JP6886432B2 - Fiber Optic Beam Directional Systems and Equipment - Google Patents

Description

The present invention generally relates to the field of optics, and more specifically to the field of lenses used with optical fibers.

In optical analysis such as an interference measurement method, it is necessary to deliver light to a target sample (sample of interest) and to collect a part of the light returned from the sample. Many light sources and photoanalyzers are usually located away from the sample of interest due to their size and complexity. This is especially noticeable when the target sample is an internal part of a large object, such as a biological tissue in vivo. One method of optically analyzing the internal part is to use a thin optical fiber to guide the light from a remote light source to the sample. Since the optical fiber has a small cross section, it has little influence on the normal function of the sample. An example of such a method is to analyze a luminal organ such as a blood vessel using a fiber optic catheter, one end connected to an extracorporeal light source and the other end inserted into the blood vessel.

A major obstacle to the optical analysis of internal regions such as lumens is the design and low cost production of small optical devices for focusing or collimating light. Many types of optical analysis, such as imaging and spectroscopy, require that the light incident on the sample be focused or substantially collimated at a particular distance. Since the light emitted from the tip of a standard optical fiber diverges quickly, it is possible to connect a small optical system to the optical fiber to provide focusing or collimating functions. In addition, it is often desirable to analyze sample locations that do not directly coincide with the optical axis of the optical fiber, such as analysis of the lumen wall of small blood vessels. In such situations, in addition to the means for focusing or collimating the light emitted from the tip of the optical fiber, means for substantially changing the direction of the light are used.

So far, many methods have been described for producing small optical systems suitable for mounting on optical fibers that provide some of the functions described above. Generally, these methods are one of three methods: 1) using a graded index (GRIN) fiber portion, 2) molding the tip of the fiber directly into a lens, and 3) using a small bulk lens. A beam focusing means is provided using one of the above. In general, beam directing means 1) use total internal reflection (TIR) of light from the slanted end face of the fiber with a slanted reflective surface, and 3) use a small bulk mirror. 4) Provided using one of four methods of using a reflective coating at the tip of the fiber. However, these methods have many inherent drawbacks, including excessive manufacturing costs, excessive size or insufficient freedom of choice of focal size and focal length.

There are many small optical systems known in the art that can be used to analyze the internal lumen structure. Each optical system can be conceptually divided into a beam focusing means and a beam directing means. Light travels from an external light source through one or more light illumination fibers (which can be essentially single-mode or multi-mode) to the internal lumen. The illumination fiber communicates the beam with a small optical system that focuses and directs the beam to the luminal wall. Light returns from the lumen to the extracorporeal analyzer using the same fiber or another fiber that is with the illumination fiber. In the design of some types of small optical systems, the focusing and directing means are carried out by separate optical elements. In another type of design, the focusing and directing means are carried out by the same element.

Some of the features of existing optics are undesirable. For example, in some devices, all diameters of the optics must be similar to the diameter of the optical fiber (often around 125 μm). This significantly narrows the options available for selecting focusing elements, beam magnifiers and beam directors, thus limiting the range of focal sizes and working distances that can be achieved by design. In addition, these very small devices are fragile, difficult to handle and fragile during manufacturing and operation. Third, in many embodiments, a gap must be provided to use the TIR to reorient the beam. This requires maintaining airtightness between the fiber and other elements in order to maintain air gaps. This becomes a problem when the device is immersed in water, blood or stomach acid or when the device is rotated or moved at high speed to form an image. Fourth, the GRIN focusing element has a rotationally symmetric index of refraction profile, which makes it impossible to correct the cylindrical aberrations introduced to the beam. The overall effect of these drawbacks is that certain small optics are expensive, difficult to manufacture, fragile, and do not produce a circular output at the focal plane.

In another approach, a lens system is formed by a molding method using a fusion spliced fiber portion together with a thin layer of polymer and epoxy. However, there are usually problems in the manufacture of molded lenses that include annular end faces and bore holes. Generally, during injection molding, the bore holes are formed by thin (135 μm / 220 μm) core pins located in the mold and supported on only one side of the molding tool. Problems arise due in part to the fact that this core pin can be distorted. Such strain can occur when a pressurized liquid polymer is injected into a mold and a force is applied to the core pins. If the force applied to the core pin is sufficiently greater than the rigidity of the core pin, the core pin will be distorted, resulting in molding defects such as non-uniform bores or diagonal bending.

