Device for therapeutic electromagnetic treatment

Device for the treatment of vascular injuries

Field of the Invention

The present invention relates generally to the field of therapeutic electromagnet treatment, and more particularly to a method and apparatus for using a spatially expanded pulsed light source such as a flash lamp (s) for such treatment, or effectively concentrating light from a flash lamp to optical fibers for other therapeutic applications.

Background of the Invention

It is known in the art to use electromagnetic radiation in medical applications for therapeutic purposes such as the treatment of skin disorders. For example, U.S. Patent No. 4,298,005 to Mutzhas describes a permanent ultraviolet lamp for cosmetic, photobiological and photochemical applications. A treatment based on the use of the UV portion of the spectrum and its photochemical interaction with the skin is described. The power applied to the skin using the Mutzhas lamp is described as 150 W / m², which has no significant effect on skin temperature.

In addition to prior art UV treatment, dermatological procedures include lasers, including argon lasers, CCte lasers,

Nd (Yag) Lasers, Copper Gas Lasers, Ruby Lasers and Dye Lasers. For example, U.S. Patent No. 4,829,262 to Furumoto describes a method for constructing a dye laser for use in dermatological applications. The two skin conditions that can be treated with laser radiation are extracellular disorders, such as local differences in pigmentation or skin structure, sub-cutaneous cell disorders that cause various skin malformations, including port wine stain, uveitis, uveitis and spider tumors (cherry and spider angioma). Laser treatment of skin disorders usually involves local heating of the treatment area by adsorption of laser radiation. Skin heating changes or corrects skin disorders and results in the complete or partial elimination of skin abnormalities.

Certain external disorders, such as discoloration, can also be treated by heating the skin very quickly to a sufficiently high temperature to vaporize parts of the skin. Deeper cellular disorders are usually treated by heating blood to a temperature sufficiently high to cause it to clot. The malfunction will eventually disappear. A pulsating radiation source is often used to control the treatment depth. The depth at which heat penetrates the blood vessel is controlled by controlling the pulse width of the radiation source. The absorption and scattering coefficients of the skin also influence the penetration of heat. These coefficients are functions of the skin components and the wavelength of radiation. In particular, the absorption coefficient of light in the epidermis and the epidermis tends to be a slowly varying, monotonically decreasing function of wavelength. Thus, the wavelength of light should be chosen such that the absorption coefficient is optimized for the particular skin condition and vessel size being treated.

The effectiveness of lasers for applications such as tattoo removal, birthmark removal, or age tag removal is reduced because lasers are monochromatic. A laser of a certain wavelength can be effectively used to treat the first type of skin color disorders, but if the skin with the latter type of disorders does not effectively absorb the specific wavelength of the laser, it is ineffective for the latter type of skin disorders. Lasers are also usually complicated, expensive to manufacture, large in relation to the amount of power distributed, unreliable and difficult to maintain.

The wavelength of light also affects the treatment of cellular disorders, since the blood concentration in the immediate vicinity of the cellular disorders varies, and the concentration of the blood affects the absorption coefficient of the treatment area. Oxyhemoglobin is a major chromophore that controls the optical properties of blood and has a strong absorption band in the visible area. More specifically, the strongest absorption peak of oxyhemoglobin occurs at 418 nm and has a bandwidth of 60 nm. Two additional absorption peaks with lower absorption coefficients occur at 542 and 577 nm. The total bandwidth of these two peaks is in the order of 100 nm. In addition, light in the wavelength range 500 to 600 nm is desirable for treating skin vascular disorders because it is absorbed by the blood and penetrates the skin. Longer wavelengths up to 1000 nm are also effective because they can penetrate deeper into the skin, heat the surrounding tissue and, if the pulse width is long enough, influence the heating of the blood vessel as heat conduction. Longer wavelengths are also more effective in treating large diameter vessels because the lower absorption coefficient is compensated by the longer path of light in the vein.

According to it, a wider band electromagnetic radiation source, which covers the near-UV and visible part of the spectrum, should be desirable for external skin treatments for vascular disorders. The total wavelength range of the light source had to be sufficient to optimize therapy for any of a number of applications. Such a therapeutic electromagnetic radiation device should also be able to provide 110482 ground optimum wavelengths for a particular disorder being treated. The light intensity should be sufficient to cause the necessary thermal effect by raising the temperature of the treatment area to the desired temperature. Also, the pulse width should be varied over a wide enough range to achieve an optimum penetration depth for each application. Therefore, it is desirable to provide a light source having a wide range of wavelengths that can be selected according to the skin care required, with a controlled pulse width and high enough energy density for applications in the affected area.

