup so that the intensity becomes constant. The position of the pickup with respect to the sample is controlled.

[Action]

According to the first reflection type optical scanning tunneling microscope, the tip of the pickup is metal-coated except for a region sufficiently smaller than the light wavelength, so that the light traveling in the pickup is mostly reflected, Since the impedance changes depending on the sample surface shape, the refractive index distribution, and the absorption rate distribution, the phase of the reflected light changes. Therefore, by measuring the phase change of this reflected light,
The surface shape and the like of the sample can be measured. According to this microscope, instead of detecting weak evanescent light power as in the transmission type, it detects high-power reflected light.Particularly, the phase change is measured, so sensitivity is improved and resolution is improved. improves. In addition, since it is of a reflection type, for example, its dynamic characteristics can be measured in real time without destroying the function of a living cell membrane.

According to the second reflection-type optical scanning tunneling microscope, the tip of the pickup made of an optical fiber is metal-coated except for a region sufficiently smaller than the light wavelength.
Although most of the light incident on the pickup from the rear end is reflected, the impedance of the front end of the pickup changes depending on the sample surface shape and the like, so that the phase of the reflected light changes. Therefore, by detecting the phase change of the reflected light and controlling the position of the pickup with respect to the sample so that the phase becomes constant, the surface shape and the like of the sample can be measured. According to this microscope, instead of detecting weak evanescent light power as in the transmission type, it detects high-power reflected light.Particularly, the phase change is measured, so sensitivity is improved and resolution is improved. Up. In addition, since it is of a reflection type, for example, its dynamic characteristics can be measured in real time without destroying the function of a living cell membrane.

According to the third reflection type optical scanning tunneling microscope, a pickup made of a semiconductor laser is used instead of the pickup of the second type, except for a region where the tip of the pickup is sufficiently smaller than the light wavelength located in the light emitting region. In this case, the impedance of the tip of the pickup that changes according to the shape of the sample surface or the like causes a change in the oscillation frequency of the semiconductor laser. Therefore, by detecting the change in the oscillation frequency and controlling the position of the pickup with respect to the sample so that the frequency becomes constant, the surface shape and the like of the sample can be measured. According to this microscope, a weak evanescent light power like a transmission type is not detected like the second one, but a high-power reflected light is detected. In particular, the amount of frequency change is measured. Sensitivity is further improved. The fourth type is modified so that the change in the oscillation frequency is detected and the current injected into the semiconductor laser is controlled so that the frequency becomes constant. Injection current control is the third type. Since the response speed is faster than that of position control, higher-speed measurement can be performed, which is more suitable for real-time measurement of dynamic characteristics of a biological cell membrane.

According to the fifth and sixth reflection-type optical scanning tunneling microscopes, a Fabry-Perot interferometer made of an optical fiber or a transparent hemisphere is used instead of the pickups of the second, third and fourth devices. A multi-reflection interferometer, which has a reflection coating except for a region where the tip of the pickup is sufficiently small compared to the light wavelength located in the light-emitting region. Varying pickup tip impedance changes cause interferometer resonance frequency changes. Therefore, by detecting the change in the resonance frequency and controlling the position of the pickup with respect to the sample so that the frequency becomes constant, the surface shape and the like of the sample can be measured. According to this microscope, like the second one, it does not detect a weak evanescent light power like a transmission type, but detects a high-power reflected light, and particularly measures the frequency change amount. Sensitivity is further improved.

Further, according to the seventh optical scanning tunneling microscope, a Fabry-Perot interferometer for measurement and a Fabry-Perot interferometer for reference, which constitute a pickup mounted on the same support, are arranged in the same case. Light from two lasers having the same configuration is made incident, the oscillation frequency of each laser is made to match the resonance frequency of these interferometers, a part of the oscillation light from each laser is taken out, and both lights are taken out. Since the apparatus is configured to measure the frequency difference, the effects of environmental changes such as temperature fluctuation and vibration applied to the laser and the pickup are mutually canceled, and more stable measurement can be performed. In addition, since a laser with high stability and high output such as a semiconductor-pumped YAG laser can be used as the laser, measurement with higher sensitivity can be performed.

According to the eighth optical scanning tunneling microscope, the third and fourth
Since the pickup composed of the semiconductor laser described above is operated as an optical amplifier and used as a transmission type optical scanning tunneling microscope, the intensity of the evanescent wave picked up and amplified by the pickup changes according to the sample shape and the like. Therefore, the surface shape of the sample can be measured by detecting the change in the intensity of the light that has been picked up and amplified and controlling the position of the pickup with respect to the sample so that the intensity becomes constant.
The sensitivity can be further improved as compared with the one filed earlier.

〔Example〕

Next, some embodiments of the reflection-type optical scanning tunneling microscope of the present invention will be described with reference to the drawings.