In view of the various issues identified above and other issues, there is a need for optical lenses, assemblies and related manufacturing methods that do not require core pins during manufacturing. The present invention addresses this need and other needs.

In one aspect, the invention relates to a molded lens used with an optical fiber for OCT imaging. In one embodiment, the molded lens comprises a cylinder having a first end and a second end and defining a major axis. In another embodiment, the surface of the first end of the cylinder is inclined with respect to the major axis of the cylinder, and the second end defines a groove. In other embodiments, the grooves are sized to accept the optical fiber.

In one embodiment, the first end is a plane inclined to reflect light received from the optical fiber by reflection through the side of the cylinder. In another embodiment, the first end reflects light received from the optical fiber by reflection through a side portion of the cylinder and is tilted to focus the light at a position outside the cylinder. Define a plane. In yet another embodiment, the bore stops in a plane inclined with respect to the long axis of the cylinder. In yet another embodiment, the center of the bore major axis and the groove major axis is concentric with the cylindrical major axis. In other embodiments, the lens is made of a material selected from the group consisting of acrylics, polycarbonates, polystyrenes, polyetherimides, polymethylpentene and glass. In another embodiment, the lens is formed with a resin that can be poured into the lens to reduce the injection pressure and the corresponding stress on the tool during molding. After that, it is cured by a chemical reaction.

In another aspect, the invention relates to an OCT probe. In one embodiment, the OCT probe has a first end adapted to communicate with a light source, a second end, and an optical fiber that defines a major axis; the first end and A molded lens comprising a cylinder having a second end and defining a major axis, wherein the surface of the first end of the cylinder is tilted with respect to the major axis of the cylinder and the second end. The portion defines a groove or a bore, the groove and the bore include a molded lens configured to be sized to accept the optical fiber. In other embodiments, the optical fiber is held in the bore or groove by an adhesive. In yet another embodiment, the first end of the cylinder is a plane that is inclined to reflect the light received from the optical fiber by reflection through the sides of the cylinder. In yet another embodiment, the first end of the cylinder reflects light received from the optical fiber by reflection through a side portion of the cylinder to focus the light at a position outside the cylinder. Defines an inclined non-plane.

In yet another embodiment, the surface of the second end of the optical fiber is inclined with respect to the long axis of the optical fiber. In yet another embodiment, the angle of the second end of the optical fiber with respect to the major axis of the optical fiber is substantially the same as the angle of the plane tilted with respect to the major axis of the cylinder. In one embodiment, the optical fiber is held in the groove or bore with an adhesive having a refractive index that matches the material of the molded lens.

In yet another aspect, the invention relates to a molded lens used with an optical fiber for OCT imaging. In one embodiment, the molded lens has a first end and a second end, comprising a cylindrical solid defining a major axis, the surface of the first end of the cylindrical solid. Inclined with respect to the long axis of the cylindrical solid, the second end covers the first end of the metal tube, the optical fiber is bonded into the bore of the metal tube, and the first end of the metal tube. It extends from the end. In another embodiment, the first end of the cylindrical solid is an inclined plane to reflect the light received from the optical fiber by internal reflection through the side of the cylindrical solid. In yet another embodiment, the first end of the cylindrical solid reflects the light received from the optical fiber by internal reflection through the side of the cylindrical solid, and the light is reflected outside the cylindrical solid. Defines an inclined non-plane to focus in position.

In yet another aspect, the invention relates to an OCT probe. In one embodiment, the OCT probe has a first end adapted to communicate with a light source, a second end, and an optical fiber that defines a major axis; a first end. And a molded lens containing a cylindrical solid having a second end and defining a major axis, the surface of the first end of the cylindrical solid being on the major axis of the cylindrical solid. Inclined relative to, the second end covers the first end of the metal tube, the optical fiber is bonded into the bore of the metal tube and extends from the first end of the metal tube. , Including molded lenses. In another embodiment, the first end of the cylindrical solid is an inclined plane to reflect the light received from the optical fiber by internal reflection through the side of the cylindrical solid. In yet another embodiment, the first end of the cylindrical solid reflects the light received from the optical fiber by internal reflection through the side of the cylindrical solid, and the light is reflected outside the cylindrical solid. Defines an inclined non-plane to focus in position.

