JPH0457066B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates generally to arc lamps, and more particularly to arc lamps used with optical fiber bundles.

B. Description of conventional type Arc lamps are used to obtain a concentrated point light source for use in instruments, projection, etc., and endoscopes in the medical field are one example of their use. In endoscopes, arc lamps serve as the illumination source for the fiber optic bundle. This illumination source allows the body's canals and adjacent organs to be visually examined without the need for traditional surgery. Arc lamps are also used in industrial endoscopes to inspect structures and components that are difficult to see with the naked eye, such as the interior of jet engines.

A typical known type of arc lamp system for use with a fiber optic bundle is shown in FIG. This known form is generally designated by the reference numeral 10. The arc lamp 20 is approximately symmetrical about an axis 22, and includes a base 24, a body 26, an anode 28, and a cathode 3.
0, a plurality of cathode holding arcs 32, and a window member 34. Base 24 is generally made of iron. Body 26 is typically made of ceramic material.

Body 26 has a concave cavity 40 that defines a reflective curved surface 42 . Reflection curved surface 4
2 has a reflective metal coating.
The anode 28 passes from the base 24 through the body 26,
A space 4 is formed along the axis 22 from behind the reflective curved surface 42.
Extends into 0. Cathode support arm 32 extends radially from body 26 toward axis 22 . The cathode 30 is attached to the holding arm 3 along the axis 22.
It is attached to 2. Since the window 34 is a seal fit to the body 26, the cavity 40 is airtight. Window 34 is made of transparent material. In use, the cavity 40 is filled with an inert gas, for example xenon, at a pressure several times atmospheric pressure. In arc lamps, the breakdown voltage passes through the arc gap,
As a result, light is emitted as the illuminating electron current (ie, arc discharge) passes through the gap from the anode 30 to the cathode 28. This form of arc lamp typically has approximately
Operates in the range of 150 watts to 800 watts.

A first cooling block 50 is attached to the base 24. Cooling block 50 absorbs heat from base 24. The second cooling block 52
The heat generated within the window 34 is absorbed.

Light 60 exits arc lamp 20 and passes through lens 64. Lens 64 is necessary to focus light 60 into a beam narrow enough for use with optical fiber bundle 68. Light 60 is fiber bundle 6
8, it is filtered by a normal temperature mirror 70. The normal temperature mirror 70 transforms the visible light 74 into a fiber bundle 68
The infrared rays are reflected to the third cooling block 80, but the infrared rays are passed through. Cooling block 80 dissipates the heat of infrared light 76.

There are several problems with the above-mentioned known types of systems. One problem is that this system is bulky and has many components. Another problem is that, for example, the reflective curved surface 4
2 and other components include a cathode 30 and a lens 6.
4. It must be accurately positioned with respect to the mirror 70. Even the slightest misalignment of these components can have serious consequences. Yet another problem is that reflective surfaces create holes within the light beam. Such holes within the beam prevent the generation of a uniform light source.

C. Summary of the Invention Therefore, an object of the present invention is to obtain an optical fiber arc lamp of compact size.

A further object of the invention is to provide an optical fiber arc lamp that does not require the use of reflectors.

Yet another object of the present invention is to provide a fiber optic arc lamp that does not produce a pattern of holes in the light beam.

It is a further object of the present invention to provide an arc lamp capable of projecting a broad spectrum point source of light energy into a fiber optic light guiding bundle having a diameter of 50 microns or more.

It is a further object of the present invention to provide a fiber optic arc lamp in which the plasma of the arc is reflected directly into the light guiding conductor without intervening reflectors.

Another object of the invention is to provide a fiber optic arc lamp with improved spatial characteristics by providing a small diameter light guide in close proximity to the light source to directly reflect the arc. The diameter of the light guide can then be adapted to the size of the plasma arc.

Briefly, one preferred embodiment of the invention includes a ceramic body with a cylindrical cavity containing high pressure gas. A cathode is mounted to extend through the first end of the body coaxially with the axis of the cylindrical cavity. The cathode also has a rod shape with a tapered end and a pointed tip. This distal end extends into the cavity. An anode is mounted to extend through the second end of the body and extends coaxially with the axis of the cylindrical cavity. This anode is a hollow cylinder. The distal end of the anode extends into the cavity and has an end cap. The tapered end of the cathode and the end cap of the anode form an arc gap. The anode end cap has a hole.