Non-laser-type sources of pulsating light, such as linear flash10 lamps, offer these benefits. The intensity of the emitted light can be made high enough to achieve the required thermal effects. The pulse width may be varied to provide control of the depth of heat penetration. A typical spectrum covers the visible and ultraviolet regions, and the optical bands that are most effective for certain applications can be selected or added using fluorescent materials. In addition, non-laser light sources, such as flash lamps, are much simpler and easier to manufacture than lasers, are significantly cheaper for the same output power, and are potentially more efficient and reliable. They have a wide spectral range that can be optimized for many skin care applications. The pulse20 length of the sources can be varied over a wide range critical for different types of skin treatments.

In addition to being used to treat skin disorders, lasers have been used as an invasive medical method, such as crushing stones and removing thrombi. In such penetrating methods, laser light is coupled to the optical fibers and delivered through the fiber to the treatment area. In rock crushing, fiber supplies light from a pulsed laser to the kidney or gallstone, and the interaction of light with the stone produces a shock wave, which grinds the stone. To remove a blood clot, the light is plugged into the fiber and dissolves the blockage. In either case, the laser weaknesses discussed above with respect to laser skin care are present. According to it, a flash light treatment device for rock crushing and obstruction should be desirable.

To effectively treat the area, the light from the light source must be directed to the treatment area. The coupling of pulsed laser light to optical fibers is quite common in medical science. The prior art describes the coupling of isotropic, non-coherent point sources, such as CW lamps, to optical fibers. For example, U.S. Pat. No. 4,757,431, issued July 12, 1988 to Cross et al., Discloses a method for applying incoherent point sources to small filaments or arc lamps with a 2 mm separation of the electrode over a small area. Point sources (or small sources) are relatively easy to target without energy loss due to the small size of the sources. Also, U.S. Patent No. 4,022,534, issued May 10, 1977 to Kishner, discloses light produced by a flash tube and the collection of only small portions of light emitted by the tube into the optical fiber.

However, the large dimensions of an extended source, such as a flashlight, make it difficult to target large fractions of its energy over small areas. Coupling to optical fibers is even more difficult because not only does it have to provide high energy density, but also the angular distribution of light must be such that trapping in the optical fiber can be achieved. Thus, it is desirable to have a system for coupling the output of a high-intensity, extended, pulsed light source to an optical fiber.

Summary of the present invention

The features of the device according to the invention are apparent from the appended independent claim 1.

According to a first embodiment of the invention, the therapeutic care device comprises a body and an incoherent light source, suitably a flash lamp useful to provide a pulsating light output for treatment, disposed within the body. The body has an opening and is ideal for positioning next to the skin care area. The reflector is mounted inside the body near a light source and at least one optical filter is mounted near the body aperture. The iris is equally extensively attached to the opening. The power to the lamp is provided with a variable pulse width circuit. Thus, the treatment device provides a controlled density, filtered, pulsating, light output through an opening in the body to the skin for treatment.

According to another embodiment of the invention, the method of treatment with λ30 laser light comprises the steps of providing a high-energy pulsed light output from a non-laser, non-coherent light source and directing the pulsed light output to the treatment area. The width of the light output pulse is controlled and aligned so that the power density of the light is controlled. Light is also filtered to control the light spectrum.

According to a third embodiment of the invention, the switch comprises an incoherent light source, such as a rotating body-shaped flash lamp.

The reflector shall be positioned around an incoherent light source and at least one optical fiber or light guide. The fiber has a head placed inside the reflector. This head gathers light from a round lamp. In a similar coupling structure, fibers can be provided along with a linear, circular fiber transfer unit positioned to receive light from a light source and provide light to optical fibers. The cross-section of the reflector is elliptical in the plane of the linear flash tube, and the linear flash tube is located at one focal point of the ellipse while the transfer unit from linear to circular is located at the other focal point of the ellipse.

Preferred embodiments of the device according to the invention are apparent from the dependent claims 2 to 5.