In yet another aspect, the invention relates to a lens. The lens includes a substantially cylindrical body having a long axis and including a fiber receiving end face defining a slot, a cylindrical outer surface, and a beam directional surface, the slot and liquid communicating, and a fiber receiving end face and beam directional. Arranged between surfaces, it has a first end and a second end, the groove defining the major axis is defined by a substantially cylindrical body and a cylindrical outer surface, and the beam directional surface is on the major axis. On the other hand, the groove is sized to accept an optical fiber. In one embodiment, the present invention relates to an intravascular imaging probe comprising an optical fiber arranged in a groove of a lens. The optical fiber can be placed in the torque wire. In one embodiment, the light exits from the end face of the optical fiber in the groove so that the divergent light is received by the lens. In one embodiment, the lens has a single structure.

The structure and function of the present invention can be best understood by reading the description of the present specification together with the accompanying drawings. The drawings are not necessarily on scale and the principles described are generally emphasized. The drawings are illustrative in all respects and are not intended to limit the invention. The scope of the present invention is defined only by the claims.
FIG. 1 is a block diagram of an image data collection system including a lens according to an embodiment of an exemplary lens of the present invention. FIG. 2A is a perspective view of an embodiment of an exemplary lens of the present invention. FIG. 2B is a cross-sectional view of the lens of FIG. 2A in the longitudinal direction. FIG. 2C is a top view of the lens of FIG. 2A. FIG. 2D is a side view of the lens of FIG. 2A. 2 (e) is a rear view of the lens of FIG. 2 (a). FIG. 2 (f) is a front view of the lens of FIG. 2 (a). FIG. 2 (g) is another perspective view of the lens of FIG. 2 (a). FIG. 3 is a photomicrograph of a molded lens according to an exemplary embodiment of the present invention. FIG. 4A is an OCT image of the lumen of a blood vessel taken with a lens. FIG. 4B is an OCT image of the lumen of a blood vessel taken with a molded lens according to an exemplary embodiment of the present invention. FIG. 5 is a schematic view of a mold for making a molded lens according to another embodiment of the present invention. FIG. 6 is a longitudinal side sectional view of a molded lens made according to the embodiment of the present invention shown in FIG. FIG. 7 is a longitudinal side sectional view of a lens assembly configured to be molded with a marker according to another embodiment of the present invention. FIG. 8 is a longitudinal top view of the probe constructed of the assembly of FIG. FIG. 9 is a side view of the probe of FIG. FIG. 10 is a side view of a lens including a marker according to another embodiment of the present invention.

Development of advanced optical analysis or imaging methods such as confocal microscopy, single-photon and multiphoton fluorescence imaging, harmonic imaging, optical spectroscopy and optical coherence tomography (OCT), industrial inspection, basic biology research It had a great impact on in vivo imaging of animals and humans. Although these methods differ in many ways, they share a common design property of focusing or collimating the incident light used to illuminate the target sample. Focused light has better localization of incident light for better spatial resolution and higher optical power density to produce higher signal levels than unfocused light. It brings a number of benefits, including that.

A focused or collimated beam is produced by directing the output of a light source through a series of optical elements that together form an optical system. The elements of the optical system are selected to obtain the desired focal size that occurs at a desired distance away from the last element of the optical system, called the "working distance." Each particular optical analysis application has its own optimum focal size and working distance. For example, confocal microscopy requires a small focal size close to 1 μm. On the other hand, OCT requires a medium focal size of about 5 μm to about 100 μm.

Optical systems consisting of conventional bulk lenses can be used to obtain a wide range of focal sizes and working distances, but in many applications flexible and compact optics for analyzing samples inside larger objects. A system is needed. Bioclinical medicine is an example of an area where this requirement is often required. Light from an external light source can be used in the optical analysis of luminal structures such as the esophagus, intestine, urinary tract, respiratory tract, lungs and blood vessels. The light is transmitted by the flexible probe, focused by a small optical system, and returned to the extracorporeal data analysis system through the flexible probe.

Furthermore, it is often desirable to analyze the luminal wall rather than the contents of the luminal, eg, to image the intima and medium of the vascular wall using OCT rather than imaging the blood contained in the blood vessel. This provides the additional design goal of directing the beam away from the long axis of the optical system or along other preferred directions (or ranges of directions). These types of optical probes are often referred to as "side-firing," "side-directed," "side imaging," or "side-looking." The size of these lumens is as small as several millimeters in the case of blood vessels, which makes the design of a small optical system considerably difficult. In addition, the embodiments described herein are also suitable for use in various embodiments of multifiber or fiber bundles. The various embodiments described below address these needs and other needs associated with probe components and beam formation.

