WO2001073341A1

WO2001073341A1 - Light source positioning device

Info

Publication number: WO2001073341A1
Application number: PCT/GB2001/001186
Authority: WO
Inventors: Douglas Alastair Stewart; James Oscar Molloy; Christopher Nigel Langley
Original assignee: Tissuemed Limited
Priority date: 2000-03-25
Filing date: 2001-03-19
Publication date: 2001-10-04
Also published as: AU2001240882A1; GB0007215D0

Abstract

A device for positioning a light source (21) in an optical apparatus, comprises a support body (24) on which the light source (21) is fixed in a predetermined spatial relationship. The support body (24) is engageable with a mounting within the apparatus in such a manner that when the support body (24) is so engaged the light source (21) occupies a predetermined position within the apparatus. The support body (24) is held in a handling unit (25), that is engageable with the apparatus and contains means (41) for urging the support body (24) into engagement with the mounting.

Description

Title - Light Source Positioning Device

This invention relates to a device for the positioning of a light source in an optical apparatus.

In many applications it is necessary for a light source to be accurately positioned with respect to an optical system. One example is in apparatus used to generate light which is fed into an optical fibre. Apparatus of such a type is increasingly used for medical applications, eg to deliver light for surgical procedures such as laser welding and to activate tissue adhesive. For such applications, the light source is normally positioned in front of a reflector which collects light from the light source and focuses it onto the input end of an optical fibre. To achieve precise focussing of the light, and hence sufficient light intensity at the output end of the optical fibre, the positioning of the light source is generally critical. The light source may need to be positioned relative to the reflector with a precision of as little as ± 0.05mm.

Accurate positioning of the light source may be achieved during manufacture of the optical apparatus. However, this does not obviate the problem of accurate positioning entirely since the light source will generally have a finite lifetime (typically 1000-2000 hours of use). When the light source fails it must be replaced, and the replacement source must be as accurately positioned as the one which it replaces. For some applications, it may also be necessary to use one of a number of different light sources and hence it is desirable for such light sources to interchangeable in such a manner that the selected source is properly positioned.

Whatever the reason for replacing the light source, it is commonly the case that the source which is to be replaced is hot and must be allowed to cool prior to removal from the apparatus. This causes delay. Also, to effect replacement of the light source it may be necessary to a greater or lesser extent to dismantle the optical apparatus. This may be time-consuming, and may necessitate a considerable level of skill and/or special tools. There has now been devised a device for the positioning of a light source in an optical apparatus which overcomes or substantially mitigates the above- mentioned or other disadvantages of the prior art.

According to the invention, there is provided a device for positioning a light source in an optical apparatus, said device comprising a support body on which the light source is fixed in a predetermined spatial relationship thereto, the support body being engageable with a mounting within the apparatus in such a manner that when the support body is so engaged the light source occupies a predetermined position within the apparatus, and the support body being held in a handling unit, the handling unit being engageable with the apparatus and containing means for urging the support body into engagement with the mounting.

The device according to the invention is advantageous primarily in that it greatly facilitates the precise fitting of the light source into the optical apparatus. The support body is automatically urged into engagement with the mounting, such that the light source automatically occupies the desired position within the apparatus. Replacement light sources can be pre-assembled with the light source in precisely the desired position relative to the support body. The handling unit facilitates manipulation of the light source, even if it is hot. Furthermore, the device may enable the replacement or interchanging of light sources without the need substantially to dismantle the apparatus in which the light source is used, or the need for specialist tools or skill.

Engagement of the support body with the mounting is preferably by kinematic contact, most preferably three point kinematic contact. To achieve this, one of the support body and the mounting is preferably provided with three ball-ended lugs which engage in appropriately shaped recesses on the other component.

The mounting preferably takes the form of a collar or the like which is mounted around the envelope of the light source when the light source is installed in the apparatus. The means for urging the support body into engagement with the mounting is preferably a resilient means, eg a resilient compression spring, housed within the handling unit and acting between the handling unit and the support body.

Engagement of the handling unit with the apparatus is preferably by means of releasable detent means. Such detent means preferably take the form of a pair of spring-loaded jaws. Such jaws preferably are formed with, or define between them, one or more formations which co-operate with corresponding formations on the support body, so as to fix the orientation of the support body relative to the handling unit. The jaws may, for instance, define one or more openings which receive projections formed on the support body.

The handling unit, or at least the external parts thereof, are preferably formed in thermally insulating material so that they can be handled immediately after the light source has failed or has been switched off, without having to wait for a possibly protracted period while the light source cools. Suitable materials may include plastics materials, the components preferably being moulded, eg by injection moulding.

