Patent Description:
An OCT device is a device capable of taking tomography images of a human body using interference of light in the infrared band. At the initial stage of technology development, it was possible to obtain images of several frames per second by changing the optical path mechanically. Nowadays, tomography images of several hundred frames per second can be taken by employing a three-dimensional OCT technique that makes use of a wavelength tunable laser and a high-speed digitizer.

<FIG> shows a conventional OCT device and a microscope equipped with the OCT device. The conventional OCT device captures tomography images with an interference signal of the signal light and the reference light by bypassing the light of an object incident on the microscope.

However, since the OCT device of the type shown in <FIG> requires a portion (A) (a beam splitter or the like) of the OCT device to be interposed between the main body of the microscope or the like and the objective lens (B) in order to bypass the signal light. This raises a problem that installation of the OCT device is difficult and that the alignment of precision equipment such as a microscope or the like is disturbed.

<FIG> shows an endoscope in which an OCT device is integrally formed. The endoscope in which the OCT device is integrally formed therewith can simultaneously perform the functions of the endoscope and the OCT device because a transducer and a optical fiber for a light source are formed within the endoscope.

However, the OCT device of the type shown in <FIG> suffers from a problem that all existing conventional endoscopes should be discarded and replaced by new ones, which leads to excessive waste of resources. Examples of OCT devices according to the prior art are known from <CIT>, <CIT>, <CIT> and <CIT>. <CIT> discloses the features of the preamble of claim <NUM> and is considered to represent the most relevant prior art.

Embodiments of the present disclosure solve the problems mentioned above. In some embodiments, a removable OCT device is capable of being easily installed and removed and minimizing a change of an existing optical device such as a microscope.

A removable OCT device according to one example not falling under the scope of claim <NUM> includes: a tunable laser configured to emit light to a light output side of an optical device by tuning a wavelength of the light; a first beam splitter installed on a path of the light emitted from the tunable laser; and a reference mirror installed on a path of the light that has passed through the first beam splitter, wherein the removable OCT device is mounted at the light output side of the optical device.

The removable OCT device adapted to be used in state in which the removable OCT device is mounted on the light output side of an existing optical device. It is therefore possible to remarkably reduce the risk of misalignment or damage of the existing optical device.

Furthermore, the removable OCT device may be mounted while maintaining the existing optical device. It is therefore possible to use the existing optical device without having to discard the same.

Moreover, the removable OCT device may be easily attached and detached. It is therefore possible to use the OCT device by installing the same in one or more optical devices.

A removable OCT device not falling under the scope of claim <NUM> will now be described in detail with reference to the accompanying drawings.

<FIG> is a structural diagram of a removable OCT device according to a first example not falling under the scope of claim <NUM>. The removable OCT device according to the present embodiment is a device mounted at the light output side of an optical device such as an endoscope, a microscope or the like (at the same side as an ocular lens) and simultaneously acquires a visible light image and an OCT image. The removable OCT device includes a tunable laser <NUM>, a first beam splitter <NUM>, a reference mirror <NUM>, a second beam splitter <NUM>, a band pass filter unit <NUM> and an image detector unit <NUM>. The removable OCT device may further include a vibration compensator <NUM> and an image processor (not shown).

The tunable laser <NUM> is a component which emits light to the light output side while tuning the wavelength so that the human body tissue can be taken tomographically by depth, and which makes sure that an infrared ray is reflected from a measurement target object (a human body or the like) to be measured by an optical device (that the light incident on the light output side reaches the measurement target object through the optical device). In some embodiments, the wavelength is tuned in the infrared region of <NUM> to <NUM>. As the wavelength grows longer, the depth of infiltration of the light into the human body tissue becomes deeper. Thus, by emitting light while changing the wavelength of the light from a short wavelength to a long wavelength, it is possible to acquire stereoscopic interference signals from the surface of the human body tissue to a predetermined depth. An OCT can be implemented by image-processing the interference signals. The tunable laser <NUM> may further include an LED, a lamp or the like, which covers a visible ray region, so that the tunable laser <NUM> can provide a visible ray when the amount of the visible ray emitted from the measurement target object is deficient.