Illustrative Embodiments of Focusing of Optical Fiber Beams The present invention relates in part to lenses or optics having an elongated three-dimensional shape, such as a substantially cylindrical solid. The lens defines the groove. The lens and the groove defined by the lens are configured to be large enough to accept the optical fiber portion, and operatively direct and focus the light. The lens can be fixed to an optical fiber and is used for both focusing and redirection of light outside the optics and for receiving light from the sample of interest. The present invention relates in part to a system and method of use that includes a predetermined lens embodiment and an optical fiber as part of an insertable probe. The probe can be used to perform an optical analysis of the luminal structure in vivo.

Another embodiment of the invention is such an apparatus for delivering focused or substantially collimated light to a sample and returning a portion of the light from the sample for processing in an imaging or data acquisition system. Also related to the design, manufacture and use of. A non-limiting example of an imaging system or a data acquisition system is an optical coherence tomography (OCT) system. FIG. 1 shows an exemplary OCT system including an exemplary light beam focusing element or lens according to an embodiment of the present invention.

Lens-based assemblies and other beam-directed optics can be used in a variety of examination and diagnostic applications. As shown in FIG. 1, one use of such lenses and beam directional optics is OCT. The OCT imaging catheter includes a beam director such as a tilt reflector or other beam directing element suitable for directing light to the inner wall of the coronary artery. Generally, an OCT imaging system includes a light source 10 that sends light to an interferometer 12 through an optical coupler 14 that is detachably connected to an optical fiber 16. There is a lens 25 at the end of the fiber 16 that sends light from the optical fiber 16 to the blood vessel 22 under study. The combination of the optical fiber 16 and the lens 25 is called an optical probe 20.

The optical probe 20 rotates, thereby illuminating a scan of the wall of blood vessel 22 with a single rotation. The light reflected by the wall of the blood vessel 22 is collected by the lens 25 and reaches the interferometer 12 through the optical fiber 16. The resulting interference pattern is detected and analyzed, and the resulting image is displayed on the display 24. As shown, the lens includes a groove 28 sized to accommodate the optical fiber 16. An adhesive is usually placed in or on the groove 28 to secure the optical fiber 16 to the lens 25.

The present invention relates in part to, for example, the elongated lens 25 shown in FIGS. 2 (a) to 2 (f). The lens 25 is configured to define a substantially cylindrical outer surface 52 having a groove 58 that receives the optical fiber. The use of core pins used in the manufacture of prior art lenses and related manufacturing requirements because the elongated optics include a groove 58 capable of receiving the optical fiber (eg, by dropping the optical fiber into the groove 58). The problem is avoided.

In one embodiment, the optical fiber received in the groove 58 of the embodiment of a given lens includes an optical fiber end face. The optical fiber arranged in the groove is configured to transmit and receive optical signals. The light beam exiting the fiber optic end face spreads or diverges from the end face. Thus, the lens provides beam orientation or focusing instead of using a GRIN lens with an optical fiber. Unlike prior art lens bores (all sides are surrounded by a material that constitutes or defines the bore), the groove 58 that receives the optical fiber has a slit or U-shaped appearance. That is, the groove 58 is partially surrounded by the two walls of the groove and the bottom of the groove to form a slit or groove region for receiving the optical fiber and adhering the optical fiber to the lens.

In one embodiment, the bottom and walls of the groove may be curved, straight, or a combination thereof. In one embodiment, the groove defined by the lens has a width in the range of about 80 μm to about 300 μm so that the groove can accept the optical fiber. In one embodiment, the groove defined by the lens has a length in the range of about 0.2 mm to about 3 mm to ensure that the optical fiber is adhered to the groove. In one embodiment, the groove defined by the lens has a height chosen so that the center of the optical fiber is located along the long axis of the lens. Therefore, the groove is configured to have a height that is longer / deeper than the width of the groove, for example, as indicated by the boundary portion of the groove. Similarly, in one embodiment, the width of the groove is configured to be smaller than the length of the groove, as indicated by, for example, the distance between the optical fiber receiving end face and the groove boundary. In one embodiment, the lens is made of a single material, for example by injection molding.