The support body is preferably formed in a material that serves to dissipate heat generated by the light source. Such a material is preferably a metal, most preferably aluminium.

The light source may have any suitable form for the optical apparatus in question, but for applications in which the invention is envisaged to have particular utility the light source may be an arc lamp.

The invention will now be described in greater detail, by way of illustration only, with reference to the accompanying drawings, in which

Figure 1 is a perspective view of the rear of an optical apparatus used with a light source positioning device according to the invention in the form of a lamp holder; Figure 2 is a cross-sectional side view of the apparatus of Figure 1 with the lamp holder in place;

Figure 3 is an exploded view of the lamp holder;

Figure 4 is a side view, partly in section, of the lamp holder;

Figure 5 is a plan view, partly in section, of the lamp holder; and

Figure 6 is a view similar to Figure 5, showing the lamp holder in place in the optical apparatus.

Referring first to Figure 1 , an optical apparatus is generally designated 1 and has a housing 2. The apparatus 1 is used to supply light from a light source to the input end of an optical fibre. One particular field of application of such apparatus is surgery, in which light emitted from the optical fibre may be used for, for instance, photodynamic therapy, tissue welding or cauterization, or to activate a tissue adhesive.

As can be seen in Figure 1 , the rear panel of the housing 2 of the apparatus 1 has a hinged access door 3 which closes a lamp compartment 4. The lamp compartment 4 contains a socket 5 within which a lamp holder according to the invention can be received, as described below. Another recess 6 (only partially visible in Figure 1) is also provided and is intended to hold a spare lamp holder.

The apparatus 1 is shown in greater detail in Figure 2, in which the lamp holder (generally designated 20) is shown in place. The apparatus 1 includes an elliptical reflector 11 with an axial opening 12 through which the lamp holder 20 projects. The reflector 11 is mounted on an annular bracket 13. The lamp holder 20 (described in greater detail below) includes an arc lamp 21 , the arc of which is required to occupy a precise position relative to the reflector 11 in order that light from the arc is focussed onto the end plate 32 of an optical fibre unit 33. Other optical components such as lenses, filters etc are included in the light path as appropriate. An optical fibre 34 extends from the optical fibre unit 33.

The projecting tip of the arc lamp 21 constitutes a cathode 22 which locates in a suitable electric connector 35 mounted on the central axis of the reflector 11.

The lamp holder 20 comprises (as illustrated most clearly in Figure 3), in addition to the arc lamp 21 , a mounting block 24 of generally cylindrical form, the lamp 21 projecting from one plane face of the mounting block 24, and an outer shell 25 comprising a pair of jaws 25a, b which are pivotally connected at a position intermediate their ends. Abutting edges of the jaws 25a, b are formed with cutouts which define upper and lower openings 26,27 in which corresponding shaped projections 28,29 on the mounting block 24 locate. The upper projection 28 is of greater depth than the lower projection 29 and carries on its upper surface a bar code or similar form of identification code. The length of the openings 26,27 is somewhat greater than that of the projections 28,29 so as to permit a limited degree of sliding movement of the mounting block 24 within the shell 25.

The mounting block 24 is manufactured in aluminium and as such constitutes a light weight but effective heat sink which dissipates heat generated by the lamp 21. The jaws 25a, b are injection moulded in plastics material and as such are thermally insulating. The arc lamp 21 is mounted very precisely during manufacture in the mounting block 24 so that accurate positioning of the mounting block 24 within the apparatus 1 automatically leads to precise positioning of the arc of the arc lamp 21 within the reflector 11.

The mounting block 24 is retained permanently within the shell 25, the upper projection 28 extending through the upper opening 26 and serving, together with the lower projection 29, to hold the mounting block 24 in a fixed orientation relative to the shell 25. A compression spring 41 (see Figure 2) is fitted within the shell 25 and acts between the mounting block 24 and internal stops formed integrally with the jaws 25a, b, thereby urging the mounting block 24 forwards. The leading face of the mounting block 24 constitutes, together with a corresponding face of a collar 36 fitted to the annular bracket 13, behind and around the axial opening 12 in the reflector 11 , a kinematic mount for the lamp holder. The collar 36 is of a machineable ceramic material which provides electrical insulation with high accuracy and thermal stability. The leading face of the block 24 carries three balls on protruding lugs 51 which engage in appropriately shaped recesses in the collar 36 when the lamp holder 20 is inserted into the socket 5 and engaged with the apparatus 1 as described below. The three balls define the kinematic mount origin and are adjusted during manufacture such that the lamp arc is correctly positioned relative to that origin. An electrical connector pin 52 also projects from the leading face of the block 24 and serves to establish electrical contact with the anode of the arc lamp 21 when the lamp holder 20 is engaged with the apparatus 1.

