Patent Application
20110141759
This invention relates to optical surgical probes and, more particularly, to a multi-spot laser surgical probe using faceted optical elements.
Optical surgical probes deliver light to a surgical field for a variety of applications. In some applications, it may be useful to deliver light to multiple spots in the surgical field. For example, in pan-retinal photocoagulation of retinal tissue, it may be desirable to deliver laser light to multiple spots so as to reduce the time of the pan-retinal photocoagulation procedure. Various techniques have been employed to produce multiple beams for a multi-spot pattern. For example, one approach uses diffractive elements to divide an incoming beam into multiple spots. But it is also desirable to have a multi-spot generator that can be placed at a distal end of the optical surgical probe to more easily produce multiple spots from a single input beam, so that the multi-spot generator can more easily be used with existing laser sources without the need for additional components to align the laser surgical probe with the sources.
Difficulties can arise in the use of diffractive elements at a distal end of the optical surgical probe. As one example, diffractive elements produce a multitude of higher diffraction orders, and while these orders are relatively lower in light intensity as compared to the primary spot pattern, they may not always be negligible in terms of their effects. As another example, a diffractive element may not perform identically in different refractive media. For example, if the diffractive element is placed into a medium other than air, such as saline solution or oil, spaces between the diffractive elements can be filled with material having a different refractive index than air, which can ruin the spot pattern. As yet another example, the spacing between the spots can vary for different wavelengths, which can be problematic when an aiming beam is of a certain color while a treatment beam is of a different color. Lastly, diffractive elements are frequently expensive and difficult to produce, and this is particularly the case when the diffractive element must be constructed to fit into a small area, such as a distal tip of a surgical probe for surgical instruments that are 23-gauge or smaller. Thus, there remains a need for an optical surgical probe that can produce multiple spots at a target area using optical elements at a distal end of the surgical probe.
In particular embodiments of the present invention, an optical surgical probe includes a handpiece, a light guide within the handpiece, and a multi-spot generator at a distal end of the handpiece. The handpiece is configured to optically couple to a light source. The light guide is configured to carry a light beam from the light source to a distal end of the handpiece. The multi-spot generator includes a faceted optical element with a faceted end surface spaced from a distal end of the light guide. The faceted end surface includes at least one facet oblique to a path of the light beam. In various embodiments, the faceted end surface may be convex or concave. In certain embodiments of the present invention, the multi-spot generator further includes a focusing element, such as a gradient index (GRIN) lens or a sapphire ball lens. In certain embodiments, the faceted end surface is formed in optical adhesive, and the multi-spot generator may include multiple optical adhesive materials.
In particular embodiments of the present invention, a method of manufacturing a multi-spot optical surgical probe includes depositing an optical adhesive in a cannula for a handpiece. The handpiece for which the cannula is formed includes at least one light guide configured to carry a light beam from a light source through the handpiece. The method further includes forming the optical adhesive to produce a faceted face. The method also includes curing the optical adhesive. The method additionally includes assembling the cannula with the handpiece to form a multi-spot generator that includes the optical adhesive at a distal end of the handpiece. In various embodiments, the optical adhesive may be formed on or around a focusing element, such as a GRIN lens or a sapphire ball lens. In certain embodiments, multiple optical adhesive materials may also be used.
Other objects, features and advantages of the present invention will become apparent with reference to the drawings, and the following description of the drawings and claims.
A light guide 108 delivers a light beam to a proximal planar face of the proximal faceted optical element 104. Although the light guide 108 could in principle be any suitable structure for transmitting light to the distal end of the handpiece 100, optical fibers are most commonly used in surgical applications. The central axis of the emitted beam from the light guide 108 is referred to as the “beam path.” The light beam diverges as it travels away from the light guide 108 to a degree that depends on the numerical aperture for the light beam coupled into the light guide 108. For this reason, the faceted optical surface of faceted optical elements is spaced from a distal end of the light guide 108 so that portions of the diverging beam are refracted to different locations. In various embodiments of the invention, at least one facet is oriented such that a direction normal to a facet at a center of the facet is not parallel to the beam path of the emitted light beam. Such facets are described herein as being “oblique to the beam path.”