Brief Description of the Drawings

For a better understanding of the invention, reference is made to the accompanying drawings, in which like numerals indicate like elements or parts throughout, and in which:

Fig. 1 is a cross-sectional view of an incoherent skin pulse light source treatment device;

Figure 2 is a side view of the light source of Figure 1;

Fig. 3 is a schematic diagram of a pulse forming network with a variable pulse width for use with the skin care device of Figs. 1 and 2;

Fig. 4 is a cross-sectional view of a switch for switching light from a rotating body shaped flash tube to an optical fiber at a conical edge;

Fig. 5 is a side view of a rotating body shaped flash tube;

Fig. 6 is a top view of a rotary tube shaped flash tube;

Figure 7 shows the geometry for connection to the conical portion; Fig. 8 is a cross-sectional view of a switch for switching light from a rotating body shaped flash tube to an optical fiber with a flat edge;

Fig. 9 is a front cross-sectional view of a switch for switching light from a linear flash tube to a circular fiber bundle;

Fig. 10 is a side cross-sectional view of the switch of Fig. 9;

Fig. 11 is a front view of a switch for switching light from a linear flash tube to an optical fiber; and

Fig. 12 is a front view of a switch for switching light from a linear flash tube to a doped optical fiber.

Various figures use like reference numerals to describe corresponding components.

Detailed Description of the Preferred Embodiment

Before describing in detail one or more embodiments of the invention, it is to be understood that the invention, in its application, is not limited to the details of the structure and the order of the components disclosed or described in the drawings. The invention is capable of other embodiments and can be practiced or implemented in many ways. It is also to be understood that the phraseology and terminology used herein are for purposes of description and should not be construed as limiting.

Referring now to Figures 1 and 2, there is shown an inconsistent skin pulse light source treatment device 10 constructed and operating in accordance with the principles of the present invention. The device 10 may be considered to comprise a body 12 having an opening, a handle 13 (Fig. 12 only), a light source 14 having an outer glass tube

15, an elliptical reflector 16, a set of optical filters 18, an iris 20, and a detector 22 (Figure 1 only).

The light source 14 attached to the body 12 may be a non-coherent light source, such as a gas-filled flash lamp, Model No. L5568, available from ILC. The light spectrum emitted by the gas-filled linear flash lamp is dependent on the current density, the type of glass envelope material and the gas mixture used in the tube. For high current densities (eg 3000 A / cm²) spectrum is similar to that of a black body. Typically, most of the energy is emitted in the wavelength range 300-1000 nm.

In order to treat skin (or visible) damage, the required light density must be directed at the skin. This luminance can be achieved by the alignment arrangement shown in Figures 1 and 2. Figure 1 shows a cross-sectional view of a reflector

16, also attached to body 12. As shown in Fig. 1, the reflector 16 has an ellipse in a plane perpendicular to the axis of the flash light 14. The linear flash lamp 14 is located at one focal point of the ellipse and the reflector 16 is disposed such that the skin treatment area 21 is located at another focal point. The arrangement shown is similar to the assembling arrangements used with the lasers and the light that is effectively connected to the skin from the flash lamp. However, this arrangement should not be considered restrictive. The elliptical reflector 16 may be a metallic reflector, usually polished aluminum, which is an easily workable reflector and has a very high reflectivity in the visible region, and a UV range of the spectrum can be used. Other bare or coated metals may also be used for this purpose.

Optical and neutral density filters 18 are fixed to the body near the treatment area and can be moved into or out of the beam to control the spectrum and intensity of light. Typically, 50-100 nm bandwidth filters are used as well as low pass filters in the spectral range and UV range. In some procedures, it is desirable to use most of the spectrum from which only the UV region is removed. In other applications, mainly for deeper penetration, it is preferable to use narrower bandwidths. Bandwidth filters and low pass filters are commercially available.

The glass tube 15 is concentric with the flash lamp 14 and is covered with fluorescent material. The glass tube 15 is typically used to treat blood vessel clots to optimize the energy efficiency of the device 10. The fluorescent material can be selected to absorb the flash lamp 14 in the UV region of the spectrum and produce light in the range of 500-650 nm optimized for absorption in the blood. Similar materials are coated on the inner walls of commercial fluorescent lamps. A typical material used to generate warm white light in fluorescent lamps has a conversion efficiency of 80%, has an emission peak at 570 nm and a bandwidth of 70 nm, and is useful for absorption in blood. The decay time of a few milliseconds for these phosphorus is consistent with the long pulses needed to treat blood vessels.