FIG. 1 shows the basic configuration of the first embodiment. The apparatus includes a pickup 1 composed of a single-mode optical fiber, a semiconductor laser 2 that emits light of a single wavelength, an optical isolator 3 that prevents light returning to the semiconductor laser 2, and a transmitted light that divides laser light from the semiconductor laser 2 into two. Is incident on the pickup 1 and the reflected light is incident on the reflection surface 5. The beam splitter 4 reflects the light reflected by the beam splitter 4 reflected by the tip 6 of the pickup 1 and the beam splitter 4 reflected by the reflection surface 5. A photodetector 7 that superimposes and interferes with the transmitted light to detect the intensity thereof; a feedback circuit 8 that amplifies a signal from the photodetector 7 and compares it with a reference value to generate an error signal; A piezoelectric element 9 for adjusting the position of the pickup 1 in a direction perpendicular to the surface of the sample S based on the signal, and a sample based on the error signal. CPU for computing and displaying the uneven shape of the surface consists of a display or the like 10, in addition to the above, it includes a pickup 1 along the surface of the sample S X-Y scanning to scanning device. The optical scanning tunnel microscope having such a configuration is of a reflection type that irradiates light from the surface side of the sample S and detects light reflected from the sample S. As shown in FIG. 2, the tip of a single-mode optical fiber composed of a core 11 and a clad 12 is polished into a conical shape and the tip of the single-mode optical fiber is made conical. Is coated with gold and chrome 13 except for the tip, and the opening diameter at the tip is very small compared to the light wavelength. This pickup 1
Is essentially the same as that proposed in the above-mentioned Japanese Patent Application No. 1-230210.

In such a reflection type optical scanning tunneling microscope,
Light incident on the core 11 of the pickup 1 from the semiconductor laser 2 via the optical isolator 3 and the beam splitter 4 is
The light leaks from the fiber tip 6 and hits the sample S (the distance between the fiber tip 6 and the surface of the sample S divided by the light wavelength), and the reflected light enters the pickup 1 again. Is very small compared to the light wavelength, so that the power of the light that leaks out from the fiber tip 6 and strikes the sample S as shown by L in FIG. Is reflected by That is, unlike the transmission type of the above-mentioned end application, total reflection of light occurs at the fiber end 6 and propagates in the fiber in a direction opposite to the outward path. However, what is most important here is that the sample S is close to the fiber tip 6, so that when the outward light sees the fiber tip 6, the impedance of the fiber tip 6 changes and is reflected. This means that the phase of the light changes (the boundary shape for the reflection of the outward light changes due to the surface shape, refractive index distribution, and absorptivity distribution of the sample S, so that the phase of the reflected light may change). Good.) Since the amount of this phase change has a value determined by the surface shape, refractive index distribution, and absorptivity distribution of the sample, the phase change is measured by causing the reflected light and the reference light to interfere with each other. The shape, refractive index distribution, and absorption rate distribution can be measured. That is, the above-mentioned reflection type optical scanning tunneling microscope does not detect weak evanescent light power as in the transmission type, but detects high power reflected light, and particularly measures the phase change amount. , The sensitivity is improved. In other words,
The sensitivity is improved by increasing the optical power to be picked up and measuring the phase change, instead of devising a signal processing method as in the transmission type.

In the above-described phase change measurement, as shown in FIG. 1, the light is divided into two in advance by a prism beam splitter 4 disposed between the semiconductor laser 2 and the pickup 1, and one of them is put into the pickup 1, The reflected light having a phase change amount depending on the shape or the like is obtained. The other light is provided on one surface of the beam splitter 4 and reflected by the reflecting surface 5, and is combined again with the above-mentioned reflected light in the beam splitter 4. The combined lights interfere with each other, and the interference intensity depends on the phase difference between the two lights. Therefore,
By measuring the interference intensity with the photodetector 7, the amount of phase change can be measured.

An error signal is sent to the piezoelectric element 9 via the feedback circuit 8 so that the phase detected as described above becomes a constant value, and the position of the pickup 1 is adjusted in a direction perpendicular to the sample S surface. From this error signal and the position signal of the XY scanning device of the pickup (not shown),
The point that the surface shape and the like of the sample are calculated and displayed on the U, display, and the like 10 is the same as in a conventional scanning tunnel microscope. In addition, it is also possible to measure a planar shape or the like by detecting only a phase change without performing feedback as described above.

As described above, in the above-mentioned reflection-type optical scanning tunneling microscope, the reflected light returned from the optical fiber pickup 1 is used for phase measurement. However, since this power is almost the same as the optical power sent to the pickup 1, the measurement sensitivity is high. Is high. The phase measurement is a conventionally established interferometry, and has an accuracy of about 1/100 radian. further,
Since the amount of phase change can be converted into a rotation of a polarization plane, frequency shift, and the like and measured, higher accuracy can be expected.

In addition, as for the tip shape of the pickup 1, as shown in FIG.
This is not limited to the case where the tip of the cone is coated with a metal other than the tip. For example, the tip of the single mode fiber is cut perpendicularly to the axis, the cut surface is coated with a reflective film, and the opening corresponding to the core has an aperture diameter of ≪. An aperture opening may be used so as to have a wavelength of light.

