Liquid light guide with position holding function

Abstract

Lighting device with a radiation source (11) and a liquid light guide (10) coupled thereto, which has a liquid-filled light guide tube (28), characterized in that the liquid light guide (10) further comprises a position-holding tube (22) made of a flexible metal which holds the bending position and within which the light guide tube (28) is arranged, the optical fiber tube (28) is firmly connected at at least one end to a sealing end piece (14; 24), the position-holding hose (22) is fixedly connected at at least one end to a tubular element (13; 23) in which the end piece (14; 24) is rotatably mounted, and the at least one end of the optical fiber tube (28) is rotatably mounted relative to the position-holding tube (22) by a connecting element (15; 25) which rotatably connects the end piece (14; 24) at the at least one end of the optical fiber tube (28) to the tube element (13; 23) on the position-holding tube (22).

Description

[0001] The invention relates to a lighting device comprising a radiation source and a liquid light guide connected to it. The liquid light guide has a flexible position-holding tube that can be manually aligned with an object to be illuminated and subsequently maintains its spatial position.

[0002] Such lighting devices are known in the prior art in connection with fiber optic bundles and are widely used in laboratories (see, for example, CH 635 944 A5). They are also referred to as light sources with "gooseneck" light guides and typically consist of a radiation source with a tungsten / halogen reflector lamp and one (or more) fiber optic bundle light guides housed in a flexible armoring tube with a position-holding function. The well-known gooseneck light guides have a total length of less than one meter, which is sufficient for most applications. The outer armoring tubes, also known as holding tubes, are commercially available and are wound from a metallic profile strip with sealing thread or sealing wire, with a special technology ensuring the holding function after bending.

[0003] DE 32 25 452 A1 discloses another example of a conventional fiber optic light guide - but without position holding function

[0004] Since fiber optic bundles are highly flexible, and the beginning and end of a fiber optic bundle can easily be twisted together, the production of a gooseneck fiber optic cable simply requires inserting the fiber bundle into the holding tube and firmly gluing the respective end pieces of the fiber optic bundle to the holding tube at the beginning and end. If such a gooseneck fiber optic cable is then fixed to the radiation source at one end, the other end can be freely manipulated. Due to its high internal flexibility, the fiber optic bundle inside the holding tube can absorb changes in the relative position between the fiber optic cable and the radiation source caused by manipulation, without causing tension in the fiber bundle and risking fiber optic breakage.

[0005] Liquid light guides, such as those described in DE 42 33 087 A1, have been on the market for over 30 years and offer the advantage of better optical transmission in the short-wavelength visible spectrum and in the UV range compared to fiber optic bundles. This is particularly useful for certain laboratory applications, such as fluorescence excitation with short-wavelength radiation. DE 299 17 914 U1 discloses another example of a conventional liquid light guide.

[0006] A gooseneck light guide arrangement would also be desirable for this application. Liquid light guides contain a liquid-filled fluorocarbon tube (FC tube), also known as the "light guide core," which is sealed at both ends by glass plugs and mechanical sealing sleeves. Unlike highly flexible fiber optic bundles, liquid light guides are only semi-flexible, and the two ends of a liquid light guide cannot be twisted together. These mechanical disadvantages of a liquid light guide become increasingly noticeable with larger diameters of the light-active core, i.e., for diameters ≥ 3 mm.

[0007] If a gooseneck liquid light guide is constructed according to the same pattern as for the fiber optic bundles described above and the light entrance end is fixed to a light source with a powerful UV lamp, manipulation of the light guide will result in deformation of the FC tube inside the holding tube, resulting in a loss of transmission and local heating of the liquid light guide. After a certain period of exposure to intense light with a radiant power of several watts, permanent damage and deformation of the fluorocarbon light guide sheath tube will occur, and the transmission of the liquid light guide will decrease rapidly.

[0008] The object of the invention is to overcome the above-mentioned disadvantages and to provide a gooseneck liquid light guide which can be coupled to high-performance light sources, such as tungsten / halogen lamps, mercury or xenon plasma lamps, or arrays of light-emitting semiconductor diodes (LEDs), and which does not show any significant transmission losses even in the long term, despite any manipulation.

[0009] The object is achieved by the lighting device defined in the appended claim 1. The subclaims relate to preferred embodiments.