A cylindrical sapphire light tube is sized to fit inside the hollow anode and exits from inside the cavity to the outside of the body. Light from the arc gap passes through a hole in the anode and reaches a Saphire condenser tube. The condenser tube has a hemispherical end opposite to the hole;
Light is collected. The light is focused onto an optical fiber bundle outside the body.

An advantage of the present invention is that it provides a fiber optic arc lamp that is compact in size.

A further advantage of the invention is that it does not require the use of reflectors.

Yet another advantage of the present invention is that it does not produce the beam hole pattern that is characteristic of arc lamps using reflective optics.

Another advantage of the present invention is that a broad spectrum light energy point source can be projected into the light guide bundle of optical fibers with characteristic diameters of 50 microns or more.

A further advantage of the invention is that the plasma of the arc is reflected directly into the light guiding conductor without intervening reflectors.

Yet another advantage of the present invention is that by locating a small diameter light guide in close proximity to the light source and directly reflecting the arc, space properties are improved; , the diameter of the light guide can be matched to the size of the plasma arc.

A further advantage of the present invention is that the Sapphire condenser tube directs the light into very small diameter fiber bundles (size 50
The point is that it has an exit with a radius of curvature that allows the light to be focused within a micron.

The foregoing objects and advantages of the present invention will no doubt become apparent to those skilled in the art after reading the following description of the preferred embodiments illustrated in the accompanying drawings.

D. Detailed Description of Preferred Embodiments FIG. 2 shows an arc discharge tube 100 of the present invention. The body 106 includes a ceramic cylinder 108 having an axis 109 and a cathode inner ring 11.
0, cathode backup ring 112, anode inner ring 114, anode backup ring 116
It consists of The inner rings 110, 114 are made of Kovar material and the ends of the ceramic cylinder 108 are copper brazed. Backup rings 112, 116 are made of ceramic material. Ring 112 is inner ring 1
10, and ring 116 is copper-brazed to ring 1.
14 is copper brazed. Airtight space 118
is formed by an inner cylindrical body 108.

The cathode holder 120 has a hole 122 in the ring 112.
and the hole 124 of the ring 110 coaxially with the axis 109 . The holder 120 is a nickel tube. The holding body 120 has a hole 124 in diameter.
Portion 130 larger but smaller than hole 122
and a portion 132 having a diameter approximately equal to the hole 124.
Edge portion 132 extends into cavity 118. The retainer 120 is brazed to the inner ring 110 with copper or silver. A pair of gas holes 136, 138
extends perpendicularly through portion 132 of retainer 120 and intersects the inner surface of retainer 120. The inner surface of holder 120 defines a flow path 146 .

The cathode 150 is attached to the holder 1 coaxially with the axis 109.
It extends from 20. The cathode 150 is rod-shaped and is partially fitted into the inner passageway 146. The cathode 150 is made of tungsten and the holder 1
It is brazed to 20. The distal end of the cathode tapers at an angle of approximately 50 degrees to axis 109 and is pointed.

Tab 156 is copper brazed to cathode holder 120. The tab 156 also has a hole 158 at one end.
It is a flat steel strip with a hole 1
58 is sized to receive portion 130 of cathode holder 120. Tab 156 projects from the outer edge of backup ring 112 and extends perpendicular to axis 109.

The anode holder 170 has a hole 172 in the ring 116.
and the hole 174 of the ring 114, and the axis 10
It extends coaxially with 9. The holding body 170 is formed with an internal passage 176 and a cut-out portion 178. Further, the holding body 170 has holes 17
Anode portion 180 having a diameter approximately equal to 2,174
and a threaded portion 1 having a larger diameter than the anode portion 180.
82 and a rear portion 1 having a smaller diameter than the anode portion 180.
84, and is soldered to the inner ring 114 with copper or silver.

The anode 190 is made of tungsten and the inner passage 19
It has a shape similar to a hollow cylinder with 2.
Passage 192 has the same diameter as passage 176 in retainer 170 . The anode 190 has a holding portion 19 having approximately the same diameter as the cutout portion 178 of the holding body 170.
It has 4. Further, the anode 190 is arranged coaxially with the axis 109 with a holding portion 194 partially fitted inside the cut-out portion 178 . Furthermore, the anode 190 is attached to the holder 1
70 and has an arc area 196 that is larger in diameter than the retaining portion 194.
Anode 190 also has an end cap 198 at the end of arc area 196. Hole 200 extends through end cap 198 coaxially with axis 109 . Hole 200 has a diameter smaller than the diameter of passageway 192. Passageway 192 tapers at a 45 degree angle to axis 109 to match bore 200 .