Next, referring to FIG. 3, another embodiment of a reflection type optical scanning tunneling microscope will be described. The second one for increasing the sensitivity is a reflection type optical scanning tunneling microscope which uses the semiconductor laser 15 itself as a light source and pickup instead of the optical fiber pickup 1 shown in FIG. 3, as shown in FIG. Compared to the semiconductor laser of FIG. 1, this semiconductor laser 15 not only functions as a light source like the semiconductor laser 2 of FIG. 1, but also functions as a pickup. That is, the emission end of the semiconductor laser 15 on the sample S side is coated with a reflection film 21 having an emission opening, and is processed so that the diameter of the emission opening is equal to the wavelength of light. Like the tip 6, light leaks only slightly from the emission opening of the semiconductor laser 15, and is totally reflected on the opposite side of the semiconductor laser 15. However, the semiconductor laser 15
On the other hand, the impedance on the other hand, that is, the reflectance and the refractive index of the end face change. In particular, since the phase of the light reflected from the end face changes due to the change in the refractive index of the after-fire, the oscillation frequency of the semiconductor laser 15 changes. Therefore, by measuring the change in the oscillation frequency, the shape, the refractive index distribution, and the absorption rate distribution of the sample surface can be measured. Here, the interferometer as in the case of the phase change measurement shown in FIG. 1 is no longer necessary. For example, as shown in FIG. 3, another frequency reference semiconductor laser 17 is disposed, and the half mirror 18 is disposed. The change in the oscillation frequency may be detected by employing a heterodyne method that takes a beat with the reference light from the frequency reference semiconductor laser 17 via the semiconductor laser. Alternatively, as a simpler method, if a stable Fabry-Perot interferometer is arranged as a frequency discriminator in front of the photodetector 7, the amount of frequency change can be measured with high sensitivity. In the case of this embodiment, it is possible to eliminate the influence of fluctuation of the optical path length of the interferometer due to mechanical vibration and the like. It is well known that the frequency variation can be measured with the highest accuracy among all physical quantity measurements. Therefore, the microscope in FIG. 3 measures the surface shape of the sample S with higher accuracy. it can. In order to improve the measurement accuracy of this microscope, it is advantageous to use a semiconductor laser 15 whose frequency is stable (the spectrum width is narrow). In FIG. 3, such an apparatus for measuring an oscillation frequency change is schematically shown as a frequency change measurement system 16.

In the case of the microscope shown in FIG. 3, two methods are conceivable for measuring the three-dimensional shape and the like of the sample S. The first method is to attach the semiconductor laser 15 to the piezoelectric element 9 in the same manner as in the conventional STM, and to adjust the frequency of the semiconductor laser 15 in the vertical direction (the The semiconductor laser 15 is two-dimensionally scanned in the sample plane while adjusting the position of (1). To do this,
Connect switch 19 to the terminal of
An error signal from the piezoelectric element 9 may be given to the piezoelectric element 9. As a signal for monitoring the three-dimensional shape or the like of the sample S, a pixel signal given to the piezoelectric element 9 is used. In the second method, the semiconductor laser 15 is attached to the piezoelectric element 9, but the switch 19 is switched to the
Keep the 15 vertical positions unchanged. Then, the semiconductor laser 15 is two-dimensionally scanned on the sample surface while automatically controlling the output current of the injection current source 20 of the semiconductor laser 15 so as to compensate for the frequency change. Since the injection current control has a faster response speed than the first piezoelectric element control, higher-speed measurement can be performed, which is more suitable for real-time measurement of dynamic characteristics of a biological cell membrane. In particular, this second measurement method corresponds to using a tunable optical amplifier for the pickup. That is, the injection current is controlled so that the resonance frequency of the resonator of the semiconductor laser 15 always tunes (coincides) with the pickup light frequency, so that the tunable resonator is used. Further, since this resonator includes a semiconductor gain medium for semiconductor laser oscillation, it works as an amplifier for pickup light. That is, the semiconductor laser 15 functions as an optical amplifier in which impedance matching is established at the pickup end face. In the first method, the semiconductor laser 15
May be considered as a tunable optical amplifier. At this time, the tuning is realized by controlling the piezoelectric element 9.

The reflection type optical scanning tunnel microscope of FIG. 3 is similar to that of FIG.
We use light that is totally reflected at the exit end of the 15
Since a tunable optical amplifier is used, optical power utilization efficiency is high. Further, when combined with the above-described frequency change measurement system, the measurement sensitivity is greatly improved. In the transmission type optical scanning tunneling microscope of the prior application, the optical power to be picked up may be reduced to several to several tens of pW, but in the reflection type optical scanning tunneling microscope of the present invention, a laser power of several mW is used. can do. That is, the sensitivity is about 10 ⁹
To improve twice. Therefore, the aperture area can be made smaller than that of the pickup of the earlier application, and the resolution (resolution) in the sample plane is further improved, which is far greater than that of a conventional scanning tunneling microscope (STM) using a tunnel current. It is expected to have excellent performance.

The light scanning tunneling microscope of the present invention can be of a transmission type as shown in FIG. In that case, similarly to the invention of the earlier application, the evanescent light transmitted through and exuded from the sample S is not an optical fiber, but
Pick-up is performed by the same semiconductor laser 15 as shown in FIG. However, such that the oscillation frequency of the semiconductor laser 15 matches (tunes) with the frequency of the evanescent light,
Adjust the injection current. Then, as described above, since this semiconductor laser 15 functions as a tunable optical amplifier in which impedance matching is established at the pickup end face, evanescent light does not scatter at the end face, and the semiconductor laser 15 does not scatter.
All are picked up by 15 and amplified in the semiconductor laser 15. In the case of this transmission type, a light source and a semiconductor laser 15 for pickup are used separately, but the use of the latter semiconductor laser 15 as a tunable optical amplifier has long been known in other types of lasers. This is an application of a phenomenon called “injection locking”. Attempts to use semiconductor lasers as such optical amplifiers have been made in coherent optical communication systems. In the case of the transmission type shown in FIG. 4, the vertical position of the piezoelectric element 9 on which the semiconductor laser 15 is mounted is automatically controlled so that the output power from the semiconductor laser 15 for pickup becomes constant. And two-dimensionally sweep the surface of the sample appropriately.