More specifically, with reference generally to FIGS. 2 (a) to 2 (f), the lens 25 includes a beam transmission surface 50. The beam transmission surface 50 is also referred to as a front end surface, a beam directional surface, or a beam focusing surface. In FIGS. 2 (c) and 2 (d), λ indicates a region where light exits the surface 50 as a result of light moving through the optical fiber in the groove 58 along the major axis L of the lens 25. In one embodiment, the beam transmission surface 50 is a generally flat surface or a substantially flat surface that is inclined with respect to the long axis L of the lens, and is a cylindrical body 52 of the lens 25. Reflects and directs light from an optical fiber that exits through a side. In another embodiment, the front end face 50 is curved to define the lens and focus the light directed by the sides of the cylinder 52 at a particular working distance. In one embodiment, the beam directional plane 50 is one of, but not limited to, a biconic asphere, an asphere, a biconic Zernike, Fresnel and a non-uniform rational B-spline. It can be formed to include one or more.

In one embodiment, the diameter of the lens 25 is increased at one or more transition cross sections between the beam directional surface 50 and the groove 58. The step in diameter allows the lens to be inserted into another component of the imaging catheter (eg, an opaque marker band) with a defined portion of the lens extending outside the other component.

In one embodiment, the center of the groove 58 is concentric with the major axis L of the cylindrical body 52. In one embodiment, the cylindrical body 52 is a substantially cylindrical solid having an end face 64 at one end and a beam transmission surface 50 at the other end, as shown in FIG. 2 (f). In particular, with reference to FIG. 2 (c), the inner end face 64 of the lens adjacent to the end face of the optical fiber (when the optical fiber is installed in the groove) is also inclined, and the light is reflected to the optical fiber. It is polished with high precision to suppress the artifacts of the OCT image caused by returning. In one embodiment, the range of angles shown between the major axis L in FIG. 2B and the straight line along the surface 50 is from about 5 ° to about 25 °. In one embodiment, the optical fiber selected for inclusion in the groove 58 is also angle-cleaved or angle-polished to reduce back reflection.

In one embodiment, the optical fiber is fixed in the groove 58 using an adhesive. By using an open flow path or groove 58 instead of the bore hole, with reference to FIGS. 2 (b), 2 (d), 2 (e), 2 (f) and 2 (g). As shown in FIG. 1, the formation of bubbles when the optical fiber is fixed in the groove 58 is reduced. This is because the bubbles are naturally discharged upward through the open region of the groove 58 formed in the cylindrical body 25. When the optical fiber is adhered to the molded lens, an adhesive having a refractive index close to that of both the polymer used for manufacturing the molded lens and the optical fiber can be used. In order to suppress the back reflection at the optical interface of materials with different refractive indexes, the refractive index mismatch of the adhesive should be avoided or suppressed as much as possible.

In addition, because the optical fiber is inserted into the groove, the lens design allows the catheter to be constructed with a single continuous optical fiber with a continuous layer of intact polyimide protective coating. The use of fiber optics without stripped regions or fusion splicing maximizes the overall strength of the assembly and minimizes the possibility of breakage.

More specifically, the groove is configured to have a protective coating such as polyimide and to be large enough to accept a single-mode optical fiber having an overall diameter of about 105 μm to about 155 μm. .. Since the groove 58 extends along the surface of the lens, the groove 58 can be formed by a solid fin of tool metal rather than the core pins used in the prior art to form the bore. In one embodiment, the hard fin is integral with the rest of the tool metal that forms the upper half of the molded lens. The groove-forming fins are even stronger than the core pins and are supported over their entire length so they do not distort. This solves the problem of core pin distortion described earlier.

A micrograph of the molded lens taken perpendicular to the groove is shown in FIG. As shown, the groove 58 is formed in the cylindrical body 52. The lens has a transition region 70 between the first portions of the lens having the first cross-sectional diameter. At the transition region 70, the first cross-sectional diameter steps up to a second cross-sectional diameter that includes a subset of the grooves 58. This transition region or cross section 70 is also shown in FIG. 2 (b). In one embodiment, the range of the first cross-sectional diameter of the lens is from about 150 μm to about 800 μm. In one embodiment, the range of the second cross-sectional diameter of the lens is from about 300 μm to about 1000 μm.