Other shapes and structures of the flash lamp 14, such as circular, helical, short arc and linear combination flash lamps, may be used. The reflector 16 may have other structures, such as parabolic or circular reflectors. The light source can also be used without a reflector and the required energy and power density can be achieved by placing the light source 14 in the vicinity of the treatment area.

The iris 20 is attached to the body 12 between the optical filters 18 and the treatment area and controls the length and width of the treatment area, i.e. by aligning the output of the flash lamp 14. The length of the flash lamp 14 controls the maximum length that can be exposed. Typically, a tube 8 cm long (arc length) is used and only the center 5 cm of the tube is exposed. The use of a 5 cm center section ensures a high degree of energy density in the exposed area. Thus, in this embodiment, the iris 20 (also called a collimator) allows exposure of skin areas up to a maximum length of 5 cm. Iris

20 can be closed to give a minimum exposure of one millimeter. Correspondingly, the width of the exposed skin area can be controlled in the 1-5 mm range for a 5 mm wide flash lamp. Larger treatment areas can easily be achieved by using longer flash tubes or composite tubes, and smaller areas of exposure are observed with an iris that more fully assembles the beam. The present invention provides a larger field of exposure compared to prior art lasers or point sources and is highly effective in coagulating blood vessels because interruption of blood flow over a long portion of the vessel is more effective in coagulating it. At the same time, the wider exposed area reduces the time required for the procedure.

The detector 22 (Fig. 1) is mounted on the outside of the body 12 and accurately shines the light reflected from the skin. The detector 22 coupled to the optical filters 18 and the neutral density filters can be used to provide a quick estimate of the spectral reflection and skin absorption coefficients. This can be accomplished at a low energy density level before using the main treatment pulse. Measurement of the optical properties of the skin prior to use of the main pulse is useful for determining optical treatment conditions. As noted above, the broad spectrum of light emitted from a non-laser-type source allows for skin-wide examination of the skin and selection of optimal treatment wavelengths.

In an alternative embodiment, the detector 22 and the second detector system can be used for real-time skin temperature measurement when exposed to a pulsing light source. This is useful in sctermoanalytical applications with long pulses in which light is absorbed into the epidermis or epidermis. When the outer portion of the epidermis rises to too high 32, it can result in permanent skin scarring. Thus, skin temperature should be measured. This can be detected by using infrared emission of heated skin to prevent skin overexposure.

A typical real-time detector system would measure the infrared emission of the skin at two specific wavelengths using two detectors and filters. The ratio between the signals of the two detectors can be used to estimate the instantaneous skin temperature. The pulsating light source can be stopped if a preselected skin temperature is reached. This measurement is relatively easy because the temperature threshold for heart rate heating, which can cause scarring of the skin, is of the order of 50 ° C or more, which is easily measured using infrared emission.

The depth of heat penetration depends on the absorption of light and the si5 shore on different layers and the thermal properties of the skin. Another important parameter is pulse width. For a source of pulsating light from the energy absorbed into the infinitesimal thin layer, the depth (d) of thermal infiltration during the pulse due to thermal conduction can be written as shown in equation 1:

(equation 1) d = 4 [kA t / C_p]^1/2 where k = thermal conductivity of the material to be irradiated

At = pulse width of the light pulse;

C = thermal capacity of the material; p = density of material.

It is clear from Equation 1 that the penetration depth of the heat can be controlled by the pulse width of the light source. Thus, pulse width variation 10 '⁵ s

-10’¹ s leads to a variation in thermal penetration by a factor of 100.

Accordingly, the flash lamp 14 gives a pulse width 10 '⁵ s 10 '¹ For treating vascular disorders in which the blood vessels of the skin are targeted, the pulse length is selected to uniformly heat the entire vessel thickness as much as possible to achieve effective coagulation.

Typical blood vessels to be treated in the skin have thicknesses within 0.5 mm. Thus, the optimum pulse width, including the thermal properties of the blood, is in the order of 100 ms. If shorter pulses are used, the heat still passes through the blood causing coagulation, but the instantaneous temperature in some of the vessel blood and the surrounding tissue is, however, higher than the temperature required for coagulation and can cause unwanted damage.

A very short pulse is used to treat external skin disorders in which skin vaporization is the target to provide very low thermal penetration. For example, 10 '⁵ s pulse penetrates (thermal conductivity) to a depth of the order of 5 microns in the skin. Thus, only a thin layer of skin is heated and a very high, instantaneous temperature is detected so that the external mark on the skin is vaporized.