By the way, also in the optical scanning tunneling microscope, before observing the ultrafine shape of the sample S as the optical scanning tunneling microscope, it is necessary to see a slightly wide area in advance to narrow the observation field. Further, it is necessary to provide a mechanism for controlling the distance between the sample S and the sample S so as to be constant. For these reasons, in the light scanning tunneling microscope of FIGS. 3 and 4, as shown in FIG.
A probe (tunnel tip) 22 made of a metallic protrusion is attached to the end face of the semiconductor laser 15 facing the sample S, and a power source 23
Voltage is applied between the sample S and the sample S, and the sample S and the probe
A conventional electric scanning tunnel is constructed by measuring a tunnel current flowing between the electrodes 22 and feeding it back to the piezoelectric element 9 (FIGS. 3 and 4) so that the value becomes a predetermined current value. It can be used as a microscope. However, the electrical scanning tunnel microscope can be used only when the sample S is conductive.

As described above, the optical scanning tunneling microscope of FIG.
The optical scanning tunneling microscope shown in FIG. 4 and FIG. 4 also increases the signal light power confidence rather than improving the detection sensitivity of low-power light by devising a signal processing method as in the above-mentioned prior application. It is. Those of the present invention,
This is effective for improving the lateral resolution and reducing the measurement time. Also,
3 and 4 partially overlap the basic principle of FIG. 1, but differ in that the semiconductor laser itself is used for pickup and that tuned amplification is performed using the semiconductor laser.
In addition, since a frequency change is measured instead of a phase change, it is advantageous in terms of accuracy. Coating a reflective film with a small opening on the end face of the semiconductor laser is not always an easy technique, but it is possible by improving the semiconductor laser element manufacturing technique.

Next, a reflection type optical scanning tunneling microscope according to another embodiment of the present invention will be described. First, as shown in FIG. 6, both ends of an optical fiber 24 are polished perpendicular to the fiber axis, and a reflective film 21 having a partially transmitting reflective film 25 at the rear end and a light exit opening similar to that of FIG. Deposit to form a high precision Fabry-Perot interferometer. Also in this case, the exit aperture of the reflection film 21 is processed so that the diameter of the exit aperture is equal to the wavelength of the light, and the Fabry-Perot interferometer according to the distance from the sample S similarly to the principle of FIG. Are shifted. By measuring this shift, the surface shape, refractive index distribution, and absorption rate distribution of the sample S can be measured. That is, as in the case of FIG. 3, a resonance type pickup is formed. In order to measure the deviation of the resonance frequency, the light from the semiconductor laser 2 is Fabry-
The laser beam frequency is adjusted to Fabry
The injection current to the semiconductor laser 2 is automatically controlled by an electronic circuit so as to match the resonance frequency of the Perot interferometer. For this purpose, the frequency of the oscillating laser light is modulated by modulating the current from the injection power supply 20 with the high frequency from the high-frequency oscillator 26 and injecting it into the semiconductor laser 2.
The output of the photodetector 7, which detects light from the Perot interferometer, is applied to a synchronous detector 27, which is synchronized with a high frequency from a high frequency oscillator 26, and is synchronously detected to obtain a resonance curve of the Fabry-Perot interferometer. The output of the synchronous detector 27 is fed back to the injection current source 20 to control the semiconductor laser injection current so that the differentiated signal is obtained and the oscillation frequency of the laser light is stabilized at the center frequency. At the same time, the distance between the sample S and the tip of the Fabry-Perot interferometer is controlled by applying the output of the synchronous detector 27 to the piezoelectric element 9. In this state, while sweeping the optical fiber 24 in the plane of the sample S, the synchronous sweeper 27
When the automatic control signal is supplied to the CPU 10, the three-dimensional shape and the like of the surface of the sample S are displayed. The in-plane resolution of the microscope is determined by the aperture diameter of the reflective film 21 at the tip of the Fabry-Perot interferometer.

By the way, instead of the automatic electrical control as in the above embodiment, as shown in FIG.
The light resonating in the Fabry-Perot interferometer composed of the reflection films 21 and 25 is directly fed back to the semiconductor laser 2 so that the laser oscillation frequency is automatically drawn into the resonance frequency of the Fabry-Perot interferometer and fixed. can do. Therefore, in this case, there is no need to modulate the laser frequency of the semiconductor laser 2 as in the case of FIG. To do this, the optical fiber 24 constituting the Fabry-Perot interferometer and the auxiliary optical fiber
An optical fiber directional coupler 28 comprising an optical fiber 29 and light from the semiconductor laser 2 is input into the Fabry-Perot interferometer through the auxiliary optical fiber 29 of the directional coupler 28,
Further, the light resonating therein is extracted through it. Since almost no light resonating in the Fabry-Perot interferometer can be extracted through the reflection film 25 on the end face, a configuration using such a directional coupler 28 is employed. The laser light from the semiconductor laser 2 is applied to the half mirror 1
In the same manner as in the case of FIG. 3, the light is interfered with the reference light from another frequency reference semiconductor laser 17 via 8 ', photoelectrically converted by the photodetector 7, and the frequency of the beat signal (heterodyne frequency). ) Is measured by the frequency counter 30. Using this measured value, the piezoelectric element 9 is controlled to control the distance between the optical fiber 24 and the sample S, and a control signal at that time is given to the CPU 10 to obtain the three-dimensional shape of the sample S in the same manner as described above. Etc. can be displayed. It is desirable that the incident end and the outgoing end of the auxiliary optical fiber 29 be cut so as to be inclined with respect to the optical axis as shown in the figure to prevent interference in the auxiliary optical fiber 29.

