JP2003502690A - Optical device - Google Patents

Abstract

(57) [Summary] An optical device for transmitting high-intensity light to a position remote from a light source includes a polychromatic non-laser light source (21) and an optical fiber means (12) for transmitting the light to the position. And an elliptical reflector (22) configured to focus light from the light source onto an input end of the optical fiber means (12). The open aperture of the elliptical reflector (22) is at least 100 times larger than the effective size of the light source (21). The light source (21) is preferably a xenon arc lamp, in particular a lamp of the "short arc" type. One important use of such a device is to send light of sufficient intensity to polymerize the adhesive to the photoactive tissue adhesive. There are also many other uses in the medical, chemical, and industrial fields.

Description

Detailed Description of the Invention

The present invention relates to an optical device, and more particularly, to a device for delivering high intensity light from a light source to a remote location. One important application of such devices is to deliver light to a photoactive tissue adhesive of sufficient intensity to cause polymerization of the adhesive. Another application of such a device is in photodynamic therapy (PDT), where light is used to excite pre-administered photosensitizers. Various other applications also exist in the medical, scientific and industrial fields.

Sealants and adhesives for joining living tissues in vivo are known. Such adhesives generally include a protein solution that crosslinks upon heating. By incorporating a photon-absorbing substance into the adhesive and applying light of sufficiently high light intensity to the adhesive,
Heat energy can be transferred to proteins. The amount of energy required to raise the temperature high enough to cure the adhesive requires the provision of multiple photons of radiation within the absorption spectrum of the photon absorbing material. Also, the dimensions of the light beam used in such applications must generally be very small. Until now, it has been necessary to use lasers, which are very intense monochromatic light sources, to meet these requirements.

The use of lasers is acceptable for some applications, but in some cases it is usually unsatisfactory due to the very high monochromaticity of such sources. Lasers are difficult to tune, and thus it may be difficult or impossible to precisely or properly tune the wavelength of the laser source to the absorption wavelength of the photon absorbing material.

White light sources have been used in other applications related to the delivery of light to remote locations. However, the light intensity achievable with such light sources has heretofore been severely limited and unsuitable for many applications.

[0005]   A device has been devised which overcomes or substantially mitigates the aforementioned drawbacks.

According to a first aspect of the invention, an optical device for delivering high intensity light to a location remote from a light source comprises a polychromatic non-laser light source and an optical fiber means for transmitting said light to said location. An elliptical reflector configured to focus light from the light source onto an input end of the optical fiber means, the open aperture of the elliptical reflector being at least the effective size of the light source. 100 times bigger.

The device of the invention is mainly advantageous in that the irradiance at the input end of the optical fiber means can be brought to very high levels by the use of elliptical reflectors. The use of polychromatic non-laser light sources is accompanied by other advantages such as lower cost, more compactness, safety and ease of maintenance. In addition, polychromatic light allows greater flexibility in applications. If desired, the appropriate wavelength bandwidth can be selected relatively easily. The intensity of the light introduced into the fiber optic means may be sufficient for applications where the fiber optic means forms part of an endoscopic device. Also, the device of the present invention may use particularly thin (small diameter) optical fiber means, such optical fiber means having a high degree of mechanical freedom, and thus applications where high degrees of freedom are advantageous ( It is particularly suitable for use in endoscopes).

The term “clear aperture” of a reflector means the maximum dimension of the aperture of the reflector (in the case of a reflector having a circular or partially circular cross section, its diameter).

The “effective size” of a light source means the largest physical dimension of the element or component of the light source from which light is generated. In the preferred case where the light source is an arc lamp, this is the size of the arc gap.

A variety of polychromatic light sources may be used in the practice of the invention provided they have the desired spectral range and sufficient light intensity. However, as mentioned above, the most preferred form of light source is an arc lamp, most preferably a xenon arc lamp,
In particular, they are so-called "short arc" type lamps. Such lamps have a continuous, nearly spectral line free output and high light intensity.

