Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1999-01-14
2001-01-09
Phan, James (Department: 2872)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C198S457040, C198S457040, C198S457040, C198S457040, C198S457040, C198S368000
Reexamination Certificate
active
06172789
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a light scanning type confocal optical device, which scans light emitted from a light source over the surface of an object, and detects light reflected from the surface or fluorescence, and also relates to a light scanning device applied to the optical device.
In recent years, the light scanning type confocal optical microscope has been known as means for minutely observing living tissue or the surface or the inside of cells. The confocal optical microscope has a resolving power exceeding that of an ordinary optical system and, in addition, can obtain a three-dimensional image. However, an ordinary confocal optical microscope has a large optical system, and can not practicably be inserted into the living body. Thus, in general, living tissue is removed from the body in order for the tissue to be observed with the ordinary confocal optical microscope.
In order to overcome this disadvantage, a smaller optical system of a light scanning type micro-confocal microscope is disclosed in the literature “Micromachined scanning confocal optical microscope” (OPTIC LETTERS, Vol. 21, No 10, May, 1996) or U.S. Pat. No. 5,742,419.
The literature suggests the possibility with which a three-dimensional image could be obtained in real time. To be more specific, the above light scanning type micro-confocal microscope, as shown in
FIG. 8
, comprises a light source
1
, a light transmitting section
2
, a light detecting section
3
, a light scanning section
4
, and a processing section
5
. The light transmitting section
2
has a single mode fiber. The light scanning section
4
is inserted into the living body through an endoscope. By virtue of this, a three-dimensional image of the inside of the living body could be obtained in real time.
FIG. 9
shows the structure of the light scanning section
4
. In the light scanning section
4
, a laser light is emitted from the light source
1
, and transmitted through the single mode fiber
10
. Then, it is reflected by a reflection surface
11
, and deflected in an X direction by an electrostatic mirror
12
for scanning light in the X direction. Thereafter, it is totally reflected by a reflection portion
14
, deflected in a Y direction by an electrostatic mirror
13
for scanning light in the Y direction, and then converged onto an object surface
16
by a diffraction lens
15
.
An end face of the single mode fiber
10
has a conjugate relationship with the object surface
16
. Accordingly, the light reflected from the object surface
16
turns back on the above optical path, and converges on the end face of the single mode fiber
10
. To be more specific, the light reflected from the object surface
16
is incident on the diffraction lens
15
, and thereafter reflected successively by the electrostatic mirror
13
, the reflection portion
14
, the electrostatic mirror
12
, and the reflection surface
11
in that order. Then, it is converged on the end face of the single mode fiber
10
by a converging function of the diffraction lens
15
. The converged light is transmitted through the single mode fiber
10
of the light transmitting section
2
, and detected by the light detecting section
3
.
The above optical system composes a confocal optical system, since the end face of the core of the single mode fiber
10
functions as a pinhole. Thus, scattered light from that portion of the object surface
16
which excludes a convergence point is sufficiently weak in intensity at the end face of the fiber
10
, and hardly detected by the light detecting section
3
.
Therefore, the above optical system has high resolution in a horizontal direction (XY direction) of the object surface
16
and a depth direction (Z direction) of the object surface
16
, as compared with the ordinary optical system. In other words, it has higher longitudinal and transverse resolving powers than the ordinary optical system.
The above light scanning type micro-confocal optical microscope has a lower resolving power than the ordinary confocal optical microscope; however, its resolving power is sufficient for diagnosis involving observation of an internal organ or the like. In addition, the micro-confocal optical microscope has a considerably compact structure.
In insertion of such a micro-confocal optical microscope into the living body through the endoscope to observe the inside of the body, its view direction obliquely crosses its insertion direction. Accordingly, it is difficult to accurately move the object surface
16
in the Z direction only. In other words, the above micro-confocal microscope has bad observational operability.
Furthermore, the conventional micro-confocal microscope uses two reflection surfaces
11
and
14
and two one-dimensional scanning mirrors
12
and
13
, in order to achieve two-dimensional scanning. However, use of such a large number of reflection surfaces causes attenuation of light due to reflection performed between the large number of surfaces, thus lowering the detection sensitivity.
BRIEF SUMMARY OF THE INVENTION
The present invention has been made to overcome the above disadvantages. An object of the invention is to provide a light scanning type compact confocal optical device, which has the view direction coincident with the insertion direction, thus improving the operability.
Another object of the invention is to provide a light scanning device, which allows realization of such a compact confocal optical system.
Still another object of the present invention is to provide a light scanning type confocal optical device or light scanning device, which has a small number of reflection surfaces, such that detection sensitivity is improved.
Additional objects and advantages of the invention will be set forth in the specification which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized by means of the instrumentalities and combinations particularly pointed out hereinafter.
REFERENCES:
patent: 5159495 (1992-10-01), Hamblen
patent: 5546214 (1996-08-01), Black et al.
patent: 5742419 (1998-04-01), Dickenshetts et al.
Dickensheets David L.
Kino Gordon S.
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Phan James
The Board of Trustees of the Leland Stanford Junior University
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