In addition to the compression spring 41 , the lamp holder 20 also accommodates a second compression spring 42 which is housed between the rear parts of the jaws 25a, b. The effect of the second compression spring 42 is to urge the rear parts of the jaws 25a, b apart, and hence the leading ends of the jaws 25a, b together. However, it is possible manually to squeeze the rear parts together, against the action of the second compression spring 42, and hence to open the leading ends of the jaws 25a, b.

In use, when it is desired to install a lamp holder 20 in the apparatus 1 , the lamp holder 20 is grasped by the jaws 25a, b in the vicinity of the second compression spring 42. The leading end of the lamp holder 20 is inserted into the socket 5 until the leading edges of the jaws 25a, b encounter the bracket 13. The leading ends of the jaws 25a, b are formed at their sides with internally projecting, sector- shaped detents 55 which engage with, and ride over, ramps 37 formed on the bracket 13. To facilitate this process the rear parts of the jaws 25a, b are squeezed together, against the action of the second compression spring 42, and then released so that the detents 55 engage behind the ramps 37. In this condition, the lamp holder 20 is retained firmly in place, the balls mounted on the lugs 51 having engaged in the corresponding recesses formed in the collar 36 so as precisely to position the arc lamp 21 relative to the collar 36, and hence relative to the elliptical reflector 11. At the same time, the connector pin 52 engages in a socket in the collar 13 to establish electrical contact to the anode of the arc lamp 21 , and the cathode 22 engages in the connector 35. The mounting block 24 is held firmly in engagement with the collar 13 by the action of the compression spring 41.

When the lamp holder 20 is fitted in this manner into the apparatus 1 , the bar code on the upper surface of the upper projection 28 on the mounting body 24 is aligned adjacent a bar code reader 61 mounted within the housing 2. The bar code may embody information regarding the particular type of lamp, a serial number or the like.

If it is desired to change the lamp, either because the lamp which is installed has failed or for some other reason, the end of the lamp holder 20 which projects from the socket 5 (see Figure 2) is grasped and the jaws 25a, b squeezed together as indicated by the arrows in Figure 6. This releases the detents 55 from behind the ramps 37 and allows the lamp holder 20 to be withdrawn. A replacement lamp holder 20 can then be installed.

Claims

1. A device for positioning a light source in an optical apparatus, said device comprising a support body on which the light source is fixed in a predetermined spatial relationship thereto, the support body being engageable with a mounting within the apparatus in such a manner that when the support body is so engaged the light source occupies a predetermined position within the apparatus, and the support body being held in a handling unit, the handling unit being engageable with the apparatus and containing means for urging the support body into engagement with the mounting.

2. A device as claimed in Claim 1 , wherein engagement of the support body with the mounting is by kinematic contact.

3. A device as claimed in Claim 2, wherein the kinematic contact is three- point kinematic contact and one of the support body and the mounting is provided with three ball-ended lugs which engage in appropriately-shaped recesses on the other of the support body and the mounting.

4. A device as claimed in any preceding claim, wherein the mounting takes the form of a collar or the like which is mounted around the envelope of the light source when the light source is installed in the apparatus.

5. A device as claimed in any preceding claim, wherein the means for urging the support body into engagement with the mounting is preferably a resilient means housed within the handling unit and acting between the handling unit and the support body.

6. A device as claimed in Claim 5, wherein the resilient means is a resilient compression spring.

7. A device as claimed in any preceding claim, wherein engagement of the handling unit with the apparatus is by means of releasable detent means.

8. A device as claimed in Claim 7, wherein the handling unit comprises a pair of spring-loaded jaws.

9. A device as claimed in Claim 8, wherein said spring-loaded jaws together define an opening within which a projection on said support body is received, thereby holding said support body in a fixed orientation relative to said jaws.

10. A device as claimed in Claim 9, wherein said jaws together define two openings, at diametrically spaced locations, within which two projections on said support body are received.

11. A device as claimed in any preceding claim, wherein at least the external parts of the handling unit are formed in thermally insulating material.

12. A device as claimed in any preceding claim, wherein said support body is formed in metal.

13. A device as claimed in Claim 12, wherein said metal is aluminium.

14. A device as claimed in any preceding claim, wherein the light source is an arc lamp.

15. Optical apparatus comprising a device as claimed in any preceding claim.

16. Optical apparatus as claimed in Claim 15, further comprising an optical fibre, to an input end of which light from said light source is supplied.