DE10349297A1 - Adapter to be connected to eye for laser treatment of cornea, comprising contact element for precise adjustment of focus - Google Patents

Abstract

The adapter (12) is attached to the laser treatment device with a clamping element and can be used in order to facilitate the beam to act precisely on the area to be treated. A conical transparent element (12) is positioned below the lower of two lenses and on top of the retina with its narrow side (22) formed in the shape of the surface to be obtained by the treatment. Several reference points (25) are located at the bottom (22) of the element (12) directing the incoming beam to the control unit in order to create the guiding pattern for the shape to be formed.

Description

The The invention relates to an adapter for coupling a laser processing apparatus with an object to be processed, which has a deformable surface, wherein the adapter has an input side, which via a locking mechanism across from the laser processing device is fixable, an output side has, which can be applied to the deformable surface and this case a desired one Target shape is, the adapter is attachable to the object and one from the laser processing device over a certain range scanned laser beam supplied to the input side via a Beam path leads to the voltage applied to the output side surface. The invention further relates to a laser processing apparatus for one such adapter with a beam deflection device for scanning a laser beam.

at The material processing by means of laser radiation is usually a scanning used to be processed areas of the object with the laser beam. The accuracy of the positioning of the laser beam determines usually the precision achieved during processing. Will the laser beam Focused on a processing volume, it requires an exact three-dimensional positioning. Indicates the object to be edited a deformable surface on, is it for a high-precision machining usually indispensable, the surface shape to know or the deviation of the surface shape to a predetermined Target shape as possible to keep low. For Such applications is the adapter mentioned above, since he is the deformable surface of the to be processed object gives a desired target shape.

This is particularly necessary in the micromachining of materials, the only small linear optical absorption in the spectral range have the processing laser radiation. With such materials become common non-linear interactions between laser radiation and material used, usually in the form of an optical breakthrough, the focus of the laser beam is generated. Because the editing effect with it only takes place in the laser beam focus, it is essential to the focal point align exactly three-dimensionally. In addition to a two-dimensional Distraction of the laser beam is thus an exact depth position the focus position required. The aforementioned adapter facilitates This is because when applied to the object adapter known optical conditions In particular, refractive ratios are present in the beam path.

A typical application for such an adapter is the ophthalmic surgical procedure known as LASIK, in which a laser beam to a focal point of the order of magnitude of a micrometer is focused in the cornea. The focus is on then a plasma that causes a local separation of the corneal tissue. By appropriate juxtaposition of the generated in this way local separation zones macroscopic sections are realized and a specific corneal subvolume isolated. By removal the partial volume then becomes a desired refraction change the cornea reaches, so that a Defective vision correction possible is.

to execution of the method, the exact positioning of the laser beam is essential, which is why the mentioned Adapter fulfills a dual function: it not only provides the required optical properties the introduction of the laser beam into the cornea safely, but he fixes the eye also, preferably with respect to several degrees of freedom, especially preferred with respect all possible Degrees of freedom. Movements of the eye relative to the laser processing device are prevented.

One example for such an adapter is for example in WO 03/002008 A1 described. There called the "Planarisierungslinse" adapter has a suction ring attached by means of negative pressure on the eye is. In the suction ring, a glass plate is inserted by means of a clamp is pressed into the suction ring. The clamp attached at the same time a flange on the suction ring, which on the laser processing device firmly attached. The multi-part adapter of WO 03/002008 A1 squeezes the surface the cornea shallow, which achieves simple standard geometries become. However, this is for the patient very uncomfortable. In addition, a planarization the cornea surface undesirable in some surgical procedures.

Of the The invention is therefore based on the object, an adapter or a laser processing device of the type mentioned above to educate that not must necessarily be worked with a plane geometry.

This object is achieved with an adapter for coupling a laser processing apparatus to an object to be processed, which has a deformable surface, wherein the adapter has an input side, which is fixable via a shutter mechanism relative to the laser processing apparatus, an output side, which can be applied to the deformable surface and this gives a desired target shape, the ad Apter can be attached to the object, a scanned by the laser processing device over a certain range supplied at the input side laser beam via a beam path to the voltage applied to the output side surface, dissolved by the adapter in the beam path marking structures, the optically scanned by means of the scanned laser radiation over the area are detectable and encode an identifying the adapter information.

The Invention is further provided with a laser processing apparatus for a such adapter, with a beam deflection device for scanning solved by a laser beam, which has a detector device for optically detecting the marking structures by means of the laser beam and a detector device read-out control device, which the beam deflection device which determines the information characterizing the adapter and taken into account in the control of the beam deflection device.

Of the Adapter thus serves to the input side, a fixed coupling with manufacture of the laser processing apparatus. The to the laser processing device oriented input side of the adapter is therefore suitable Means for fixed connection to the object-oriented output (e.g. distal end) of the laser processing device or its optical System designed so that a based on the laser processing device fixed fixation means a closure mechanism possible is. For the locking mechanism For example, the formation of a flange on the adapter in question.