By the way, if the optical fiber 24 is used as a resonator as shown in FIG. 7, the optical fiber is liable to be deformed due to a change in temperature, vibration or the like, so that the resonance frequency may be changed. Therefore, the interferometer shown in FIG. 8 can be used as a mode that is more stable than in the case of FIG. 7 and that makes it easy to create a minute aperture in the reflection film at the tip of the interferometer. It is a small fiber (a few mm in diameter)
A glass hemisphere 31 is used, a reflective film 32 having an emission opening having an emission opening diameter and a wavelength of light is deposited on the spherical surface, and a partially transmitting reflection film 33 is deposited on a flat surface. In order to provide such a small exit opening in the reflective film 32 on the spherical surface, for example, a simple electro-etching method (Appl. Phys.
tt. 55 (22) 27, p. 2366, November 1989) may be used. In the figure, reference numeral 34 denotes an optical axis adjustment auxiliary optical fiber, which is used to adjust the optical axis so that the laser beam from the semiconductor laser 2 is constantly irradiated to the opening having the interference diameter. With this configuration, the glass hemisphere
Since the resonance light in the resonator composed of the partial transmission reflection film 33 and the reflection film 32 can be extracted through the partial transmission reflection film 33, the directional coupler shown in FIG. 7 is not required. FIG. 8 does not show a light detection circuit, a control circuit, and the like, but has the same configuration as that of FIG. When the pickup configuration is changed in this way, the laser beam cross-sectional area in the hemisphere 31 is about 10 ⁶ times larger than that in the optical fiber 24 in FIG. Is smaller, and the measurement sensitivity is lower than that in the case of FIG. The interferometer using the glass hemisphere shown in FIG. 8 can be used instead of the Fabry-Perot interferometer shown in FIG.

Also in FIGS. 6 to 8, a probe (tunnel tip) 22 made of a metallic projection for use as an electric scanning tunnel microscope as shown in FIG. The distance between the conductive sample S and the pickup may be controlled to be constant.

The reflection-type optical scanning tunneling microscope shown in FIGS. 6 to 8 is also similar to those shown in FIGS. 1, 3, and 4 by devising the signal processing method as described in the earlier application. Rather than improving the detection sensitivity of low-power light, it increases the signal light power itself.
This is effective for reducing the measurement time. 6 to 8 are reflection type optical scanning tunneling microscopes having a very high resolution in the thickness direction, similar to those shown in FIG. 3, and have sufficient optical power. Having. It is not necessary to provide a reflecting surface constituting the interferometer separately from the optical fiber as compared with the one shown in FIG. 1, and it is possible to eliminate a measurement error caused by vibration of the reflecting surface and the like.
It has features such as easy polishing, coating and opening of the optical fiber end face. 3 and 4, the end face of the optical fiber is easier to coat and form an opening than the end face of the semiconductor laser, and the price as a pickup is lower for an optical fiber than for a semiconductor laser. There is a feature. Regarding the resolution, the one in FIG. 6 may be inferior to the one in FIG. 3 in the sample thickness direction, but the one in FIG. 7 is equivalent to that in FIG. 8 has approximately the same performance as that of FIG. 6, but it is easier to create an opening, and it can be said that it is a simplified type.

Incidentally, in any of the above embodiments, there is a possibility that the resonance frequency of the interferometer fluctuates due to temperature fluctuation, vibration, etc. of the optical fiber, glass hemisphere or the like.
The power of currently available single-mode semiconductor lasers is less than several tens of mW, so that
The optical power incident on the Fabry-Perot interferometer or the like is about several mW, and the measurement sensitivity may be reduced. Therefore,
By using a small-diameter YAG laser pumped by a semiconductor laser as the laser, it is more stable against environmental changes such as temperature fluctuations and vibrations.
It is possible to realize a reflection type optical scanning tunnel microscope capable of measuring with higher sensitivity. That is, as shown in FIG. 9, two lasers 351 and 352 of the same type are prepared, housed in a common constant temperature case 36, and are subjected to the same external influence such as temperature fluctuation. As the lasers 351 and 352, it is advantageous to use a semiconductor laser whose frequency is stabilized and whose oscillation line width is narrowed, or a small YAG laser pumped by a semiconductor laser. In particular, the latter semiconductor laser-pumped small YAG laser has low noise even when not controlled, and has a narrow oscillation line width. Figure 10 shows a perspective view of an example.
It is shown in the figure (Optics Letters Vol. 14, 12, pp. 618-620).
0.7 × 1.0 × 2.0 mm ³ was used as the YAG crystal 41, and this crystal 41 was used.
The oscillation wavelength is tuned by adjusting the stress by applying a stress by the PZT. The excitation light uses light from a semiconductor laser of 0.81 μm,
The output is infrared light of 1.3 μm. The heat sink 43
Is the same as that of the semiconductor laser,
Very small. Returning to FIG. 9, the laser 35
The light from 1, 352 passes through the optical isolators 3 and 3, the half mirrors 18 and 18 ', respectively, enters the phase modulators or frequency modulators 361 and 362 made of, for example, an electro-optic crystal, and undergoes phase or frequency modulation. Each polarizing beam splitter
Circularly polarized light passes through 371, 372 and quarter-wave plates 381 and 382, and enters the optical fiber Fabry-Perot interferometers F1 and F2 from the partial transmission reflection film 25. As in the case of FIG. 6, the optical fiber Fabry-Perot interferometer F1 for measurement is polished at both ends of the optical fiber 24 perpendicular to the fiber axis, and has a partially transmitting / reflecting film 25 at the rear end and an aperture diameter at the front end. It is formed by vapor deposition of a reflective film 21 having an emission opening that becomes the wavelength of light,
Also, for reference, an optical fiber Fabry-Perot interferometer F2
Is adjusted to resonate at the same frequency as F1, but no aperture is provided in the reflective film 39 deposited on its tip. These two optical fiber Fabry-Perot interferometers F1 and F2 are
It is installed at 40 and is affected by temperature fluctuation, vibration, etc. at the same time. Optical fiber Fabry
The light reflected from the Perot interferometers F1 and F2 becomes circularly polarized light turning in the reflection direction, and is photoelectrically converted by the photodetectors 71 and 72 through quarter-wave plates 381 and 382 and polarization beam splitters 371 and 372. In the synchronous sweepers 271 and 272, synchronous detection is performed at a high frequency applied to the phase modulator or the frequency modulator 361 or 362, and the detected signal is fed back to the lasers 351 and 352,
Automatic control is performed so that the oscillation frequencies of 351 and 352 are fixed to the resonance frequencies of the optical fiber Fabry-Perot interferometers F1 and F2, respectively. In this state, the surface shape of the sample S is measured by relatively moving the optical fiber Fabry-Perot interferometer F1 constituting the pickup along the surface of the sample S. The measuring method is to cause the oscillation lights of the lasers 351 and 352 to interfere with each other through the half mirrors 18 and 18 ', detect the heterodyne frequency therebetween by the photodetector 73, and measure the change in the heterodyne frequency by the frequency counter 30. , The surface shape of the sample S and the like can be understood. As described above, this embodiment is a differential method using two equivalent lasers and two optical fibers, and the effect of fluctuations due to temperature fluctuations, vibrations, and the like of the laser and the optical fiber appears at the heterodyne frequency. I won't. In addition, small semiconductor laser excitation
Since a YAG laser can be used, high power can be achieved, and a decrease in measurement sensitivity due to low optical power can be prevented.

