referring now to the drawings , wherein like numerals indicate like elements , there is shown in fig1 a probe 10 in accordance with a first embodiment of the present invention . probe 10 comprises a tip portion 12 and a light guide 14 for conducting light energy from a light source ( not shown ) to tip portion 12 . preferably , light guide 14 is a fiber optic or other flexible light guide means . light guide 14 may be contained within a supporting means 16 , which may be in the form of a thin walled , hollow tube . supporting means 16 may conveniently be provided with a recessed counterbore 18 for receiving and retaining tip portion 12 . tip portion 12 may accordingly be provided with a cylindrical shank portion 20 which may be received in counterbore 18 . shank portion 20 has a generally planar face 22 which receives light energy form the output face 24 of light guide 14 . as shown in fig1 there is a small gap 26 between faces 22 and 24 , although a gap is not necessary as will be seen in connection with further embodiments of the invention to be described below . tip portion 12 consists essentially of light propagating material 28 . light propagating material 28 is an inorganic compound , and includes inorganic oxides , such as glasses ( e . g ., fused silica ( sio 2 )), and ceramics , such as aluminum oxide ( al 2 o 3 ). the ceramics may include dopants such as magnesium ( mg ) and chromium ( cr ). light propagating material 28 also includes other inorganic compounds such as zinc selenide ( znse ), zinc sulfide ( zns ) and the like . the light propagating material 28 is preferably aluminum oxide ( al 2 o 3 ), also known as sapphire . sapphire is preferred because it is physiologically neutral , has high mechanical strength , high hardness , high light transmission , excellent thermal resistance and high thermal conductivity , and exhibits low tissue adhesion when used in contact procedures . in certain procedures , temperatures above 1000 ° c . are encountered , and thus light propagating material 28 should be capable of withstanding such temperatures . for example , one such procedure is the use of a laser to vaporize tissue for surgery . in other procedures , temperatures as low as physiological temperature ( body temperature ) are encountered . examples of such procedures include photodynamic therapy and biostimulation . many additional procedures span the temperature range between these two extremes . an important feature of light propagating material 28 is that it contains inclusions 30 distributed throughout the material for interacting with light energy fed into tip portion 12 from light guide 14 . in fig1 only a few inclusions , sufficient to illustrate the invention , are shown . inclusions 30 may interact with light energy , represented in fig1 by rays 32 and 34 , to identify only two rays , by scattering the light energy or by absorbing the light energy , or both . that is , the inclusions 30 may be of a type that scatters light energy without significant absorption , or a type that absorbs light energy without significant scattering , or may comprise both types . types of inclusions that tend to scatter more than absorb light energy include reflective metal particles such as aluminum , gold or similar metals , or even transparent materials with refractive indexes different from the refractive index of the light propagating material 28 , such as diamond , zirconium oxide , and like materials . in addition , inclusions that tend to scatter rather than absorb light energy may be grain boundaries of a polycrystalline material such as zinc selenide ( znse ). types of inclusions that tend to absorb rather than scatter light energy include particles of carbon or graphite , iron oxide , manganese dioxide , and like materials . either one or both types of inclusions may be present in light propagating material 28 , as may be desired . thus , if a relatively low temperature , high scatter probe is desired , only inclusions that scatter rather than absorb light energy will be preferred . where it is desired to have a probe that operates at a very high temperature , only inclusions that absorb rather than scatter light energy will be preferred . a preferred material for light propagating material 28 is a form of aluminum oxide sold under the trade name &# 34 ; lucalox .&# 34 ; this material has a purity of 99 . 9 % aluminum oxide and is free of intentionally - introduced materials or dopants . this material has inclusions in the form of porosity and grain boundaries , which act to scatter light energy without appreciable absorption . another suitable material for light propagating material 28 is a quartz product sold commercially under the trade name &# 34 ; gelsil .&# 34 ; this material is a high purity ( greater than 99 %) porous silica ( sio 2 ) material with internal voids ranging in size from 25 to 200 angstroms , which scatter light energy without significant absorption . although this material , being quartz , is not as tough as aluminum oxide , and does not possess the high temperature characteristics of aluminum oxide , it may be suitable for many lower temperature , lower mechanical stress applications , or in applications in which the probe may have a sufficient size to provide the required mechanical strength . dopant materials can be intentionally introduced into light propagating material 28 to absorb light energy . such light energy absorbing dopant materials may be introduced instead of , or in addition to , light scattering inclusions . materials such as carbon or manganese dioxide ( mno 2 ), to name only two , may be used as light energy absorbing dopants . as shown in fig1 light energy will be scattered from all surfaces of tip portion 12 due to the presence of inclusions 30 , which scatter the light energy . thus , light energy entering planar face 22 of tip portion 12 will immediately encounter light scattering inclusions 30 , with the result that light energy will be emitted in a distribution pattern in all directions around the entire outer surface of tip portion 12 . the distribution pattern illustrated in the figures herein is for an optically clear light propagating medium , such as , for example , air , saline or water . the distribution pattern may be changed , however , by locating the output face of the light guide within the tip portion of the probe . for example , referring now to fig2 tip portion 36 as shown in fig2 is substantially identical to tip portion 12 shown in fig1 except that tip portion 36 has an axial bore 38 therein for receiving light guide 14 . thus , output face 24 of light guide 14 is located within and surrounded by light propagating material 28 of tip portion 36 . because output face 24 is located within light propagating material 28 , most of the light energy conveyed to tip portion 36 by light guide 14 can be emitted from the forward end of tip portion 36 , within the volume defined by the dashed envelope 40 in fig2 . thus , in the embodiment illustrated in fig2 the probe has a light energy output pattern in which most of the light energy is emitted from the forward end of tip portion 36 . the light energy output pattern of this embodiment peaks at the axis of tip portion 36 and decreases in radial directions away from the axis . the tip portion may have many shapes . thus , for example , as shown in fig3 a generally spherical tip portion 42 may be provided . as with tip portion 36 , tip portion 42 may be provided with a bore 38 for receiving light guide 14 therein . the shape shown in fig3 can give a light energy output pattern defined by envelope 44 . envelope 44 defines a generally spherical light energy output pattern in which light energy is generally forwardly directed from tip portion 42 . fig4 illustrates a shape of a probe tip portion 46 according to the invention in which the energy distribution is relatively constant over a circular area in a plane perpendicular to the axis of the tip portion , as shown by envelope 48 . in fig4 tip portion 46 is generally cylindrical in shape . as with tip portion 36 , tip portion 46 may be provided with a bore 38 for receiving light guide 14 therein . the light energy distribution pattern can be modified not only by altering the shape of the tip portion , but by altering the extent to which light guide 14 extends into the interior of the tip portion . for example , as shown in fig5 tip portion 48 is the same shape as tip portion 46 shown in fig4 . however , as seen by comparing fig4 and 5 , light guide 14 extends into tip portion 48 for a much shorter distance than light guide 14 extends into tip portion 46 . this results in a light distribution pattern which is generally more conical in shape , as shown by envelope 50 . the light energy distribution pattern thus not only depends on the shape of the tip portion , but on the extent to which light guide 14 extends into the tip portion . fig6 illustrates still another embodiment of the invention , in which the light propagating material 28 is located on only the surface of tip portion 52 . thus , tip portion 52 comprises an optically clear material 54 surrounded by light propagating material 28 . optically clear material 54 may be any suitable optically clear material , such as any of the materials already mentioned , including aluminum oxide , or the like . preferably , however , optically clear material 54 is air , in which event tip portion 52 is in the form of a generally hollow shell surrounding light guide 14 . alternatively , tip portion 52 can be a composite monolithic material with light propagating material 28 being a scattering portion and optically clear material 54 being an optically transmissive portion . in this embodiment , the light energy distribution pattern is illustrated by envelope 56 . still another shape of the tip portion according to the present invention is illustrated in fig7 and 8 . the shape illustrated in fig7 and 8 is an asymmetrical shape which comprises a generally cylindrical portion 58 having a spherical projection 60 on one side of the axis of generally cylindrical portion 58 . light guide 14 is located generally coaxial with the axis of cylindrical portion 58 . the shape illustrated in fig7 and 8 gives a light energy distribution pattern indicated by envelope 62 which is asymmetric with respect to the axis of light guide 14 . this shape permits surgical procedures either in front of or lateral to the axis of light guide 14 . it should be understood that , although several different shapes have been shown for purposes of illustrating the invention , other shapes may be employed without departing from the scope of the present invention . the light energy distribution pattern can also be changed as a function of light - scattering inclusions in the light propagating material . thus , a large number of such inclusions would yield a highly - diffuse distribution pattern , while a smaller number of such inclusions would yield a more concentrated distribution pattern . the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and , accordingly , reference should be made to the appended claims , rather than to the foregoing specification , as indicating the scope of the invention .