Figure 3 shows a variable pulse width generating circuit comprising a plurality of individual pulse generating networks (PFNs) which generate the variable pulse widths of the flash lamp 14. The half-width (FWHM) of the light pulse of the flash lamp, which is controlled by a single element PFN of capacitance C and inductance L, is approximately equal to:

(equation 2) At «2 [LC]^1/2

The flash lamp 14 can be driven by three different PFNs as shown in Fig. 10a 3. Relay contacts R1 ', R2¹ and R3 'is used to select three capacitors C1, C2 and C3 charged by the high voltage source. The relays R1, R2 and R3 are used to select the PFN to be connected to the flash lamp 14. The high voltage switches S1, S2 and S3 are used to discharge the energy stored in the PFN capacitor, the flash lamp 14. In one embodiment, L1, L3 and L2 The values ​​of n are 100 mH, 1 mH and 5 mH, respectively, and those of C1, C2 and C3 are 100 mF, 1 mF and 10 mF, respectively.

In addition to the possibility of triggering each PFN individually, which produces a pulse width variation, further variation can be achieved by triggering the PFNs periodically. For example, if two are triggered

PFNs having pulse widths Δt1 and Δt2, such that the second PFN is triggered after the first pulse has split in half its amplitude, are then given the effective pulse width of the light of the operation of this system at: Δt1 and Δt1 + At2.

The charging power supply voltage is typically in the range of 500 V to 5 kV. Therefore, relays should be high voltage relays that can reliably isolate these voltages. The switches S are capable of driving the current of the flash lamp 14 and isolating the high reverse voltage generated if the PFNs are triggered periodically. Solid state switches, vacuum switches or gas switches may be used for this purpose.

The pre-annealing power source (not shown in Figure 3) can be used to hold the flash lamp in a low current conduction mode. Other structures may be used to provide pulse width variations, such as the use of a single PFN and the use of a fork switch, or the use of a switch with closing and opening capabilities.

Typically for operation of a flash lamp with an electrical pulse width

- A linear electric energy density input of 100 110482 can be used for 10 ms

300 J / cm. An energy density of 30 to 100 J / cm can be achieved on the skin with a typical internal diameter of a flash lamp of 5 mm. Using bandwidths of 500 to 650 nm transfers 20% of the incoming energy. In this way the skin has an energy density of 6 to 20 J / cm². Incorporation of fluorescent material extends further the exposure output in the desired region, allowing the same irradiation to the skin with lower energy input to the flash lamp 14.

Heart rate laser treatment on the skin shows energy densities of 0.5 to 10 J / cm² pulse widths within 0.5 ms are usually effective in treating vascular related disorders. The parameter range is in the range of operation of non-laser type pulsing light sources, such as a linear flash lamp. A few steps of neutral glass density filters 18 can be used to control the skin's energy density.

For external interference, a pulse width of 5 ms is typically used. An input of 20 J / cm of electrical energy into a 5 mm light bulb with an inner diameter leads to a skin of 10 J / cm². Breaking the hard UV portion of the spectrum results in 90% energy transfer or skin exposure at an energy density close to 10 J / cm². This energy density is high enough to vaporize external marks on the skin.

The device 10 can be provided in two units: a lightweight unit 20 held by a physician using a handle 13, a hand held unit comprising a flash lamp 14, filters 18, and an iris 20 which collectively control the spectrum and exposed area size and detectors that measure reflectivity and skin moment. The power supply, PFNs, and electrical controls are included in a separate box (not shown) that is connected to a handheld unit via a flexible cable. This allows for easy operation and easy access to the skin area that needs to be treated.

The invention has hitherto been described in the context of skin care. However, the use of flash light rather than laser in penetrating therapies also offers benefits. Procedures such as rock crushing or removal of blood vessel cortex can be performed with a flash lamp. Such a device may be similar to that shown in Figures 1 and 2, and may use the electronics of Figure 3 to produce a flash. However, a number of switches 40, 80 and 90 are shown in Figures 4 and 8 to 10 for proper light coupling to the optical fiber.

