Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2001-05-21
2003-09-09
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S234000, C250S306000
Reexamination Certificate
active
06617569
ABSTRACT:
This application claims the priorities of Japanese Patent Application No. 2000-158560 filed on May 29, 2000 and Japanese Patent Application No. 2000-166238 filed on Jun. 2, 2000, which are incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to a probe opening forming apparatus and a near-field optical microscope using the probe opening forming apparatus, and more particularly to an improvement of a method of controlling the size of an opening of a probe.
BACKGROUND OF THE INVENTION
In general, a microscope can observe a very fine portion without destruction in a non-contact with a sample and can further analyze a component of an observation object as well as a shape and a structure thereof by connecting a spectrum analyzer or the like, and has been applied to various fields.
However, a general optical microscope cannot observe a smaller thing than a wavelength of a light and has a resolution thereof limited.
On the other hand, in an electron microscope, the resolution can be enhanced greatly but it is very hard to carry out an operation in the air or in a solution. Thus, a high resolution microscope such as the electron microscope has not been always satisfactory particularly in the field in which a biological sample is to be treated.
On the other hand, a near-field optical microscope based on a different principle from the general optical microscope or the electron microscope has recently been developed and an application thereof has been expected.
The near-field optical microscope serves to detect a so-called evanescent light.
More specifically, in
FIG. 1
, a near-field optical microscope
10
has a very small sample
12
to be measured which is put on a flat substrate
14
. When an excited light
18
is incident from a light source
16
at such an angle that total reflection is carried out over the back face of the substrate
14
, all propagated lights are reflected. However, a surface wave referred to as an evanescent light
20
is generated in the vicinity of the surfaces of the substrate
14
and the sample
12
. The surface wave is locally present in a region at a distance within the wavelength of the light around the surface of an object.
A probe
22
having a sharp end is inserted in the field of the evanescent light
20
to scatter the evanescent light
20
. A part of a scattered light
21
enters the probe
22
and is guided to a detector
24
, and data processing is carried out through a computer
26
. Consequently, a distance between the tip portion of the probe
22
and the sample
12
can be grasped.
Accordingly, a stage
30
is moved through the computer
26
and a stage controller
28
and a vertical distance between the tip portion of the probe
22
and the sample
12
is controlled such that the scattered light
21
has a constant intensity, and a surface of the sample
12
which is to be measured is scanned. Consequently, it is possible to accurately grasp the concavo-convex portions of the sample
12
in a non-contact with the sample
12
.
In addition, the tip of the probe
22
is only present in the field of the evanescent light
20
and does not come in contact with the object itself to be measured. Therefore, it is possible to observe a thing having a smaller value than the wavelength of the light without destruction in a non-contact with the sample
12
.
As shown in
FIG. 2
, the probe
22
includes a core
32
constituted by a dielectric having a light transmittance and a mask
34
constituted by a metal thin film bonded on the surface of the core
32
through evaporation or the like.
An opening
36
is formed in the tip portion of the mask
34
and a tip portion
32
a
of the core
32
is appeared from the opening
36
.
As a method of forming the opening of the probe, for example, the tip of the core of an optical fiber is sharpened by a selective chemical etching method, a method of heating and stretching the tip or the like.
In vacuum, a metal is heated and evaporated, and is bonded as a thin film to the surface of the sharpened probe, thereby forming a mask of a metal thin film or the like.
Next, the mask of the tip portion is removed through etching method, focused ion beam (FIB) or the like, for example. Consequently, the opening
36
is formed.
The probe
22
thus formed is attached to a head
31
of the near-field optical microscope
10
to carry out the near-field optical measurement described above.
In order to enhance the resolution of the near-field optical microscope, it is necessary to form an opening having a desired size in the tip of the probe with high reproducibility.
However, the mechanical dimension of the opening can be controlled but an optical characteristic such as a light transmittance cannot be controlled during formation by using the opening forming method described above. Consequently, the optical characteristic such as the light transmittance of the opening to which importance should be attached for performance has not been considered.
For this reason, when the fabricated probe is actually attached to the near-field optical microscope to carry out the measurement, the measurement cannot be carried out well in some cases.
Consequently, it has been greatly desirable that a technique for forming an opening having a desired size in the tip of the probe with high reproducibility should be developed in consideration of the optical characteristic such as the light transmittance. However, there has not been a proper technique capable of solving the problem.
SUMMARY OF THE INVENTION
In consideration of the above-mentioned problems of the conventional art, it is an object of the present invention to provide a probe opening forming apparatus capable of easily forming an opening having a more desirable size and a near-field optical microscope using the probe opening forming apparatus.
For achieving the above-mentioned object, the probe opening forming apparatus in accordance with the present invention is a probe opening forming apparatus for opening a mask of a tip portion of a probe with a desirable size, comprising a core constituted by a material having a light transmittance and a mask formed on the core and constituted by a material having a ductility and a light shielding property; the probe opening forming apparatus comprising a light source, a light detecting means, a pressing means, a storage means, a calculating means, and a pressing control means.
Here, the light source causes a light to be incident in the probe.
The light detecting means detects a quantity of a light transmitted from the tip portion of the probe through a light of the light source, which is on contact with the tip portion of the probe.
The pressing means presses the tip portion of the probe against the light detecting means in a direction of an optical axis.
The storage means previously stores information about relation of the quantity of the light transmitted from the tip portion of the probe and the size of the opening.
The calculating means obtains the value of the light quantity for obtaining an opening having a desirable size based on the information about the relation of the quantity of the light transmitted from the tip portion of the probe and the size of the opening which is stored in the storage means.
The pressing control means controls the press of the tip portion of the probe against the light detecting means in the direction of the optical axis through the pressing means such that a value of a light quantity detected by the light detecting means is equal to the value of the light quantity calculated from the calculating means.
The core constituted by a material having a light transmittance is formed of an optical fiber material such as quartz, a semiconductor, CaF
2
, chalcogenide or the like.
Moreover, the mask constituted by a material having a ductility and a light shielding property is formed of a metal thin film to be used for a mirror, for example, gold, aluminum, silver, chromium or titanium which is formed on the core through evaporation or the like.
Furthermore, the mask formed in the tip portion
Inoue Tsutomu
Mononobe Shuji
Narita Yoshihito
Ohtsu Motoichi
Saiki Toshiharu
Jasco Corporation
Le Que T.
Luu Thanh X.
Snider Ronald R.
Snider & Associates
LandOfFree
Probe opening forming apparatus and near-field optical... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Probe opening forming apparatus and near-field optical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Probe opening forming apparatus and near-field optical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3074540