On the output side, the adapter ensures that the deformable surface of the object has a desired desired shape. For attachment of the adapter to the object suitable means are provided; in an ophthalmological application, a vacuum fastening device, such as a suction ring, as it is known from WO 03/002008 A1 or from EP 1 159 986 A2 is known to be used.

The provided in the beam path of the adapter marking structures allow the laser processing device, information about the used To get adapter. This can be, for example, a type number of the adapter, an individual name or information about the Target shape, which gives the adapter the deformable surface, act.

Around to provide this information directly to the laser processing device, the marking structures in the beam path are arranged so that they the scanned laser radiation are optically detectable. separate Information transfer mechanisms can omitted, instead, the laser processing device by means of suitable laser beam scanning detect the marking structures and extract the information characterizing the adapter.

Of the inventive adapter as well as the laser processing device according to the invention enable it, application-adapted Using adapters without running the risk of accidentally with not for to work with the current adapter matching operating parameters. A possible Error source is switched off and the overall laser processing quality is increased.

Conveniently, you will try be so few laser beam sources in the laser processing device as possible to use, as additional Laser beam sources usually associated with further costs. So you can remember the laser beam emitted by the treatment laser also equal to optically detecting the marking structures. there it has to the peak intensity and the average power can be reduced, on the one hand a Load on the object to be processed, i. on the eye of the patient To avoid, and above all, a processing effect on the adapter to prevent. It is therefore expediently in the laser processing apparatus to provide a device for Laserstrahlenergieminderung, the for the optical detection of the marking structures the energy of the Treatment laser emitted laser beam at least temporarily reduces. For this Purpose, for example, an energy reducer in the beam path switched or activated in the beam path. Alternatively, you can also the property more usual pulsed laser, between the individual laser pulses Give off background radiation with greatly reduced power. These Background radiation can for the detection of the marking structures are used, and a Energy reducer is then eliminated.

At which point in the beam path are the marking structures, is for the adapter according to the invention not decisive; It is only essential that they are by means of Scanned laser radiation emitted by the laser processing device are palpable; they are therefore within a space area, in which the laser processing device the focus of the laser beam can position.

The laser radiation used in this case can be identical to the processing laser radiation; this does not have to be the case. Conveniently, however, the laser processing device for scanning the laser radiation will use the same scanning device, which also for the Bearbeitungsla is used. The area in which the marking structures are then also represents the potential processing area.

When Marking structure is any training of the adapter suitable which makes it possible Information within the beam path retrievable deposit. Conveniently, you become spatial zones shape, at least in terms of an optical property differ from the remaining beam path of the adapter. At this optical property may be, for example, the reflection property or more generally, to the refractive index of the spatial zone. The marking structures can then similar, for example a bar code, wherein a back reflection, scattering or Absorption or dispersion of the radiation can distinguish a spatial zone.

For the the Marking structures of distinctive optical properties comes in particular a spectral range in question, the above UV absorption bands optical materials, i. above 400 nm. A possible upper limit results from the desired spatial resolution and can typically at 2 μm be specified. Preferably, for the optical property a spectral range between 0.8 μm and 1.1 μm used. Depending on the location resolution can the marking structures size dimensions between 1 μm and 100 μm, preferably between 3 μm and 10 μm to have.

To the Forwarding of the input side supplied radiation to the output side come in the adapter a variety of mechanisms in question. For eye optics Method is the adapter expediently in the manner of a contact glass train so that the Beam path at least partially for processing laser radiation transparent material, in particular glass. In a particularly advantageous embodiment the adapter has a cylindrical or frustoconical body, its one end surface as the starting page with the desired Target shape of the surface is trained. The adapter must then only be placed on the deformable surface to this the desired To give desired shape.

The Information encoded by the marking structures may be any Characteristics of the adapter mark, for example, geometric or Material properties. A particularly preferred application is to see in it the target shape passing through the exit side of the adapter is defined, to describe or to deposit information about it. For example, you can the marking structures the refractive properties of the desired shape play.

A appropriate application for the Adapter is, as already mentioned, Training as a contact lens for the eye surgery. Of course it can also be a special one equipment Act that replaces the actual contact glass or purpose a measurement before the treatment attached to the actual contact glass becomes.

The Laser processing device according to the invention for the adapter according to the invention is able by means of the detector device, the marking structures to detect optically and in the control device for the control the beam deflection device to be considered. Is the laser processing device for the LASIK method is formed, the control device can by the information identified target shape in the control so consider, that the breakthroughs to be generated also to the desired Places lie.

Of the Treatment laser is usually pulsed work. It is therefore in this regard to a training preferred in which a pulsed treatment laser for an ophthalmological Method is used, wherein the object is the cornea and the control means comprises the beam deflecting means and the Treatment laser so controls that the laser beam at predetermined locations in the eye optical breakthroughs generates, and thereby identified by the information target shape the cornea considered.

The Invention will now be described by way of example with reference to the drawings explained in more detail. In the drawing shows:

1 a schematic representation of a laser processing apparatus for an ophthalmological procedure,

2 a schematic representation of the cornea of a patient,

3 a perspective view of a contact glass for the laser processing device of 1 .

