TECHNICAL FIELD

The present invention relates to a scanning type probe microscope and also relates to a control device for a scanning type probe microscope.

BACKGROUND ART

In a scanning type probe microscope, a cantilever beam provided with a probe called “cantilever” is used. The deflection or the change in the vibration of the cantilever is converted into a change in the reflected light of the laser irradiated on the rear surface of the cantilever and detected by a photodetector. The photodetector detects the changes in the position, the intensity, the phase, and the like of the reflected light and converts them into various physical information (see, for example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2000-346782).

In a scanning type probe microscope, since the reflected light of the laser is used, before the measurement, an optical axis adjustment of the laser light is required so that the laser light is correctly emitted to the rear surface of the cantilever. Since the cantilever is small, the tolerance for the adjustment is on the order of microns. As a manual optical axis adjustment is difficult and time-consuming, auto-adjustment scanning type probe microscopes are increasing.

In an optical axis auto-adjustment, the cantilever and the spot of the beam of the laser light are observed with an optical microscope, a CCD (Charge Coupled Device) imaging unit, or the like, and the optical component, the laser light source, or the cantilever is automatically moved so that the spot of the beam is emitted to the rear surface of the cantilever.

Prior Art Document

Patent Document

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2000-346782

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

However, if the spot of the beam of the laser light is in a position that cannot be detected by the optical microscope or the CCD-imaging unit, the optical axis automatic-adjustment cannot be performed because the movement target and the movement direction cannot be specified.

Although it is possible to perform the adjustment by switching to a manual mode, the position of the spot of the beam is unknown. For this reason, it is required to start by moving the laser light source randomly to locate the position of the movement target, which makes the operation complex and inefficient.

Under the circumstances, it is an object of the present invention to provide a scanning type probe microscope capable of easily performing an optical axis adjustment and a control device of a scanning type probe microscope.

Means for Solving the Problem

A scanning type probe microscope according to one aspect of the present invention is provided with:

a cantilever provided on a tip end thereof with a probe; an optical system configured to emit laser light to the cantilever and detect the laser light reflected by the cantilever;

a measurement unit configured to measure characteristics of a sample based on a displacement of the cantilever obtained by a change in a position of the laser light detected by the optical system;

a laser light adjustment unit configured to adjust, when adjusting an optical axis of the laser light, a spot diameter of the laser light to be larger than the spot diameter when measuring the characteristics of the sample;

an imaging unit configured to capture an image of a range including a position of the probe when adjusting the optical axis of the laser light; and a display unit configured to display the image captured by the imaging unit.

With this, when adjusting the optical axis of the laser light, the spot diameter of the laser light is set to be larger than that when measuring the sample, which increases the probability that the spot of the laser light can be found in the captured image. Consequently, the user can perform the optical axis adjustment of the laser light while viewing the captured image.

A scanning type probe microscope according to another aspect of the present invention is provided with:

a cantilever provided on a tip end thereof with a probe;

an optical system configured to emit laser light to the cantilever and detect the laser light reflected by the cantilever;

a measurement unit configured to measure characteristics of a sample based on a displacement of the cantilever obtained by a change in a position of the laser light detected by the optical system;

a laser light adjustment unit configured to adjust, when adjusting an optical axis of the laser light, a spot diameter of the laser light to be larger than the spot diameter when measuring the characteristics of the sample;

an imaging unit configured to capture an image of a range including a position of the probe when adjusting the optical axis of the laser light;

an image processing unit configured to specify a position of a part or an entirety of the spot of the laser light in the image captured by the imaging unit; and an optical axis adjustment unit configured to adjust an optical axis of the laser light based on the specified position.

With this, when adjusting the optical axis of the laser light, the spot diameter of the laser light is set to be larger than that when measuring the sample. Therefore, by performing the image processing of the captured image, the position of the spot of the laser light can be specified in the captured image. Therefore, it is possible to automatically adjust the optical axis of the laser light based on the specified spot position of the laser light.

Preferably, the optical system includes a light source configured to emit laser light, a photodetector configured to detect the laser light, a first mirror configured to reflect the laser light emitted from the light source toward the cantilever, and a second mirror configured to reflect the laser light reflected by the cantilever toward the photodetector.

With this, in the configuration in which the optical system includes the light source, the photodetector, the first mirror, and the second mirror, it is possible to automatically adjust the light source of the laser light.

Preferably, the optical axis adjustment unit adjusts the optical axis of the laser light by moving the position of the light source based on the specified position.

With this, the optical axis of the laser light can be automatically adjusted by simply changing the position of the light source.

Preferably, the optical axis adjustment unit adjusts the optical axis of the laser light by moving the position of the cantilever based on the specified position.

With this, the optical axis of the laser light can be automatically adjusted by simply changing the position of the cantilever.

Preferably, the optical axis adjustment unit adjusts the optical axis of the laser light by moving the position of the first mirror based on the specified position.

With this, the optical axis of the laser light can be automatically adjusted by simply changing the position of the first mirror that reflects the laser light.

Preferably, the laser light adjustment unit adjusts intensity of the laser light when adjusting the optical axis of the laser light to be equal to or higher than a sensitivity limit of the imaging unit.

With this, it is possible to prevent the intensity of the laser light from becoming lower than the discernible sensitivity due to the excessively large spot of the beam of the laser light.

Preferably, the optical axis adjustment unit adjusts the optical axis of the laser light so that a position of the center of the spot of the laser light coincides with the position of a tip end of the cantilever in the image.

With this, the laser light is emitted to the tip end of the cantilever where the probe is attached. Therefore, it is possible to accurately detect the displacement of the cantilever due to the characteristics of the sample at the time of the measurement.

Preferably, after the adjustment, the laser light adjustment unit further adjusts the spot diameter of the laser light to be equal to the spot diameter when measuring the characteristics of the sample, and the optical axis adjustment unit adjusts the optical axis of the laser light such that the position of the center of the narrowed laser light coincides with the position of the tip end of the sample in the image.

With this, the optical axis of the laser light can be precisely adjusted. Preferably, the image processing unit specifies a position of the part or the entirety of the spot of the laser light based on a color of the pixel in the image.

With this, it is possible to locate the position of the spot of the laser light by finding the pixel of the color of the spot of the laser light from the image.

A control device for a scanning type probe microscope according to one aspect of the present invention controls a scanning probe microscope. The scanning probe microscope is provided with a cantilever provided on a tip end thereof with a probe, an optical system configured to emit laser light to the cantilever and detect the laser light reflected by the cantilever, a measurement unit configured to measure characteristics of a sample based on a displacement of the cantilever obtained by a change in a position of the laser light detected by the optical system, and an imaging unit configured to capture an image of a range including a position of the probe when adjusting the optical axis of the laser light. The control device includes a laser light adjustment unit configured to adjust, when adjusting an optical axis of the laser light, a spot diameter of the laser light to be larger than the spot diameter when measuring the characteristics of the sample, an imaging unit configured to capture an image of a range including a position of the probe when adjusting the optical axis of the laser light, an image processing unit configured to specify a position of a part or an entirety of the spot of the laser light in the image generated by the imaging unit, and an optical axis adjustment unit configured to adjust an optical axis of the laser light based on the specified position.

With this, when adjusting an optical axis of the laser light, a spot diameter of the laser light is adjusted to be larger than the spot diameter when measuring the characteristics of the sample. Therefore, it is possible to specify the spot position of the laser light in the captured image by performing the image processing of the captured image. The optical axis of the laser light can be automatically adjusted based on the specified spot position of the laser light.

Effects of the Invention

According to the present invention, the optical axis adjustment can be performed easily.