The first beam splitter <NUM> is a component which generates a reference light (light for setting a phase reference plane) by allowing a portion of the light emitted from the tunable laser <NUM> to pass through the first beam splitter <NUM> and to move toward the reference mirror <NUM>, and generates a signal light (a light reflected or emitted from the measurement target object and containing information of the measurement target object) by reflecting a portion of the light emitted from the tunable laser <NUM> and allowing the light to move toward the light output side. The first beam splitter <NUM> is configured to reflect the reference light reflected from the reference mirror <NUM> and is configured to allow the signal light emitted from the light output side to pass through the first beam splitter <NUM> and to move toward the second beam splitter <NUM>. Information on the measurement target object can be obtained by causing the reference light and the signal light, which are generated by the first beam splitter <NUM> in this way, to interfere with each other.

The reference mirror <NUM> is a component which reflects the light passed through the first beam splitter <NUM> and generates a reference light, namely a light to be compared with phase-shifted signal light.

The second beam splitter <NUM> is a component which allows a portion of the light emitted from the light output side and the light emitted from the reference mirror <NUM> to pass through the second beam splitter <NUM> while it reflects the other portion to divide the optical path into two. Since the second beam splitter <NUM> is installed on an optical path of the light emitted from the light output side and passed through the first beam splitter <NUM>, the reference light and the signal light are incident on the second beam splitter <NUM>. The removable OCT device according to the present embodiment is configured to simultaneously pass a visible ray of a typical optical device and an infrared ray emitted by the tunable laser <NUM>. Thus, the removable OCT device includes an infrared ray image detector <NUM> and a visible light image detector <NUM> in order to separately take an image of the visible ray and the infrared ray. The second beam splitter <NUM> splits the light to be incident on the infrared image detector <NUM> and the visible light image detector <NUM>.

The band pass filter unit <NUM> is a component which filters the light to be incident on the infrared image detector <NUM> and the visible light image detector <NUM>. The band pass filter unit <NUM> may include an infrared band pass filter <NUM> installed on a path of one of the light beams split in the second beam splitter <NUM> and may further include a visible ray band pass filter <NUM> installed on a path of the other of the light beams split in the second beam splitter <NUM>. In the removable OCT device according to the present disclosure, the infrared image detector <NUM> has to receive only an electromagnetic wave of an infrared band as a signal. Thus, it is necessary to provide the infrared band pass filter <NUM> which passes the light of an infrared band. The visible ray band pass filter <NUM> is an optional component. In general, a CCD or CMOS image detector is sufficient to take visible light images. Thus, the visible ray band pass filter <NUM> may be provided when one wishes to enhance the purity of a visible light image by removing the light in the infrared band.

The image detector unit <NUM> may include an infrared image detector <NUM> and a visible light image detector <NUM>. On the basis of a travel direction of light, the infrared image detector <NUM> is installed behind the infrared band pass filter <NUM>, and the visible light image detector <NUM> is installed behind the second beam splitter <NUM> or the visible ray band pass filter <NUM>. In this regard, the rear side of the second beam splitter <NUM> refers to a travel path of the light other than the light which is separated by the first beam splitter <NUM> and is incident on the infrared image detector <NUM>.

The infrared image detector <NUM> has to take infrared images in a wavelength range of <NUM> to <NUM>. Thus, different types of image detectors are used depending on the wavelength range. Specifically, in the wavelength range of <NUM> to <NUM>, a typical CCD or CMOS image detector like the visible light image detector <NUM> may be used. However, since the typical CCD or CMOS image detector cannot detect an infrared ray of a wavelength of <NUM> or more, an InGaAs image detector is used. The visible light image detector <NUM> is an image detector used in a typical digital camera. A CCD or CMOS image detector is used as the visible light image detector <NUM>.

By providing a plurality of infrared ray image detectors <NUM>, it is possible to improve the quality of an OCT image. For example, when images are taken by installing two infrared ray image detectors <NUM> and synchronizing the image-taking timings thereof, it is possible to obtain two-fold images per unit time and to obtain OCT images having a high quality. When one wishes to obtain images of the same quality, it is possible to shorten the image-taking time by one half. Thus, the images are less susceptible to vibration and are somewhat free from the restrictions in the performance of the vibration compensator <NUM>.