The switch 40 comprises a high intensity, incoherent, and isotropic pulsating light from the optical source, such as a linear flash tube 42, a light reflector 44 which distributes the light energy to the optical fiber 46. The latter usually has a conical edge in the embodiment of Figure 4. Optical fiber 46 transmits light from the light collector system 44 to the treatment area. Usually, the switch 40 switches the pulsating light from the flash tube to the optical fiber and has applications in the medical, industrial, and household fields.

For example, the switch 40 may be used to rapidly heat or remove a material portion to be treated or to induce a photochemical process in material handling. Alternatively, the switch 40 may be used in a photographic application to provide a flash to capture an image. Using such a switch would allow the flash bulb to be inserted inside the camera as light travels outside the camera using optical fiber. As one of ordinary skill in the art should recognize, switch 40 permits the use of incoherent light in many applications that have previously used coherent or incoherent light.

In order to provide light coupling to the optical fiber, the flash tube 42 is in the form of a rotating body, shown in Figures 5 and 6, and is disposed within the reflector 44. In addition to the shape of the rotary piece, other shapes, such as continuous thread, may be used on the flash tube 42. However, a helical tube is more difficult to manufacture than a rotary tube shaped tube.

Referring now to Fig. 6, the flash tube 42 is generally twisted but not fully twisted since the electrodes located at the ends of the threads must be connected to a power source. This does not cause significant interference with the circular shaped flash tube 42, since the electrode coupling can be made quite small.

The reflector 44 collects and concentrates the light and has a cross-section approximately in the form of an ellipse in a plane perpendicular to the minor axis of the rotary tube-shaped flash tube 42. The main axis of this ellipse preferably forms a small angle with the main axis of the rotating body 42 lamp. The exact value of the angle between the axis of the ellipse and the main axis of the lamp 42 is dependent on the numerical opening angle (NA) of the optical fiber. The rotary tube-shaped flash tube is positioned so that its minor axis coincides with the focal point of the ellipse. The second focal point of the ellipse is at the edge of the optical fiber 46. The reflector 44 can be machined with the metal surfaces polished for good reflection. Aluminum is a very good reflector with high reflectivity in the visible and ultraviolet regions and can be used for this purpose. The reflector can be machined in one piece and then cut off along a surface perpendicular to the main axis of the device. This allows the rotary tube-shaped flash tube to be connected to the device.

As shown in Fig. 4, the optical fiber 46 has a cone with a small opening angle, so that the total area of ​​the fiber exposed by the flash tube increases. Referring now to Fig. 7, the geometry for coupling light to a conical tip is shown. Here, it is assumed that light comes from an area with a refractive index of n₂ and that the refractive index of the conical region of the fiber (as well as the rest of the fiber core) is ni.

Not all the rays of light that hit the cone are trapped there. For Va10 beams propagating in a plane containing the main axis of the system, a condition can be derived for the angle of the beam that is trapped and absorbed into the fiber. This condition is illustrated in Figure 3.

sin (pkriitt) = Cos (p) - [ni²/of₂² -1]^1/2 sin (p) (equation 3)

Light is trapped in the conical portion of the optical fiber if the incident angle μ is greater than the critical value calculated from equation 3. Trapping is only possible if ni> n₂. If the medium outside the fiber is air, Π2 =

1. Also, not all light trapped in the conical portion of the fiber is trapped in the direct portion of the fiber if a fiber having a core and a protective envelope is used. If a fiber with a core and not a sheath (air sheath) is used, all the rays caught in the conical portion of the fiber will also be trapped in the direct portion of the fiber.

The hardware configuration shown in Figure 4 can also be used to fill the space between the reflector and the optical fiber. Water can be a very suitable liquid for this purpose. Water is also very effective at cooling the flash lamp at high repetition rate pulses. The presence of liquid reduces the losses associated with the glass-to-air transition, such as the transition between the material of the flash lamp and the air. If the fluid is used in the volume of the reflector, then its refractive index can then be chosen such that all beams trapped in the conical portion will also trap the fiber, even when core / sheathed fibers are used.

Another way to assemble the fiber in the reflector is to use a flat-edged fiber. This hardware configuration is shown in Fig. 8 and has a trap 35 efficiency very close to that of a conical edge.

Many other fiber edge shapes, such as spherical shapes, can also be used. The fiber edge configuration also has an effect on the distribution of light outside the fiber and can be selected according to the particular application of the device.