In addition, in one embodiment, the end face 64 of the lens shown in FIG. 3C is adjacent to the groove 58 in order to suppress backward reflection of light. In one embodiment, the inner end surface 64 is tilted with respect to the long axis of the lens and is polished to suppress back reflection. This point is important. Is because the OCT system is lower where is because sensitive to back reflection and -100 dB (part of ¹⁰ -10) ~-120 dB (part of ^{10 -12).} To obtain this level of back reflection, the end face 64 is tilted from about 5 ° to about 25 °, polished with high precision and has a surface roughness of less than 30 nm. The combination of tilting and polishing of the end face 64 can suppress the backward reflection of light to an acceptable level. In addition, the end face of the optical fiber itself is also cleaved or diagonally polished at 5 ° to 25 ° to prevent back reflection from the end face of the optical fiber.

The manufacturing process can be further simplified by directly cleaving the optical fiber through a polyimide protective film instead of mechanically polishing the optical fiber. Direct cleavage has the additional advantage that the entire catheter can be constructed with a single continuous optical fiber with a continuous layer of polyimide protective coating (ie, without areas to be removed or fusion splicing). Maintaining fiber-coating consistency throughout the catheter maximizes strength and reduces the potential for breakage.

The imaging performance of the lenses described herein was evaluated in animal experiments. The image quality was compared with that of a conventional lens design using a graded index fiber optic section for beam focusing and a total internal reflection air glass interface for beam orientation. Sample images are shown in FIGS. 4 (a) and 4 (b). The microscopic image (FIG. 4 (a)) shows an OCT image of a blood vessel taken using a conventional lens design. FIG. 4B shows an OCT image of a blood vessel taken with an elongated molded lens cap having an annular end face and a groove and avoiding the use of core pins during manufacturing. As is clear from the image on the right (FIG. 4 (b)), the resulting image is bright and the surface of the dark areas and the like shown in the top quarter of FIG. 4 (b). The resolution for the details below is increasing.

With reference to FIG. 5, in another embodiment, the molded lens is formed by first inserting the optical fiber 80 into the metal tube 84. One end 82 of the optical fiber 80 is arranged so as to extend beyond one end of the metal tube 84. The combination of the optical fiber and the metal tube is glued together with adhesive 85 and placed in a mold assembly 86, 86', 86'(usually 86). The mold assemblies 86, 86 ″, 86 ″ include a shoulder portion 87 to prevent the combination of the metal tube 84 and the bonded optical fiber 80 from leaving the mold 86. Since the optical fiber 80 is adhered to the metal tube 84, pushing back is prevented. Alternatively, press the fiber into half of the mold to keep it in place. This eliminates the need for glue.

In addition, the front 89 of the mold assembly is polished to form an optical surface on the lens. In this method, the optical fiber 80 is not directly held by the mold 86, which reduces the possibility of damaging the optical fiber 80. Further, since the combination of the metal tube 84 and the optical fiber 80 is rigid, the position where the plastic is put into the mold 86 can be made close to the polishing surface 89, and the flow of the plastic can be directed toward the metal tube 84. .. Even if the metal tube 84 is damaged, it is unlikely that the metal tube 84 will move toward the polished surface 89 in the mold 86 and damage it.

With reference to FIG. 6, the mold 86 is then filled with plastic or other lens material described above. Once the lens plastic has solidified, the assembly of the optical fiber 80 and the metal tube 84 is removed from the mold 86. Then, the optical fiber 80, the metal tube 84, and the lens 25 form an OCT probe.

In one embodiment, the outer diameter of the optical fiber is about 0.006 inches, the inner diameter of the metal tube is about 0.0065 inches, and the outer diameter of the metal tube is about 0.0095 inches. The outer diameter of the injection molded plastic lens is about 0.014 inches. The wall thickness of about 0.002 inches of plastic around the metal tube is within the manufacturing capacity of micromolding. The wall thickness of about 0.0015 inches of metal tubing is sufficient to provide rigidity over the short length of tubing in the mold.

The metal tube 84 is a structural support column that prevents the optical fiber 80 from being damaged at a position where the optical fiber 80 exits the mold lens 25. The tendency of the optical fiber 80 to break at the above position is partly due to the large diameter difference between the optical fiber and the molded lens that causes a large change in rigidity. Further, the molded lens 25 causes hoop stress in the optical fiber 80 due to the shrinkage of the plastic during molding. Normally, this hoop stress applies additional stress to the optical fiber 80 where the optical fiber 80 exits the mold 86. The metal tube 84 protects the optical fiber 80 from hoop stress at the proximal fiber exit from the molds 86, 86'.