Cooling block 220 is cylindrical in shape and has a plurality of fins 222 extending radially outwardly from the cylindrical portion. cooling block 220
is made of aluminum and is arranged coaxially with the axis 109. Internal passageway 224 is symmetrical about axis 109. Cutout 226 allows cooling block 220 to fit around the outer edge of backup ring 116. The threaded portion 228 of the passageway 224 is connected to the retainer 170.
is engaged with the threaded portion 182 of. Portion 230 of passageway 224 has a diameter approximately equal to the diameter of rear portion 184 of retainer 170 so that portion 230 of passage 224
fits into the inner portion 230. A filter portion 236 of the passageway 224 is disposed coaxially with the axis 109 rearwardly of the inner portion 230 and
It has a larger diameter. The connecting threaded portion 238 of the passage 224 is arranged coaxially with the axis 109 behind the filter portion 236 .

The heat absorption filter 242 is connected to the cooling block 220.
is located in the inner portion 236 of the . Filter 2
42 is disk-shaped and made of glass. The cylindrical fiber optic connector 250 is connected to the cooling block 22.
It has a threaded portion 252 that mates with threaded portion 238 of 0. Connector 250 has a threaded portion 254 that engages the optical fiber bundle and also has axis 1
It has an internal passage 256 that is symmetrical about 09. This internal passage 256 is connected to the anode holder 17.
It has approximately the same diameter as the passage 176 at 0.
A pair of slots 258 are formed in the passageway 256 at the outer end of the threaded portion 254 that mates with the optical fiber bundle. Connector 250 is made of aluminum.

A cylindrical sapphire condenser tube 270 is disposed within the passage 176 of the holder 170 and the passage 192 of the anode 190. The diameter of condenser tube 270 is approximately equal to the diameter of passageways 176,192. Concentrator tube 270 must be long enough to allow heat from anode 190 to dissipate before reaching fiber optic bundle connector 250. Further, the condenser tube 270 has a curved surface 272 at one end so that light can be condensed. Furthermore, a second curved surface 274 may be provided at the other end to collect light.

FIG. 3 shows an air gap portion 300 of arc discharge tube 100. The cathode 150 is
It has a diameter of 0.0813 cm and hole 200 has a diameter of 0.0787 cm. From the tip of the cathode 150 to the anode 19
The air gap 310 to 0 is 0.051cm,
The depth of hole 200 extends by a depth 312 of 0.0381 cm.

In operation, the cavity 118 is filled with 17 atmospheres of xenon gas through the passageway 146 of the cathode carrier 120. Passageway 146 is then sealed.
Light is generated when the breakdown voltage exceeds arc gap 310. Typical breakdown voltage is 25,000 volts. Electron flow across the gap from cathode 150 to anode 190 creates a conical arc discharge or plasma 320. This conical arc discharge 320 causes a flow of light through the internal passageway 192 of the anode 190. The hole 200 has the role of guiding light.

A condenser tube 270 is disposed within the passageway 192 and collects the light 3
24 passes through its end face 272. The end surface 272 has a curved surface, and the condenser tube 27
0 and filter 242 to the fiber bundle held within fiber optic bundle connector 250 is focused. Filter 242 absorbs infrared heat and dissipates this heat through cooling block 220. The curved surface 274 also focuses the light so that the light can be focused into a very small diameter optical fiber bundle (50 microns in size).

The present invention eliminates the need for bulky reflectors to collect light because the collection tube 270 is located close to the arc gap 310. The unique placement of the condenser tube 270 within the anode 190 allows extremely efficient use of the light generated by the conical arc discharge 320.

FIG. 4 shows a cross section of an arc discharge where light is concentratedly distributed. Each line represents constant luminous intensity per square millimeter measured in candelas. Curved surface 272 focuses the hottest and most concentrated arc light area. This light range is cathode 150
is a point 410 at the tip of .

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art having read the above disclosure that various alternatives and variations are possible. It is therefore intended that the appended claims cover all alternatives and modifications falling within the true spirit and scope of the invention.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a known type of arc lamp;
Figure 3 is a cross-sectional view of an arc discharge tube according to the present invention.
The figure is an enlarged cross-sectional view of a part of the discharge tube in Figure 2,
The figure is a cross-sectional view showing the degree of concentration of light from arc discharge. In the figure, 100... arc discharge tube, 106
... Body, 146 ... Internal passage, 150 ... Cathode, 190 ... Anode, 220 ... Cooling block,
242...Filter, 250...Optical fiber bundle connector, 270...Safyaiya condenser tube, 272,
274... Condensing curved surface.