When a semiconductor laser having a wavelength of 1.3 μm or a small YAG laser pumped by a semiconductor laser is used, a polarization-maintaining optical fiber practically used in this wavelength band can be used as the optical fiber 24, and the Fabry-Perot interferometers F1 and F2 can be used.
The finesse can be improved. Further, if a multi-core optical fiber for optical communication is used, Fabry-Perot interferometers F1 and F2 can be realized by two cores in the same clad. Further, since the power of the laser of the semiconductor laser-excited small YAG is large, the same sample can be measured at two wavelengths by inserting and removing the nonlinear optical crystal, so that the refractive index distribution and the absorption ratio distribution of the sample can be measured. Optical fiber 24
In the case where a rough measurement is made such that the fluctuation of the above is negligible, the Fabry-Perot interferometer F2 may be omitted. When the sample S is an organic ultra-thin film having a low reflectance, a metal flat plate P is laid under the sample S as shown in FIG. It is preferable to measure the shape, the refractive index distribution, and the absorption rate distribution of the sample S by using

〔The invention's effect〕

In the first reflection type optical scanning tunneling microscope, the tip of the pickup is metal-coated except for a region sufficiently smaller than the light wavelength, so that the light traveling in the pickup is mostly reflected, Since the impedance changes depending on the sample surface shape, the refractive index distribution, and the absorption rate distribution, the phase of the reflected light changes. Therefore, by measuring the phase change of the reflected light, the surface shape and the like of the sample can be measured. According to this microscope, instead of detecting weak evanescent light power as in the transmission type, it detects high-power reflected light.Particularly, the phase change is measured, so sensitivity is improved and resolution is improved. improves. In addition, since it is of a reflection type, for example, its dynamic characteristics can be measured in real time without destroying the function of a living cell membrane.

In the second reflection type optical scanning tunneling microscope, the tip of the pickup made of an optical fiber is metal-coated except for a region sufficiently smaller than the light wavelength, so that the light incident on the pickup from the rear end is mostly reflected. However, since the impedance at the tip of the pickup changes depending on the shape of the sample surface, the phase of the reflected light changes. Therefore, by detecting the phase change of the reflected light and controlling the position of the pickup with respect to the sample so that the phase becomes constant, the surface shape and the like of the sample can be measured. According to this microscope, instead of detecting weak evanescent light power as in the transmission type, it detects high-power reflected light.Particularly, the phase change is measured, so sensitivity is improved and resolution is improved. improves. In addition, since it is of a reflection type, for example, its dynamic characteristics can be measured in real time without destroying the function of a living cell membrane.

In the third reflection type optical scanning tunneling microscope, the second
Instead of the pickup of the above, a pickup made of a semiconductor laser, whose tip is reflectively coated except for a region sufficiently smaller than the light wavelength located in the light emitting region, is used, so that the sample surface shape is used. The impedance change at the tip of the pickup that changes according to the above causes a change in the oscillation frequency of the semiconductor laser. Therefore, by detecting the change in the oscillation frequency and controlling the position of the pickup with respect to the sample so that the frequency becomes constant, the surface shape and the like of the sample can be measured. According to this microscope, like the second one, it does not detect a weak evanescent light power like a transmission type, but detects a high-power reflected light, and particularly measures the frequency change amount. Sensitivity is further improved. The fourth type is modified so that the change in the oscillation frequency is detected and the current injected into the semiconductor laser is controlled so that the frequency becomes constant. Since the response speed is faster than that of the position control, the measurement can be performed at a higher speed, which is more suitable for the real-time measurement of the dynamic characteristics of the biological cell membrane.

