Optical waveguides – Optical fiber bundle – Imaging
Reexamination Certificate
2000-06-26
2002-08-20
Sanghavi, Hemang (Department: 2874)
Optical waveguides
Optical fiber bundle
Imaging
C385S116000, C352S072000, C600S182000
Reexamination Certificate
active
06438302
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an endoscope system, and an illuminating device to be employed in the endoscope system.
It has been known that human tissues fluoresce when illuminated with excitation light. The wavelength range of the excitation light is a range of 380-480 nm, and the wavelength range of the fluorescent light emitted by the tissues is a range of 480-600 nm. The fluorescent light emitted by diseased tissues such as cancerous ones has less intensity than that emitted by normal tissues if they are illuminated with the predetermined excitation light. Therefore, conventionally, a fluorescent endoscope system utilizing-the above characteristics has been developed and used. Such an endoscope system has, as shown in
FIG. 4
, a fiber scope system
1
, an illuminating device
8
connected to the fiber scope
1
, and an image capturing device
3
.
The fiber scope
1
includes an insertion portion
11
to be inserted in a human cavity, an operation unit
12
connected to the insertion portion
11
. and a connecting tube
13
connected to the operation unit
12
. At the distal end side surface of the insertion portion
11
. three through openings are formed, one of which is used as a forceps outlet
14
a
, and an illumination lens
15
a
and an objective lens
16
a
are fitted in the other openings, respectively.
An end of the operation unit
12
is connected to the proximal end of the insertion portion
11
. An eyepiece optical system
16
c
is accommodated in the operation unit
12
. Inside the insertion portion
11
and the operation unit
12
, an image guide fiber bundle
16
b
(hereinafter referred to as an image guide) is inserted. The image guide
16
b
is arranged such that the tip end surface thereof faces the objective lens
16
a
, and the proximal end surface faces the eyepiece optical system
16
c.
An end of the connection tube
13
is connected to a side surface of the operation unit
12
, and the other end of the connection tube
13
is connected to the illuminating device
8
. Inside the insertion portion
11
, the operation unit
12
, and the connection tube
13
, a light guide fiber bundle
15
b
(hereinafter referred to as a light guide) is inserted.
The Illuminating device
8
is provided with a xenon lamp
81
, a reflector
82
, an infrared cut off filter
83
and a light source side band pass filter
84
. The xenon lamp
81
emits white light having a relatively large intensity. The reflector
82
is arranged such that the white light emitted by the xenon lamp
81
is reflected toward a light receiving surface of the light guide
15
b
as converging light. Between the xenon lamp
81
and the light receiving surface of the light guide
15
b
, the infrared cut out filter
83
, which prevents radiation of heat by removing Infrared component within the white light, and the light source side band pass filter
84
, which allows light having a predetermined wavelength range (e.g., 400 nm-450 nm) that corresponds to the wavelength range of an excitation light, are arranged.
Thus, the light emitted by the xenon lamp
81
and reflected by the reflector
82
enters the light guide
15
b
with the infrared components being removed by the infrared cut filter
83
, and the components other than the excitation light being removed by the band pass filter
84
.
The light conducted by the light guide
15
b
is emerged from a light emerging surface thereof. The light emerged form the light guide
15
b
is incident on the illumination lens
15
a
and emerged therefrom as a diverging excitation light. The excitation light Illuminates a wall of a human body cavity, thereby the illuminated portion of the body cavity fluoresces to emit fluorescent light. The fluorescent light emitted by the body cavity as well as the excitation light reflected by the body cavity is incident on the objective lens
16
a
. The objective lens
16
a
converges the incident light on the light receiving surface (i.e., the tip end surface) of the image guide
16
b
to form an image of the illuminated portion, which is transmitted to the eyepiece optical system through the image guide
16
b.
In the image capturing device
3
, an optical path along which the light emerged from the eyepiece optical system
16
c
is defined. The image capturing device
3
includes, along the optical path, a band pass filter
31
, a condenser lens
32
, an image intensifier
33
, an imaging optical system
34
and a camera head
35
.
The band pass filter
31
cuts off the reflected excitation light component so that only the fluorescent light component passes therethrough. The condenser lens
32
collects the light passed through the band pass filter
31
and converges the same to impinge on the image intensifier
33
. The image intensifier
33
intensifies the incident light. The imaging optical system
34
converges the intensified light to form an image on an image receiving surface of the camera head
35
. The camera head
35
converts the optical image formed on the image receiving surface into an electrical image (i.e., an electrical signal), and transmits the electrical signal to a camera control unit
4
(hereinafter referred to as CCU). The CCU
4
converts the electrical signal received from the camera head
35
into an image signal, and displays the image carried by the electrical signal on a monitor
5
.
Further to the above, the conventional fluorescent endoscope system is provided with a polychromator
6
, and a personal computer
7
connected to the polychromator
6
. The polychromator
6
includes a light guide probe
6
a
. The polychromator
6
detects intensity of light incident on the tip end of the light guide probe
6
a
on wavelength basis.
The light guide probe
6
a
is inserted from a forceps inlet opened on the operation unit
12
and inserted through the fiber scope
1
, the tip end of the light guide probe
6
a
being protruded out of the forceps outlet
14
a
of the insertion portion
11
.
The polychromator
6
detects the intensity of the fluorescent light conducted by the light guide probe
6
a
on wavelength basis, converts the same into electrical signals, and outputs to the personal computer
7
. The personal computer
7
displays a graph showing an intensity distribution of the fluorescent light on wavelength basis.
According to the conventional fluorescent endoscope system, the illuminating device
8
is constituted such that the white light is incident on the band pass filter
84
to obtain the excitation light. However, it is impossible to completely remove the components other than the excitation light component from the white light with the band pass filter
84
. Therefore, in the conventional fluorescent endoscope system, the light components other than the excitation light component affect the image to be observed.
Alternative to the above-described illuminating device
8
, an illuminating device employing a laser light source can be employed. Since the laser is superior in terms of monochromatism, the band pass filter
84
and the like are unnecessary. However, in order to obtain a sufficient intensity as the excitation light, the light source needs to be a large device such as a gas laser device. Further, such a laser device requires a relatively long idling period before it starts emitting light, the light source should be ready in advance, which is troublesome. Furthermore, when the gas laser device is used, an initial cost as well as a maintenance cost becomes relatively expensive.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide an improved endoscope system employing an illuminating device which is superior in monochromatism, and can be used simply and quickly.
For the above object, according to the invention, there is provided an illuminating device for an endoscope system. The illuminating device emits light toward a light receiving surface of an optical fiber bundle. The light incident on the light receiving surface of the optical fiber bundle is emitted from a light emitting surface thereof for illuminating an
Furusawa Koichi
Utsui Tetsuya
Asahi Kogaku Kogyo Kabushiki Kaisha
Greenblum & Bernstein P.L.C.
Rojas, Jr. Omar
Sanghavi Hemang
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