The arc lamp is preferably less than 0.6 mm, more preferably 0.2-0.5.
It has an arc gap in the range of mm, for example 0.4 mm. The output of the arc lamp is preferably in the range of 100 to 200W. Such a lamp can be used to easily produce a beam with suitable dimensions and sufficient power for surgical or other applications.

Light from a light source (most preferably a xenon arc lamp) is collected and focused by an elliptical reflector. The reflector should be shaped to collect an optimal amount of light energy in the 400-700 nm range of the spectrum and focus this light in one spot, and should be designed to minimize aberrations. To achieve this, the open aperture of the elliptical reflector is very large relative to the size of the arc gap. More specifically, the open aperture of the elliptical reflector is at least 100 times larger than the size of the arc gap, more preferably at least 200 times larger, eg 250 times larger.

In practice, the optimal shape of the elliptical reflector (ie the shape that maximizes the collection) can be determined by the geometry of the arc lamp electrode and the maximum acceptance angle of the fiber optic means. In general, the shape of the reflector is such that the magnification of the light intensity is optimized to maximize the light energy input to the fiber optic means and minimize aberrations. Most preferably, the arc lamp is mounted so that the arc is coaxial with the optical axis of the elliptical reflector. Light is emitted from such arcs over a range of solid angles limited by the geometry of the lamp electrodes, which typically have tapered ends. In particular, the shape of the electrode (preferably the cathode) closer to the optical fiber means affects the shape of the elliptical reflector. Generally, the tip of the cathode is tapered at an angle of about 50 ° with respect to the optical axis.

The light is preferably focused directly onto the input end of the optical fiber means by an elliptical reflector. This means that light is focused without the use of intervening refractive, reflective or diffractive optical elements. However, as described below,
It may be necessary or desirable to place more than one filter or the like in the optical path.

The light source (ie, the arc lamp in the preferred case) is preferably removably mounted in the device separately from the elliptical reflector. To facilitate this, the reflector is preferably provided with an opening into which the lamp can be inserted (or an elliptical reflector can be mounted around the lamp). Mounting the lamp and reflector separately has several advantages, in particular the lamp can be replaced or replaced without removing the reflector.

Arc lamps are essentially white light sources, and in many applications it may be necessary or desirable to limit the output beam to a particular range of wavelengths. A suitable range of wavelengths (bandwidth) can be selected by a filter inserted in the optical path. A "hot mirror" to remove low wavelengths and dissipate heat from the system
And a type of filter called a "cold mirror" can be included. In general, any filter that is sufficiently transparent in the wavelength band of interest and that is tolerant of large amounts of energy that should not be transmitted may be used. Dichroic filters are preferred. Light absorbing tinted glass filters may be used, but may not be suitable for many applications as they may not be able to absorb the relatively large amounts of energy that must be dissipated within the filter.

One example of an application where the output beam must be limited to a particular bandwidth is the activation of tissue adhesive. In this case, the lower wavelength limit of the bandwidth is generally chosen to protect against any undesired absorption by substances such as blood in contact with the tissue adhesive. This is because this absorption causes undesired heating of the target area. The upper bandwidth wavelength filters out infrared light radiation which can result in direct heating of the target area. The optimum bandwidth of radiation used in such applications depends on the absorption spectrum of the material to which the light is supplied. In one example where the adhesive incorporated methylene blue (which has a strong absorption at 620-670 nm), the bandwidth was typically around 100.
nm, centered at about 650 nm. In general, the bandwidth is most commonly 10
~ 200 nm. The output spectrum matches the absorption characteristics of the adhesive,
It may be within a single band or may include more than one band.

The optical fiber means are generally arranged such that their end plates are arranged at the exit face of the optical train, so that the output spot is focused on the end plates. The fiber is generally long enough to allow the light source to be placed at a convenient distance from the patient and is easily manipulatable by the user. Generally, the length of the fiber is 1-3 m,
For example, it is about 2.5 m.

The fiber diameter can be in the range of 0.01-1 mm or larger. For certain applications, such as intravascular irradiation, the fiber diameter is at the lower end of this range, typically about 0.2 mm.