In the fifth and sixth reflection-type optical scanning tunneling microscopes, instead of the pickups of the second, third, and fourth types, a Fabry-Perot interferometer made of an optical fiber or a transparent hemisphere is used. Since a pickup comprising a multi-reflection interferometer that has been subjected to reflection coating except for a region whose tip is sufficiently small compared to the light wavelength located in the light emitting region,
A change in the impedance of the pickup tip that changes according to the sample surface shape causes a change in the resonance frequency of the interferometer. Therefore, by detecting the change in the resonance frequency and controlling the position of the pickup with respect to the sample so that the frequency becomes constant, the surface shape and the like of the sample can be measured. According to this microscope, like the second one, it does not detect a weak evanescent light power like a transmission type, but detects a high-power reflected light, and particularly measures the frequency change amount. Sensitivity is further improved.

Further, in the seventh optical scanning tunneling microscope, a Fabry-Perot interferometer for measurement and a Fabry-Perot interferometer for reference, which constitute a pickup mounted on the same support, are arranged in the same case. Light from two lasers having the same configuration is made incident, the oscillation frequency of each laser is made to match the resonance frequency of these interferometers, a part of the oscillation light from each laser is taken out, and both lights are taken out. Since it is configured to measure the frequency difference,
The effects of environmental changes on temperature fluctuations, vibrations, and the like applied to the laser and the pickup are mutually canceled, and more stable measurement can be performed. In addition, since a laser with high stability and high output such as a semiconductor-pumped YAG laser can be used as the laser, measurement with higher sensitivity can be performed.

In the eighth optical scanning tunneling microscope, the pickup composed of the third and fourth semiconductor lasers acts as an optical amplifier and is used as a transmission type optical scanning tunneling microscope, so that the evanescent wave picked up and amplified by the pickup is used. Varies depending on the sample shape and the like. Therefore, the surface shape of the sample can be measured by detecting the change in the intensity of the light that has been picked up and amplified and controlling the position of the pickup with respect to the sample so that the intensity becomes constant. The sensitivity can be further improved as compared with the one filed earlier.

Therefore, the optical scanning tunneling microscope of the present invention can measure its dynamic characteristics in real time with high resolution and high sensitivity without destroying, for example, the function of a living cell membrane.
High sensitivity, high stability, high speed, high resolution, non-contact, non-destructive for observing the fine shape of the surface of semiconductor devices, optical disks, etc., elucidating the gate mechanism of biological cell membranes, researching bioreactors, etc. As a detection means,
It is extremely effective.

Furthermore, the optical scanning tunneling microscope of the present invention not only measures the shape and the like, but also utilizes the light leaked from the emission opening at the tip of the pickup, and performs cell surgery at the molecular level by manipulating and fixing DNA and the like, synthesis, It can be expected to be applied as a processing device such as crystal growth for each single atom.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of one embodiment of a reflection type optical scanning tunneling microscope according to the present invention, FIG. 2 is an enlarged view of the tip of the pickup of FIG. 1, and FIG. FIG. 4 is a diagram showing the configuration of the embodiment of FIG. 3, which is a transmissive type, and FIG. 5 is a diagram showing the configuration of FIG. 3 and FIG.
FIGS. 6 to 9 show a configuration of another embodiment of the reflection type optical scanning tunneling microscope of the present invention. The figure is a perspective view of one example of a semiconductor laser pumped small YAG laser. 1. Pickup consisting of single mode optical fiber,
2 ... semiconductor laser, 3 ... optical isolator, 4 ... beam splitter, 5 ... reflecting surface, 6 ... pickup tip, 7 ... photodetector, 8 ... feedback circuit, 9
…… Piezoelectric element, 10 …… CPU, display, etc. 11 …… Core, 12 …… Clad, 13 …… Metal coating, 15 ……
Semiconductor laser, 16… Frequency change measurement system, 17 ……
Frequency reference semiconductor laser, 18, 18 '... half mirror,
19: Switch, 20: Injection current source, 21: Reflective film with exit aperture, 22: Tip (tunnel tip), 24:
Optical fiber, 25: Partially transmissive reflection film, 26: High frequency oscillator, 27: Synchronous detector, 28: Optical fiber directional coupler, 29: Auxiliary optical fiber, 30: Frequency counter, 31: Glass hemisphere, 32 ... reflecting film with exit aperture, 33 ... partially transmissive reflecting film, 34 ... optical axis adjustment auxiliary optical fiber, 36 ... constant temperature case, 39 ... reflecting film, 40 ... support base, 41 ... YAG crystal , 42 …… PZT, 43 …… heat sink,
71, 72, 73 ... Photodetector, 271, 272 ... Synchronous detector, 35
1, 352: laser, 361, 362: phase modulator or frequency modulator, 371, 372: polarizing beam splitter, 381, 3
82: quarter-wave plate, S: sample, P: metal plate,
F1, F2 …… Optical fiber Fabry-Perot interferometer

Claims (12)