Claims (1)

[Claims] 1. In an arc discharge tube, this discharge tube has a body 106 made of an opaque dielectric material, and a cavity 118 in which high-pressure gas is sealed is formed inside the body. It also has a pair of electrodes 150, 190, which are assembled in the cavity 118, with the ends of the electrodes 150, 190 spaced apart to form an air gap 310. Furthermore, there is a cylindrical condenser tube 270 made of Saffire.
The light condensing tube is installed so as to penetrate the body wall from the outside of the body 106 and reach into the cavity 118, and the first end 272 of the light condensing tube 270 is attached to the arc gap 310
said cavity 118 to focus the arc discharge of
An arc discharge tube having a curved surface located within the body and also having a second end 274 located outside the body 106. 2. One of the electrodes 150, 190 is a rod-shaped cathode member 150, which is attached to the body wall, and has a tapered end and a sharp tip; This anode member 190 is attached to the body wall and is a hollow cylindrical body sized to fit over the first end of the Saphire condenser tube 270. is formed with an end cap 198 having a hole 200 that allows the light of the arc discharge to pass to a sapphire concentrator tube 270, and further includes an anode 1.
2. The discharge tube of claim 1, wherein an end cap 198 of the cathode 150 forms an arc gap 310 with said tip of the cathode 150. 3 Electrodes 150, 190 and Saphire condenser tube 2
70. The discharge tube according to claim 1, wherein the discharge tube is disposed coaxially with the axis 109. 4 The heat absorption filter 242 is the second
2. Discharge tube according to claim 1, characterized in that it is arranged at the end 274. 5. The discharge tube according to claim 4, characterized in that a cooling block 220 is added to the body 106 and the filter 242. 6 Optical fiber bundle connector 250 connects to cooling block 2
6. The discharge tube according to claim 5, further comprising a saphire light condenser tube 270 which is attached to the second end portion 20 and arranged at a position to receive light from the second end portion 274. 7. In the arc discharge tube, the discharge tube has a cylindrical body 106 made of dielectric material, which body 106 has a cavity 118 symmetrical about an axis 109, in which cavity 118 is formed. The cavity 118 is filled with high pressure gas and has a cathode 150 assembled at a first end of the cavity 118 .
extends into the cavity 118 coaxially with the axis 109 and has a tapered distal end and also has an anode 190 assembled at a second end of the cavity 118, with the axis This anode 1 extends coaxially with 109 into the cavity 118.
90 is a hollow cylinder having an internal passageway 192 extending outwardly from the body 106 and the end cap 198 of the anode end, and a hole 200 extending within the end cap 198 along axis 109.
The anode end and the cathode are spaced apart from each other, forming an arc gap, and further includes a cylindrical sapphire condenser tube 270. A condenser tube is disposed within the passageway 192 coaxially with the axis 109 and has a curved surface at a first end 272 opposite the bore 200 so that the discharge of the arc gap 310 The light travels along the condenser tube 270 at its second end 2
An arc discharge tube characterized in that the light passes through 74 and is concentrated at a light point outside the body. 8 The metal cooling block 220 is connected to the body 10.
7. Appended to the anode section extending through the second end of the body on the outside of the body, the anode section has a passageway 224 for receiving a condenser tube 270. discharge tube. 9 The heat absorption filter 242 is connected to the second end portion 2 of the condenser tube.
9. The discharge tube of claim 8, wherein the discharge tube is disposed in the cooling block passage 224 near the discharge tube 74 to absorb heat. 10 The optical fiber bundle connector 250 is connected to the body 10
6 and the position of this connector 250 is such that the optical fiber bundle held within the connector is connected to the condenser tube 270.
8. The discharge tube according to claim 7, wherein the light spot is located at a position where light from the source can be received. 11 The diameter of the internal passage 192 of the anode is the same as that of the hole 200.
8. The discharge vessel of claim 7, wherein the internal passageway (192) has a tapered portion which coincides with the bore (200). 12. The discharge tube according to claim 7, wherein the second end 274 of the cylindrical condenser tube 270 has a curved surface to further concentrate the light.