To maximize the energy input to the optical fiber, the fiber should have NA = sin
It is preferable to have a relatively large numerical aperture such as θ, where θ is the half-angle of the acceptance cone at the end plate of the optical fiber. Numerical aperture 0.20-0
． It is preferably within the range of 52.

The optical fiber means may consist of a single fiber or a bundle of fibers. In the latter case, it is preferred that the input ends of the bundle of fibers are not glued together but fused together. This is because high light intensities can melt or destroy such adhesives, and such adhesives can absorb some of the light energy. Alternatively, the fiber bundle can be spliced to a short glass rod. If a bundle of fibers is used, the output end of the bundle of fibers can be trimmed to any desired shape, for example, to produce a beam of suitable shape for a particular application.

The fiber optic means is preferably contained within a protective outer sheath, most commonly made of a plastic material. In medical applications, it is desirable or necessary that the fiber optic means (as is true for some or all of the other components of the system) be sterilizable. In such cases, the protective outer sheath should consist of a material that can withstand sterilization.

Most preferably, the light emerging from the optical fiber means is projected onto the target by a handpiece adapted to be fitted at one end of the optical fiber and held by the user. Such handpieces preferably include a plurality of optical elements arranged to focus the output light beam at a distance to suit the particular application being performed. Further, the handpiece may shape the beam into a particular shape to suit the application. Such a shape may be a small diameter circular spot, a rectangle or any other desired shape.

Although described above primarily in the context of curing tissue adhesives, the device of the present invention may be used in a variety of other applications. Other medical applications include endoscopy and other applications where lasers or other powerful light sources are conventionally used, such as biostimulation, photodynamic therapy,
And hardening of dental materials. Other uses include curing materials such as semiconductor photoresists and industrial adhesives, as well as research applications in photochemistry, spectroscopy, and microscopy.

The present invention will be described in more detail with reference to the accompanying drawings, which are merely examples.

First, referring to FIG. 1, an apparatus for delivering polychromatic light to a site where two living tissues are joined is generally composed of a light source unit 10, an optical fiber tube 12, and a handpiece 14. This device is used to deliver light of sufficient intensity onto a tissue adhesive applied to the junction of two living tissues. In use, the surgeon should use the handpiece 1
Hold this 4 and use this device to illuminate the adhesive. The light source unit 10 is
A so-called “hot mirror” 15 and a filter pack 16 including a filter for selecting one or more wavelengths are provided in front of the input end of the optical fiber tube 12. The hot mirror 15 effectively blocks infrared radiation at approximately 780 to 1100 nm, while also blocking UV transmission below 380 nm. The filter pack 16 has the effect of removing wavelengths below 585 nm from the light beam. Therefore, the wavelength band of the transmitted radiation is approximately 585 to 700 nm. This band of wavelengths is suitable for use with tissue adhesives that absorb wavelengths in this region. An example of such an adhesive is an adhesive containing a coloring dye such as methylene blue that absorbs a wavelength of 620 to 670 nm.

FIG. 2 shows a light source used in the device of FIG. This light source consists of a xenon arc lamp 21 with a 0.4 mm gap at 150 W and an elliptical reflector 22. The lamp 21 extends through the central opening 23 of the reflector 22 and is arranged on the optical axis of the reflector 22 such that the cathode 24 of the lamp is arranged towards the input end of the fiber optic tube 12. To be done.

The tips of the cathode 24 and the anode 25 are tapered, and the arc gap is 0.
They are 0.4 mm apart from each other to be 4 mm. The tip of the cathode 24 is 5
It is tapered at an angle of 0 °, which limits the range of angles at which light is emitted from the arc. The reflector 22 has an open aperture D of 118 mm, which is large enough to trap all the light from the arc. Reflector 2
The shape of 2 is also represented by the maximum light receiving angle of the optical fiber tube 12 (31 ° in this case).

The lamp 21 is detachably attached to the light source unit 10 so that the lamp 21 can be removed without removing the reflector 22.