[0010] According to one embodiment, the liquid light guide core, consisting of the liquid-filled fluorocarbon tube with sealing elements on both sides, is inserted into a holding tube and mounted at least at one end in the holding tube such that the light guide core, including the sealing elements, remains rotatable inside the outer holding tube but is fixed in translation along the axis of the holding tube. The other end of the light guide can also be mounted in the same way. If only one end of the liquid light guide core is mounted rotatably, it is preferably the end intended for light coupling.According to a particularly preferred embodiment, only the light entry end of the liquid light guide is rotatably mounted in the manner described, while the light exit end of the core is not subject to any restrictions with regard to rotation and translation and is merely guided coaxially in the holding tube.

[0011] Particularly preferred embodiments of the present invention are explained in more detail below with reference to the drawings, in which: Fig. 1 is a perspective view of a lighting device according to an embodiment of the present invention; Fig. 2 a sectional view of the light entrance and exit ends of the liquid light guide; Fig. 3a is a partially sectioned side view of the attachment of the liquid light guide to the housing of the light source in a first position; and Fig. 3b is a partially sectioned side view of the attachment of the liquid light guide to the light source housing in a second position.

[0012] Fig. 1 shows an overview diagram consisting of a radiation source 11 with a coupled gooseneck light guide 10. The light guide 10 comprises a position-holding tube 22, inside which the liquid-filled light guide is installed. The radiation source 11 contains a lamp with a focusing unit (not shown), consisting of a reflector and / or condenser. The lamp can be, for example, a tungsten / halogen lamp, a mercury vapor or xenon gas discharge lamp, or an LED array. The filament, the luminous plasma, or the LEDs of the array are projected onto the light entry surface of the liquid light guide 10 in a known manner by focusing means. Round flanges 13, 23 are firmly attached to both sides of the gooseneck holding tube 22, preferably by gluing. A sealing sleeve 14 can be seen at the light exit end of the liquid light guide 10.

[0013] Fig. Figure 2 shows a cross-sectional view of both end regions of a gooseneck liquid light guide 10 according to the invention. The aforementioned sealing sleeve 14 at the light exit end surrounds a glass plug 17 and the light-conducting, liquid-filled fluorocarbon tube 28, sealing it against liquid leakage using an O-ring compression seal 16. A sealing sleeve 24 is also symmetrically attached to the light entry end, which in turn firmly connects the liquid-filled tube 28 and a glass plug 27 using an O-ring compression seal 26. The sealing sleeves 14, 24 and the inner tube 28 thus form a solid unit.

[0014] The sealing sleeves 14, 24 and the outer flanges 13, 23 of the holding tube 22 are each rotatably connected to one another by a snap ring 15, 25 in that the snap ring 15, 25 simultaneously fills an outer groove of the associated sleeve 14, 24 and a coaxially extending inner groove of the associated flange 13, 23. If the holding tube 22 is in the stretched state, ie aligned straight and without curvature, the core of the liquid light guide 10 comprising the tube 28, glass stoppers 17, 27 and sleeves 14, 24 is freely rotatable and yet secured against axial translation.

[0015] In the most preferred embodiment, the snap ring 15 at the light exit end is omitted, and the tube 28 is simply guided coaxially in the retaining tube 22, so that it is not subject to any restrictions regarding rotation and translation. The connection between the light guide tube 28 and the retaining tube 22 is then established solely by the snap ring 25. This embodiment is particularly simple in design and yet fulfills the purpose of securing the light guide tube 28 in the retaining tube 22 against axial translation and allowing intrinsic rotation.

[0016] In practice, when assembling the gooseneck liquid light guide 10, care is taken to ensure that the outer diameter of the tube 28 is at least 15-30% smaller than the inner diameter of the holding tube 22. This provides the sensitive liquid light guide core with additional escape routes when manipulating the gooseneck light guide 10 during use.

[0017] Additional relief of the liquid light guide core during manipulation, particularly of the non-twistable fluorocarbon tube 28 contained therein, can be achieved if the holding tube 22 is not rigidly connected to the housing of the radiation source 11, but is mounted coaxially to the optical axis of the radiation source. However, this rotation of the holding tube 22 relative to the radiation source 11 must not be easy, because otherwise the gooseneck liquid light guide 10 cannot maintain its spatial position and will sink due to its weight and the corresponding leverage. The rotation of the holding tube 22 relative to the radiation source 11 must therefore be provided with a defined resistance, which can be achieved, for example, by a slip clutch.