The faceted optical elements 104 and 106 each have different refractive indices, so that as the beam exiting the light guide 108 diverges, the faceted interface between the concave faceted face of the proximal optical element 104 and the convex faceted face of the distal optical element 106 produces multiple spots emerging from a distal planar face of the distal faceted optical element 106. “Concave” and “convex” in this context refer to whether the faceted surface is formed inwardly or outwardly of the optical element along the beam path. Depending on the relative refractive indices of the distal faceted optical element 106 and the medium into which the surgical probe is inserted, the spots could further diverge as they pass from the distal face of the optical element 106 into the medium. In a particular example in which the surgical probe is being designed for use in saline solution, for example, the proximal faceted optical element 104 could have an index of refraction of 1.36 and the distal faceted optical element could have an index of refraction of 1.58, which can produce a spot spacing on the order of a millimeter for a target around 4 mm away, assuming an angle between the facets and the beam path is in the range of 35 to 55 degrees.
In the depicted embodiment, the optical elements 104 and 106 each have four triangular facets oblique to the beam path that meet at a point aligned with a center of the light beam from the light guide, so that the multi-spot generator 102 produces four output spots. In principle, however, the number and shape of the facets could be adjusted to produce a desired pattern of output spots. For example, the number of facets could be increased. In another example, there could be a central planar facet perpendicular to the beam path with surrounding obliquely-angled facets to produce a central spot surrounded by multiple spots.
The faceted optical elements 104 and 106 may advantageously be formed of optical adhesives. Using optical adhesives to form faceted optical elements has several technical advantages. One advantage is that the refractive index of the faceted optical elements 104 and 106 can be selected from a number of available materials. Another advantage is relative ease of forming the faceted surface as compared to harder refractive materials that may be difficult to mold, etch, cut, or machine into a suitable shape. A third advantage is that the optical adhesive material can be relatively durable in use as compared to other optical elements, like diffraction gratings, that can be relatively fragile. A fourth advantage is that the optical adhesive may be formed around other optical components, allowing the optical adhesive and the other optical components to work together in generating a multi-spot pattern.
As one example of how a faceted optical element can be formed around another optical component,
An alternative embodiment incorporates a proximal focusing lens and a faceted surface of the faceted optical element.
At step 408, a second optical adhesive is deposited on the distal face of the previously-cured optical adhesive. The second optical adhesive conforms to the concave faceted surface of the first optical adhesive to produce a convex faceted surface in the second optical adhesive. The distal surface of the second optical adhesive may then be flattened by pressing down a mold plate. Alternatively, the deposition of the optical adhesive can be otherwise controlled to produce a desired shape, such as by introduction into a closed mold volume. In the latter case, two faceted surfaces could be formed if desired. At step 410, the second optical adhesive is cured to harden it in the desired shape. Different curing processes may be used for the first and second optical adhesives. For example, if the adhesive is light-cured, a wavelength of light used to cure the second adhesive may be different than a wavelength used to cure the second adhesive, so that there are no negative effects from overexposure of the first adhesive to curing radiation. In another variation for light-cured adhesives, a mold plate or other closed mold used to form the second optical adhesive may also be made from a material transparent to curing radiation (e.g., quartz for UV curing radiation), so that the second adhesive may be cured with the mold plate still in place. The mold plate can then be removed after curing. The cannula with the first and second optical adhesives may then be assembled into a surgical handpiece at step 412 to complete the method.
At step 506, a faceted surface is formed on a proximal end of the optical adhesive. The faceted surface may be convex or concave. The faceted surface may be formed, for example, by using a pin with a complementary faceted surface on the end that is inserted into a proximal end of the cannula. At step 508, the optical adhesive is cured, hardening the optical adhesive in the desired shape and allowing the molding pin and the mold plate to be removed. The handpiece is assembled with the cannula at step 510, completing the method.
The present invention is illustrated herein by example, and various modifications may be made by a person of ordinary skill in the art. Although the present invention is described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the scope of the invention as claimed.
This application claims priority to U.S. provisional application Ser. No. 61/285,400 , filed on Dec. 10, 2009, the contents which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61285400 | Dec 2009 | US |