(57) [Claims] 1. A pickup having a pickup which is closely scanned along a surface of a sample, and a tip of the pickup is metal-coated except for an area sufficiently smaller than an optical wavelength, and travels inside the pickup and is reflected by the tip of the pickup. A reflection-type optical scanning tunneling microscope characterized in that a phase change due to the interaction of light with a sample surface is measured to detect the uneven shape, refractive index distribution, or absorption rate distribution of the sample surface. 2. A pickup comprising an optical fiber which is scanned close to the surface of the sample, wherein the tip of the pickup is metal-coated except for an area which is sufficiently smaller than the light wavelength, and has a single point from the rear end of the pickup. A single-frequency light source is arranged so that light of a frequency is incident thereon, and a phase change of reflected light from the tip of the pickup of the incident light is detected, and the position of the pickup with respect to the sample is controlled so that the phase becomes constant. A reflection type optical scanning tunneling microscope characterized in that: 3. A pickup comprising a semiconductor laser which is scanned close to the surface of the sample, wherein the tip of the pickup is reflection-coated except for a region sufficiently smaller than a light wavelength located in a light emitting region. A reflection type optical scanning tunneling microscope characterized in that a change in the frequency of light emitted from the rear end of the pickup is detected and the position of the pickup with respect to the sample is controlled so that the frequency becomes constant. 4. A pickup comprising a semiconductor laser which is closely scanned along a surface of a sample, wherein a tip of the pickup is reflection-coated except for a region sufficiently smaller than a light wavelength located in a light emitting region. A reflection-type optical scanning tunneling microscope, wherein a change in the frequency of light oscillated from a rear end of a pickup is detected and a current injected into a semiconductor laser is controlled so that the frequency becomes constant. 5. A pickup comprising an optical fiber which is scanned close to the surface of the sample, comprising:
The rear end consists of a plane perpendicular to the axis, and the front end surface is metal-coated except for a region that is sufficiently smaller than the light wavelength,
After that, the end face is coated with a partially transmissive reflective film,
A Fabry-Perot interferometer is configured by the front-end reflection surface and the rear-end reflection surface, and a single-frequency light source is arranged so that light of a single frequency is incident from the rear end of the pickup. A reflection type optical scanning tunneling microscope characterized in that a change in resonance frequency is detected and the position of the pickup with respect to the sample is controlled so that the frequency becomes constant. 6. The semiconductor laser according to claim 1, wherein the single-frequency light source comprises a semiconductor laser, and the semiconductor laser is changed based on a detected resonance frequency change so that an oscillation frequency of the semiconductor laser matches a resonance frequency of the Fabry-Perot interferometer. 6. The apparatus according to claim 5, wherein the laser injection current is controlled.
The reflective light scanning tunneling microscope as described. 7. The single-frequency light source comprises a semiconductor laser, and resonates in the Fabry-Perot interferometer so that the oscillation frequency of the semiconductor laser matches the resonance frequency of the Fabry-Perot interferometer. 6. The reflection-type optical scanning tunneling microscope according to claim 5, wherein a part of the light is extracted and directly returned to the semiconductor laser. 8. A pickup having a transparent hemisphere which is closely scanned along a surface of a sample, wherein a tip of the pickup is formed by a spherical surface of the transparent hemisphere, and a rear end is formed by a plane of the transparent hemisphere. The front end surface is metal coated except for a region sufficiently smaller than the light wavelength, and the rear end surface is coated with a partially transmissive reflection film, forming a multiple reflection interferometer with the front reflection surface and the rear reflection surface. A single-frequency light source is arranged so that light of a single frequency is incident from the rear end of the pickup, and a change in the resonance frequency of the multiple reflection interferometer is detected, so that the sample of the pickup is kept constant. A reflection-type light scanning tunneling microscope, wherein the position is controlled with respect to light. 9. The semiconductor laser according to claim 1, wherein the single-frequency light source comprises a semiconductor laser, and the oscillation frequency of the semiconductor laser coincides with the resonance frequency of the multiple reflection interferometer. 9. The reflection type optical scanning tunneling microscope according to claim 8, wherein the injection current is controlled. 10. A light resonating in the multiple reflection interferometer, wherein the single frequency light source is constituted by a semiconductor laser, and the oscillation frequency of the semiconductor laser is matched with the resonance frequency of the multiple reflection interferometer. 9. A reflection-type light scanning tunneling microscope according to claim 8, wherein a part of the light scanning tunneling microscope is configured to be directly returned to the semiconductor laser. 11. A pickup comprising an optical fiber which is closely scanned along the surface of a sample, wherein the front and rear ends of the pickup are planes perpendicular to an axis, and the front end of the pickup has an area sufficiently smaller than the light wavelength. Except for the metal coating, the rear end surface is coated with a partially transmissive reflective film, and the front and rear reflecting surfaces constitute a Fabry-Perot interferometer for measurement, the same as the Fabry-Perot interferometer for measurement. It has a length of optical fiber, and its front and rear ends consist of a plane perpendicular to the axis.The front end surface is entirely coated with metal, and the rear end surface is coated with a partially transmissive reflection film. The Fabry-Perot interferometer for reference is composed of the end reflection surface, and the Fabry-Perot interferometer for measurement and the Fabry-Perot interferometer for reference are located close to the same support. Two Fabry-Perot interferometers for measurement and two Fabry-Perot interferometers for reference are placed in the same case so that light of a single frequency is incident from the rear end of each optical fiber Then, the reflected light from each Fabry-Perot interferometer is synchronously detected so that the oscillation frequency from each laser matches the resonance frequency of the Fabry-Perot interferometer for measurement and the resonance frequency of the Fabry-Perot interferometer for reference. A reflection-type optical scanning tunneling microscope, wherein a signal is fed back to each laser, a part of oscillation light from each laser is taken out, and a frequency difference between the two lights is measured. 12. An evanescent wave generated on the surface of the sample due to total reflection of light inside the sample, except for an area of a pickup made of a semiconductor laser, which is sufficiently smaller than a light wavelength located in a light emitting area at the tip of the pickup. It is configured to detect the change in the intensity of light emitted from the rear end of the pickup by detecting with a pickup coated with reflection, and to control the position of the pickup with respect to the sample so that the intensity becomes constant. Optical scanning tunnel microscope.