After passing through the filter pack 16, the light is focused on the end plate of the glass optical fiber contained within the optical fiber tube 12. The optical fiber itself has a diameter of approximately 1 mm and 0
． And a numerical aperture of 51. The optical fiber tube 12 has a protective outer sheath made of plastic material and has a total outer diameter of 6.5 mm and a length of 2.5 m.

The light is transmitted along the fiber optic tube 12 to the handpiece 14, by which the user directs the light onto the target area. The handpiece 14 includes a set of aspherical lenses (not shown) near its output end, which a few centimeters away from the end of the handpiece 14.
Focus the beam on a 1 mm diameter spot.

The optical device described above has the effect of transmitting high optical power density into the optical fiber. This intensity is such that the output light is converted to heat at the treatment site so that the tissue adhesive material polymerizes and joins the tissues. The output of this device is comparable to that of a laser device.

Thus, in use, the surgeon applies an adhesive to the tissues to be joined to bring them into contact. The surgeon then directs the light from the handpiece 14 onto the adhesive and operates the foot pedal to increase the light intensity to maximum intensity. Irradiation with high intensity light is continued for a time sufficient for the adhesive to cure. Sufficient irradiation of light may be indexed by a change in color (as described in WO 96/22797).

[Brief description of drawings]

[Figure 1]   1 is a schematic view of an apparatus according to the present invention.

2 is a side view (partial cross section) of a light source forming part of the apparatus of FIG.

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Claims (19)

[Claims] 1. An optical device for delivering high-intensity light to a position away from a light source, comprising a polychromatic non-laser light source, an optical fiber means for transmitting the light to the position, and a light source from the light source. An elliptical reflector configured to focus light onto the input end of the fiber optic means, the open aperture of the elliptical reflector being at least 100 of the effective size of the light source.
Twice as large as the optical device. 2. The apparatus of claim 1, wherein the light source is an arc lamp and the effective size of the light source is the size of the arc gap. 3. The arc lamp is a xenon arc lamp.
The device according to. 4. An apparatus according to claim 2 or 3, wherein the arc lamp has an arc gap of less than 0.6 mm. 5. The apparatus according to claim 4, wherein the arc lamp has an arc gap in the range of 0.2 to 0.5 mm. 6. The output of the arc lamp is in the range of 100 to 200 W,
The device according to any one of claims 2 to 5. 7. The apparatus according to claim 1, wherein the open aperture of the elliptical reflector is at least 200 times larger than the effective size of the light source. 8. The apparatus of claim 2, wherein the arc lamp is mounted to have an arc coaxial with the optical axis of the elliptical reflector. 9. A device according to claim 1, wherein the elliptical reflector focuses light directly onto the input end of the optical fiber means. 10. The apparatus of any one of claims 1-9, wherein the light source is removably mounted within the apparatus, separately from the elliptical reflector. 11. The reflector is provided with an opening through which the light source is inserted, or through which the elliptical reflector is mounted around the lamp. The apparatus according to item 10. 12. The method of claim 1, further comprising one or more filters inserted in the optical path between the light source and the fiber optic means to select a range of wavelengths.
11. The device according to any one of 11. 13. The apparatus of claim 12, wherein the range of wavelengths has a bandwidth of 10 nm to 200 nm. 14. The apparatus of claim 13, wherein the bandwidth is approximately 100 nm wide centered at 650 nm. 15. A device according to any one of claims 1 to 14, wherein the optical fiber means has a length of 1 to 3 m. 16. A device according to any one of claims 1 to 15, wherein the optical fiber means has a diameter in the range of 0.01 to 1 mm. 17. A device according to any one of the preceding claims, wherein the optical fiber means has a numerical aperture in the range 0.20 to 0.52. 18. A device according to claim 1, wherein the optical fiber means is housed in a protective sheath made of a plastic material. 19. The light emitted from the optical fiber means is projected onto a target by a handpiece adapted to be held by a user while being fitted to the end of the optical fiber means. 19. The device according to any one of 18.