The visible light image detector <NUM> may be an ocular lens. Since the human eyes may be regarded as one kind of the visible light image detector <NUM>, it is possible to implement an OCT device capable of taking infrared images with the infrared image detector <NUM> while seeing visible light images through an ocular lens. In this case, the human eyes serve as the visible ray band pass filter <NUM>. Thus, by removing the visible ray band pass filter <NUM>, it is possible to simplify the configuration of the OCT device.

The vibration compensator <NUM> is a component which compensates the vibration of the lens or the image detector unit <NUM>. The vibration compensator <NUM> may be an actuator (of hardware type) which mechanically compensates the vibration of the lens or the image detector unit <NUM> by measuring the vibration, or may be a processor (of software type) which compensates the vibration through image correction by matching the measured images. In the removable OCT device according to the present disclosure, the vibration compensation is needed for the following reason. Due to the characteristics of the OCT device, a plurality of images is taken within a short period of time while tuning the wavelength (namely, while changing the image-taking depth). At this time, if vibration or position shift occurs, an error may be generated in a stereoscopic image. The hardware type vibration compensator <NUM> is configured to physically cancel the actual vibration. The software type vibration compensator <NUM> is configured to compensate the error, which is generated in the image due to the vibration, through an image processing process.

The image processor (not shown) is a component which is connected to the image detector unit <NUM> and configured to process the visible light images and the infrared images acquired in the image detector unit <NUM>. Specific forms of the image processor include a field programmable gate array (FPGA), a digital signal processor (DSP), an ARM, and the like.

<FIG> is a structural diagram of a removable OCT device according to an embodiment of the present invention. The removable OCT device according to the present disclosure is mounted to the light the output side of a binocular optical device. The removable OCT device includes a tunable laser <NUM>, a pair of first beam splitters <NUM>, a reference mirror <NUM>, a pair of second beam splitters <NUM>, a pair of band pass filter units <NUM> and a pair of image detector units <NUM>. The removable OCT device may further include a vibration compensator <NUM> and an image processor. It can be said that the removable OCT device according to this embodiment of the invention is configured to be binocular, namely as a stereo system, by combining, in parallel, two removable OCT devices according to the first embodiment of the present disclosure. Accordingly, the removable OCT device according to the second embodiment of the present disclosure is useful in a device such as a microscope.

In order to take images by separating an infrared ray and a visible ray, the first beam splitters <NUM>, the second beam splitters <NUM>, the band pass filter units <NUM> and the image detector units <NUM> are respectively provided in a pair. The tunable laser <NUM> may be provided in a pair. Since it is desirable to irradiate the same light on an object, it is preferred that there is provided only one tunable laser <NUM>. Furthermore, a pair of reference mirrors <NUM> may be provided and may be respectively installed at the rear side of the first beam splitters <NUM>. Alternatively, one double-sided mirror may be installed as the reference mirror <NUM>. A pair of vibration compensators <NUM> and a pair of image processors may be provided, one in each of the image detector units <NUM>. Alternatively, one vibration compensator <NUM> and one image processor may be provided in the image detector units <NUM> as a whole.

Claim 1:
A binocular OCT device (<NUM>), comprising:
a tunable laser (<NUM>) configured to emit light as a tuned wavelength of the light;
a first beam splitter (<NUM>) installed on a path of the light emitted from the tunable laser; and
a reference mirror (<NUM>) installed on a path of the light that has passed through the first beam splitter (<NUM>),
wherein one side of the OCT device (<NUM>) is configured to be mounted at a light output side of the optical device where an ocular lens is located so that light reflected by the first beam splitter (<NUM>) is irradiated to the ocular lens of the optical device, and the other sides of the OCT device (<NUM>) are not configured to be mounted to the optical device characterized in that the binocular OCT device is configured to be attachable to or detachable from a light output side of an optical device for dual eyes and configured by combining, in parallel, two OCT devices.