Optical waveguides – Optical fiber bundle – Imaging
Reexamination Certificate
2002-04-26
2004-06-01
Ullah, Akm Enayet (Department: 2874)
Optical waveguides
Optical fiber bundle
Imaging
C385S115000, C385S117000, C385S118000, C385S119000
Reexamination Certificate
active
06744957
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image fiber imaging apparatus comprising an image guide fiber bundle, such as a fiber scope, having a receiving end and a transmitting end, for receiving an image of an object at the receiving end and transmitting through and outputting the image at the transmitting end, an imaging device for picking up the image transmitted and outputted by the image guide fiber bundle, and a display unit for displaying the image picked up by the imaging device.
2. Description of the Related Art
In recent years, there are provided a wide variety of image fiber imaging apparatuses each of which comprising an image guide fiber bundle such as, for example, a fiber scope, having a receiving end and a transmitting end, for receiving an image of an object placed at the receiving end, and transmitting and outputting the image at the transmitting end, a solid-state imaging device for picking up the image transmitted through and outputted by the image guide fiber bundle, and a display unit for displaying the image picked up by the solid-state imaging device. The image guide fiber bundle includes a plurality of optical fibers regularly arranged in a certain manner. The image includes a plurality of image portions. The image portions collectively forming the image received by the image guide fiber bundle at the receiving end respectively enter into optical fibers collectively forming the image guide fiber bundle. More specifically, each of the optical fibers has core and clad portions. The core portion is an inner, light-guiding part of the optical fiber and the clad portion is a part surrounding the core portion. An image portion received by the image guide fiber bundle enters the core portion of an optical fiber at an angle. The fact that the refractive index of the core portion is higher than that of the clad portion leads to the fact that an image portion that enters the core portion at an angle can reflect off the boundary between the core and clad portions and propagate down the length of the optical fiber.
The core and clad portions in the regularly arranged optical fibers, however, generate dark and bright patterns in light passing through the optical fibers, thereby causing the image guide fiber bundle to output the image containing the dark and bright pattern noises at the transmitting end. The dark and bright pattern noises thus outputted will result in mesh patterns appeared in the display unit. Furthermore, the solid-state imaging device includes a plurality of light receiving elements regularly arranged in a certain manner. The regularly arranged light receiving elements interfere with the image containing the dark and bright pattern noises transmitted through and outputted at the transmitting end of the image guide fiber bundle, thereby causing Moire patterns appeared in the display unit.
Up until now, there have been proposed a wide variety of image fiber imaging apparatuses each comprising an optical lowpass filter between the image guide fiber bundle and the solid-state imaging device, in order to reduce the dark and bright patterns and Moire patterns appeared in the display unit. One typical type of such image fiber imaging apparatus is disclosed in Japanese Patent Application Laid-Open Publication No. 136813/1990.
Referring to
FIG. 4
of the drawing, there is shown a conventional image fiber imaging apparatus. The conventional image fiber imaging apparatus is shown in
FIG. 4
as comprising a fiber scope
12
, an optical coupler
13
, an optical lowpass filter
14
, a solid-state imaging device
2
, a camera control unit
3
, and a television monitor
5
. The fiber scope
12
includes a plurality of optical fibers
1
. The fiber scope
12
including a plurality of optical fibers
1
is adapted to receive and transmit an image of an object. The optical lowpass filter
14
is adapted to filter the image transmitted by the fiber scope
12
by compressing high frequency components in the image. The optical coupler
13
is placed between the fiber scope
12
and the optical lowpass filter
14
and adapted to optically couple the fiber scope
12
with the optical lowpass filter
14
in an appropriate manner. The solid-state imaging device
2
is adapted to pick up and convert the image filtered by the optical lowpass filter
14
into an image signal. The camera control unit
3
and the television monitor
5
are adapted to display the image signal thus picked up and converted by the solid-state imaging device
2
.
The aforesaid conventional image fiber imaging apparatus comprising an image guide fiber bundle
12
, however, encounters a drawback that the conventional image fiber imaging apparatus is i to be equipped with an optical lowpass filter
14
, which is expensive and large in size, in order to reduce the dark and bright patterns and Moire patterns appeared in the display unit. Furthermore, the optical lowpass filter
14
is required to be selected in accordance with the line thickness and density of the image guide fiber bundle
12
.
In the conventional image fiber imaging apparatus, the image guide fiber bundle
12
is replaceable with a relay lens. The conventional fiber imaging apparatus comprising a relay lens in place of the image guide fiber bundle
12
encounters another drawback that the optical lowpass filter
14
has frequency characteristics appropriate for reducing the dark and bright patterns and Moire patterns caused by image guide fiber bundle
12
and the solid-state imaging device
2
originally equipped, thereby impossible to reduce the dark and bright patterns and Moire patterns appeared in the display unit
5
and achieve a high resolution unless the optical lowpass filter
14
is replaced or adjusted in accordance with the frequency characteristics of the relay lens newly replaced.
The present invention contemplates resolution of such problems.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an image fiber imaging apparatus comprising an image guide fiber bundle, which achieves a high resolution, effectively reducing the dark and bright patterns and Moire patterns appeared in a display and eliminates the needs of an optical lowpass filter, which is expensive and large in size, thereby making it possible to manufacture an high-performance image fiber imaging apparatus simple in structure at a low cost.
It is another object of the present invention to provide an image fiber imaging apparatus comprising a relay lens in place of an image guide fiber bundle, which achieves a high resolution, effectively reducing the dark and bright patterns and Moire patterns appeared in a display and eliminates the needs of an optical lowpass filter, which is expensive and large in size, thereby making it possible to manufacture an high-performance image fiber imaging apparatus simple in structure at a low cost.
In accordance with a first aspect of the present invention, there is provided an image fiber imaging apparatus comprising: an image guide fiber bundle having a plurality of optical fibers, a receiving end, at which one ends of the optical fibers are arranged, and a transmitting end, at which other ends of the optical fibers are arranged, the receiving end being directed to an object to receive an image of the object, the optical fibers transmitting the image received at the receiving end to the transmitting end, the image including a plurality of image portions, each corresponding to one of the optical fibers; a solid-state imaging device arranged at the transmitting end of the image guide fiber bundle for converting the image including a plurality of image portions transmitted by the optical fibers of the image guide fiber bundle into an image signal; an electrical spatial filter for filtering the image signal converted by the solid-state imaging device to output a filtered image signal; and a display unit for displaying the filtered image signal outputted by the electrical spatial filter.
The aforesaid electrical spatial filter may include: a
Kobayashi Katsuhiro
Takenaga Yuichi
Pearne & Gordon LLP
Petkovsek Daniel
Ullah Akm Enayet
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