In addition to protecting the area of the optical fiber 80 where the optical fiber 80 exits the mold 86, the metal tube 84 also protects this area of the optical fiber during use. That is, the optical fiber sucks up the tensile load of the rotating optical fiber image core during the pullback of the optical fiber image core. Without the metal tube that attaches the optical fiber 80 to the mold lens 25, the region of the optical fiber 80 for this force transmission would be only the length of the optical fiber 80 inserted into the mold lens.

The adhesive joint 84 between the optical fiber 80 and the metal tube 84 provides a large surface area for the transmission of tensile load forces. In addition, the metal tube 84 provides a stiffness transition from the molded lens 25 to the optical fiber 80, further reducing the stress on the optical fiber 80. The use of smaller optical fibers, such as 80 μm coated OD, is also practical in this design. The stress exerted by the small optical fiber when the assembly is bent in the artery is small, which is useful because it reduces the possibility of breakage.

More importantly, in this molding method, the end face 82 of the optical fiber can be covered with plastic, so that a good optical joint can be formed in the optical path without an adhesive. Since the end 82 of the optical fiber 80 extends beyond the metal tube, it is unlikely that air will be trapped at the end of the optical fiber. If air is trapped, it interferes with the optical junction between the end face of the optical fiber and the molded lens. The end of the optical fiber may be cleaved diagonally to suppress back reflection.

As shown in FIG. 7, in another embodiment, the lens 25 is formed into the opaque marker 100 together with the optical fiber 80. As shown in FIG. 7, the unstripped optical fiber 80 is cleaved obliquely and inserted into the short portion of the tube 84, with the tube 84 inserted into the marker 100. The assembly is pressed against a jig (not shown) on the right side of FIG. 8 to align these components. Adhesive 104 attaches the components as shown. As explained earlier, this assembly is inserted into the mold. The mold fixes the end of the marker 100 to position it. Then, the mold is filled with plastic to form a lens.

After that, the lens 25 is subjected to a reflective coating, and the torque wire 108 or another twisting device is slid into the marker 100 and adhered to the marker 100. This completes the assembly shown in FIG.

The fiber 80 does not have to extend far outward from the tube 84. This is because the main connection between the optical fiber 80 and the lens is the marker 100. Only the surface of the optical fiber needs to be molded into the lens. By selecting a plastic having a low melting temperature, the tube 84 is melt-bonded to the plastic. This helps with the strength of the assembly.

In yet another embodiment, the short portion of the tube 84 may be removed as shown in FIG. In this embodiment, instead of the torque wire 108, a very thick coating 120 on the fiber optic glass 80 may be used as the twisting device. In this case, the core and coating of the optical fiber are simply inserted into the marker 100 and the lens 25 and molded into the marker 100. As such, the assembly is optically aligned during the molding process. This is a repeatable alignment method. The joint between the marker and the lens is very strong, which makes the assembly strong. Since the surface of the optical fiber is inserted and molded into the lens, the optical path is not affected by air bubbles in the adhesive. Therefore, by removing the tube 84, it becomes possible to design a small size as a whole.

The embodiments, embodiments, features and examples of the present invention are for illustration purposes in all respects and are not intended to limit the present invention. The scope of the present invention is defined only in the claims. Other embodiments, modifications and uses will be apparent to those skilled in the art without departing from the spirit and scope of the invention.

The use of headings and sections in the present application does not imply limiting the invention, and each section may fall under any of the embodiments, embodiments or features of the invention.

Throughout the application, if the composition is described as having, containing or containing a particular component, or if the method is described as having, containing or containing a particular method step. The compositions of the teachings of the present application are substantially composed of or consist of enumerated components, and the methods of the teachings of the present application are substantially composed of or enumerated in the enumerated method steps. It is also conceivable that it consists of the method steps described.

If it is stated in the present application that an element or component is included in a list of listed elements or components and / or is selected from a list of listed elements or components, such element or component is listed. It can be seen that it is any one of the specified elements or components, and can be selected from the group consisting of two or more of the listed elements or components. Also, the elements and / or features of the compositions, devices or methods described herein may be combined in various ways, express or implied, without departing from the spirit and scope of the teachings of the present application. it can.

The use of the terms "include" and "have" should be understood to be open-ended and non-limiting unless otherwise noted.