The device can be used with a variety of optical fibers. A single or small number of millimeter-diameter or more-millimeter fibers are typically used in penetrating medical applications. In other applications, particularly industrial and household applications, it may be more advantageous to use a fiber having a larger diameter or a larger fiber bundle or light guide.

Figures 9 and 10 show a switch 90 for engaging a linear flash tube 10 through a linear circular fiber transfer unit 94 to a fiber bundle 96. The reflector 98 has an elliptical cross-section, shown in Figure 10, in the axial plane of the linear flash tube 92 in this embodiment. The tube 92 is located at the second focal point of the ellipse while the linear side of the linear to round bundle converter 92 is located at the second focal point of the ellipse. This hardware configuration is relatively easy to manufacture and can use commercially available linear to round converters such as 25-004-4 available from General Fiber Optics. This hardware configuration is particularly useful for larger fiber exposures or for flash lighting purposes.

The energy and power densities that can be achieved by the present invention are high enough to produce the desired effects on surface treatment or medical applications. For the embodiment shown in Figure 4, the total energy and power densities can be estimated as follows. For a typical rotating bulb with an inside diameter of 4 mm and a main diameter

3.3 cm, a linear electrical energy density input to a 10 J / cm lamp with a 5 με pulse width can be used. The light output from the lamp is 5 - 6 J / cm for optimum electrical operating conditions. For the reflector shown in Figure 4, 50% of the light generated by the lamp reaches the lower focal point. Thus, a total energy flow of 25-30 J / cm at the focal point can be observed. For the embodiments shown in Figure 4 or Figure 8, or in the overall cross-sectional area of ​​the reflector, the focal plane has a cross-section of 0.8 cm². Energy densities in the order of 30-40 J / cm² at the fiber inlet, should be achieved by this cross-section. This corresponds to a power density of 5-10 MW / cm², which are typical power densities used in medical or material handling applications.

For longer pulses, higher linear electrical energy densities can be used. For a 1 ms pulse, a linear electric energy density of 100 J / cm can be applied to the flash tube. The corresponding energy density for the fuel would be up to 300 J / cm. Such energy densities are highly effective in industrial cleaning and treatment applications as well as in medical applications.

Alternative embodiments for connecting optical fibers to an expanded light source, such as a linear flash lamp, are shown in Figures 11 and 12. In the embodiment of Figure 11, optical fiber 101 is wrapped around lamp 102 and lamp housing 103. Some of the light generated by the light source is coupled to the fiber. If the light rays propagate in the direction in which the fiber traps 10, then this light propagates in the fiber and can be used at the fiber exit 104. One limitation of this assembly is the fact that most of the light emitted by the lamp is traveling in a direction perpendicular to the lamp surface 103 and cannot trap the fiber 101.

The embodiment shown in Fig. 12 addresses this problem.

The doped optical fiber 105 is wrapped around the lamp 102 and the sheath 103 rather than the unalloyed fiber 101 of Figure 11. This light radiates omnidirectionally and that portion of what is inside the critical angle of fiber 105 is trapped and propagated through the fiber and can be used at the outlet of fiber 104. The angle of light trapped in the fiber is the critical angle of the material from which the optical fiber or optical waveguide is made. For airborne fiber (or optical waveguide), this angle is given as sin «. = 1 / n.

Typically for glass or other transparent materials, n = 1.5 and a =

41.8 °. This corresponds to a trapping efficiency of more than 10% of the light emitted from the fluorescence within the fiber. Assuming a fluorescence process efficiency of 50%, it is found that more than 5% of the light produced by the lamp is trapped and propagated to the fiber. For example, a 4 (10.16 cm) bulb with a linear electrical energy input of 300 J / inch (about 118 J / cm) and 50% conversion efficiency of six of the electricity would light 2.5% of its electrical energy into the fiber. This corresponds to a total energy of 30 J for a 4 (10.16 cm) lamp. This embodiment has the additional advantage of transmitting the wavelength emitted by the lamp to a wavelength which may be more useful in some of the therapeutic or treatment applications mentioned earlier. Thus, the fluorescent material doped into the fiber can be selected according to the emission wavelength determined by the particular applications of the device.

Thus, it will be apparent that a flash lamp and a switch are provided in accordance with the present invention that fully meet the objects and advantages set forth above. Although the invention has been described in connection with their particular embodiments, it will be apparent that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to encompass such alternatives, modifications, and variations within the spirit and wide scope of the appended claims.