[0018] Such a slip clutch is exemplified in the Fig. 3a and Fig. 3b. Here, it is realized with a magnetic ring 34, which, through its adhesive force on the housing wall 31, creates a frictional resistance against rotation. The magnetic ring 34 is preferably a permanent magnet, which is mounted in the flange 23 at the light-entrance end of the gooseneck light guide 10. The magnet is mounted coaxially to the optical axis and lies opposite a plate-ring-shaped counterpart 35 made of magnetic material, which is attached to the housing wall 31. As soon as the gooseneck light guide 10 is completely engaged in the radiation source 11 ( Fig. 3b), the magnetic ring 34 adheres magnetically to the counterpart 35. The surface friction between the flange 23 and the counterpart 35 then provides the desired defined resistance against twisting of the retaining tube 22 relative to the housing wall 31, which is not fully engaged ( Fig. 3a) does not occur.

[0019] The plate-shaped counterpart 35 can be made of magnetic stainless steel, for example, and additionally roughened to impede rotation of the light guide. Other mechanisms for a slip clutch using corrugated washers or O-rings are also conceivable.

[0020] In endurance tests, the gooseneck liquid light guide 10 according to the invention shows satisfactory stability of the optical transmissions, even after frequent manipulation and after exposure to light radiation powers of several watts.

Claims

[1] Lighting device with a radiation source (11) and a liquid light guide (10) coupled thereto, which has a liquid-filled light guide tube (28), characterized by , that the liquid light guide (10) further comprises a position-holding tube (22) made of a flexible metal which holds the bending position and within which the light guide tube (28) is arranged, the optical fiber tube (28) is firmly connected at at least one end to a sealing end piece (14; 24), the position-holding hose (22) is fixedly connected at at least one end to a tubular element (13; 23) in which the end piece (14; 24) is rotatably mounted, and the at least one end of the optical fiber tube (28) is rotatably mounted relative to the position-holding tube (22) by a connecting element (15; 25) which rotatably connects the end piece (14; 24) at the at least one end of the optical fiber tube (28) to the tube element (13; 23) on the position-holding tube (22). [2] Lighting device according to claim 1, wherein the tubular element (13; 23) is a coaxially arranged flange. [3] Lighting device according to claim 1 or 2, wherein the sealing end piece (14; 24) consists of a tubular sleeve within which at least one end of the light guide tube (28) is fastened by means of a sealing element (16; 26), preferably an O-ring. [4] Lighting device according to claim 3, wherein the sealing element (16; 26) together with a plug (17; 27) also arranged in the end piece (14; 24) at the front end of the light guide tube (28) seals the liquid light guide (10) against liquid leakage. [5] Lighting device according to one of the preceding claims, wherein the connecting element (15; 25) is a snap ring. [6] Lighting device according to claim 5, wherein the connecting element (15; 25) engages simultaneously in an outer groove of the end piece (14; 24) and a coaxially extending inner groove of the tubular element (13; 23). [7] Lighting device according to one of the preceding claims, wherein the optical fiber tube (28) is a fluorocarbon polymer, preferably Teflon FEP ® , contains and / or the position-holding hose (22) is made of a wound metallic profile strip with sealing thread or sealing wire. [8] Lighting device according to one of the preceding claims, wherein the light guide tube (28) is rotatably mounted relative to the position-holding tube (22) only at one end, preferably the light entry end, and is guided coaxially in the position-holding tube (22) at its other end without special mounting, without being subject to restrictions with regard to its rotatability and translation relative thereto. [9] Lighting device according to one of the preceding claims, wherein at the point at which the liquid light guide (10) emerges from a housing of the radiation source (11), a slip clutch is provided, which causes a defined frictional resistance against twisting of the position-holding tube (22) relative to the housing wall (31). [10] Lighting device according to claim 9, wherein the slip clutch has a magnetic ring (34) fastened to the light entry end of the position-holding tube (22), which ring provides resistance to twisting by its magnetic attraction force on a counterpart (35) fastened to the housing wall (31).

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