The use of the singular herein includes plural unless otherwise noted (and vice versa). Furthermore, the singular forms "a", "an" and "the" also include the plural form unless otherwise noted. In addition, when the term "about" is used before a quantitative value, the teachings of the present application also include the particular quantitative value itself, unless otherwise noted.

The order of steps or the order for performing a specific operation is not important as long as the teachings of the present application can be operated. Further, two or more steps or operations may be performed at the same time.

Where a range or list of values is provided, each value intervening between the upper and lower limits of such range or list of values is individually as each value is specifically described herein. Examined and included in the present invention. In addition, a small range between the upper and lower limits of a predetermined range and including the upper and lower limits is conceivable and is included within the present invention. The list of exemplary values or ranges does not abandon other values or ranges between the upper and lower limits of a given range and including upper and lower limits.

The drawings and description of the present invention have been simplified to explain the elements related to a clear understanding of the present invention, while other elements have been excluded for clarity. However, those skilled in the art may recognize that those and other factors are desirable. However, the description of such elements is omitted herein because such elements are known in the art and they do not promote a better understanding of the present invention. The drawings are presented for the purpose of illustration, not as assembly drawings. The omitted details and modified or alternative embodiments are within the scope of those skilled in the art.

The present invention can also be practiced in other particular embodiments without departing from its spirit or basic characteristics. Therefore, the aforementioned embodiments are considered in all respects to be exemplary rather than limiting the inventions described herein. Therefore, the scope of the present invention is shown in the attached claims rather than the above description, and all changes within the meaning and equality of the claims are included in the scope of the present invention.

Claims (17)

A substantially cylindrical body having a major axis and including a first end, a cylindrical outer surface, and a beam directional surface at the second end, the substantially cylindrical body containing a polymer. body,
Is a lens that includes
The substantially cylindrical body and the cylindrical outer surface define a groove open in a direction perpendicular to the longitudinal axis of the substantially cylindrical body between the first end portion and the beam directional surface, and the open groove is defined as a groove. Define the inner end face,
The beam directional surface is inclined with respect to the major axis and
The open groove is sized to accept an optical fiber, the inner end surface is polished, and the optical fiber is oblique to the longitudinal axis when viewed from above the open groove. Is placed in the open groove, the end face of the optical fiber is placed adjacent to the inner end face .
lens. The lens according to claim 1, wherein the lens is formed by molding the polymer. The lens according to claim 1, further comprising an optical fiber and an adhesive, wherein the optical fiber is arranged in the open groove and fixed by the adhesive. The lens according to claim 1, wherein the beam directional surface defines a non-plane surface arranged so as to direct the light so that the light received from the optical fiber is focused on the outside of the lens. The open groove defines a major axis, the major axis of the substantially cylindrical body is concentric with the major axis of the open groove, and the inner end surface is opened to suppress back reflection to the optical fiber. The lens according to claim 1, which is inclined obliquely with respect to the long axis of the groove. The lens according to claim 3, wherein the light from the optical fiber is diverged and focused by the lens. The end of the optical fiber is oriented at a first angle, the beam directional surface is directed at a second angle with respect to the beam directional surface, and the second angle is different from the first angle. , The lens according to claim 1. The lens according to claim 1, wherein the shape of the lens is selected from the group consisting of a biconic aspherical surface, an aspherical surface, a biconic Zernike, Fresnel, and a non-uniform rational B-spline. The lens of claim 7, further comprising a metal tube having a first end and a second end and defining a tubular bore, wherein the optical fiber is fixed to the tubular bore with an adhesive. The lens according to claim 2 , wherein the molded lens has a cross section having a diameter of about 150 μm to about 800 μm. The lens according to claim 10, wherein the molded lens has a transition region, and the diameter changes in the transition region. The lens according to claim 2 , wherein the optical fiber and the molded lens rotate together in response to rotation of the optical fiber. The lens according to claim 1, wherein the lens has a cross section having a diameter of about 150 μm to about 800 μm. 13. The lens of claim 13, wherein the lens has a transition region and the diameter varies in the transition region. The lens according to claim 1, wherein the beam directional surface of the lens is configured to reflect light received from the optical fiber through a side portion of the substantially cylindrical body. The lens according to claim 1, wherein the polymer is a material selected from the group consisting of acrylics, polycarbonates, polystyrenes, polyetherimides and polymethylpentene. The lens according to claim 1, further comprising an interferometer that optically communicates with the lens.

Images