4 a sectional view of the contact glass of 3 and

5 a plan view of the contact glass of 3 ,

1 shows a treatment device for an ophthalmological procedure similar to that in the EP 1159986 A1 or the US 5549632 . described The treatment device 1 of the 1 serves to ei one eye 2 a patient to perform an ametropia correction according to the known LASIK method. For this purpose, the treatment device 1 a laser 3 on, the pulsed laser radiation emits. The pulse duration is in the femtosecond range, and the laser radiation acts by means of non-linear optical effects in the cornea in the manner described above. The one from the laser 3 along a optical axis A1 emitted treatment beam 4 falls on a beam splitter 5 that the treatment beam 4 on a scanning device 6 passes. The scanning device 6 has two scan mirrors 7 and 8th which are rotatable about mutually orthogonal axes, so that the scanning device 6 the treatment beam 4 deflects two-dimensionally. An adjustable projection optics 9 focuses the treatment beam 4 on the eye 2 , The projection optics 9 has two lenses 10 and 11 on.

The lens 11 is a contact glass 2 downstream, that via a bracket H firmly with the lens 11 and thus the beam path of the treatment device 1 connected is. The contact glass to be described later 12 lies on the cornea of the eye 2 at. The optical combination of treatment device 1 with attached contact glass 2 causes the treatment beam 4 in one in the cornea of the eye 2 located focus 13 is bundled.

The scanning device 6 will be just like the laser 3 and the projection optics 9 via (unspecified) control lines from a control unit 14 driven. The control unit 14 determines the position of the focus 13 both transverse to the optical axis A1 (through the scanning mirrors 7 and 8th ) and in the direction of the optical axis A1 (through the projection optics 9 ) in front.

The control unit 14 continue to read a detector 15 out, the radiation backscattered from the cornea, the beam splitter 5 as re-radiation 16 happens, reads. This can be done confocal imaging. On the importance of the detector 15 will be discussed later.

The contact glass 12 ensures that the cornea of the eye 2 receives a desired target shape. This is schematically in 2 shown a section through the cornea 17 shows. To get an exact positioning of the focus 13 in the cornea 17 To reach, the curvature of the cornea must 17 be taken into account. The cornea 17 has an actual shape 18 which varies from patient to patient. The contact glass 12 lies now on the cornea 17 such that it in a desired desired shape 19 deformed. The exact course of the desired shape 19 depends on the curvature of the eye 2 facing surface of the contact glass 12 from. This will be explained later on the basis of 4 become clearer. It is essential only that through the contact glass 12 known geometrical and optical conditions for the introduction and focusing of the treatment beam 4 in the cornea 17 given are. Because the cornea 17 on the contact glass 12 is applied and this in turn on the holder H relative to the beam path of the treatment device 1 is stationary, the focus may be 13 by controlling the scanning device 6 as well as the adjustable projection optics 9 three-dimensionally accurate in the cornea 17 be positioned.

3 shows a perspective view of the contact glass 12 , As can be seen, the contact glass has 12 a glass body 20 on that for the treatment beam 4 is transparent. On a top 21 of the truncated glass body 20 becomes the treatment beam 4 coupled; this top 21 is the lens 11 assigned.

At a bottom 22 of the contact glass 12 lies the cornea 17 at. Like the sectional view of the 4 shows is the bottom 22 in the desired nominal shape 19 curved so that they are in full contact with the eye 2 the desired shape of the cornea 17 causes.

Near the top 21 is on the contact glass 12 a flange surface 23 formed on the the contact glass 12 is fixed in the holder H by clamping. The flange surface 23 represents a fastening means, which is tuned to the one closure mechanism realizing holder H.

The main axis of symmetry A2 of the frusto-conical glass body 20 is by fastening over the flange surface 23 in firm connection with the treatment device 21 and adjusted to match the optical axis A1. Inside the vitreous 20 is a code structure 24 , annular in the embodiment, formed. The distance to the main optical axis A2 is chosen to be as large as possible in the exemplary embodiment, so that the code structure 24 only with almost maximally deflected treatment beam 4 in the treatment beam 4 radiated volume of the vitreous body 20 lies.

As the 4 and 3 show, lies the code structure 24 in the volume of the glass body, preferably at the edge or near the edge of the frustoconical glass body 20 , The code structure 24 consists of several reflector zones 25 that for the laser 3 emitted radiation are reflective. If the treatment beam falls 4 on a reflector zone 25 , radiation energy is backscattered, then from the detector 15 is recorded.

The reflector zone 25 can also be on the top 21 or the bottom 22 the contactgla ses 12 that is, applied on the entrance or exit surface of the adapter in the form of a suitable layer structure or suitable reflective or non-reflective layers. It is also possible to provide zones or layers with increased elastic light scattering around the reflector zones 25 to realize.

Based on the signal of the detector 15 can the controller 14 thus, realize that the treatment beam 4 on a reflector zone 25 is directed. The sequence of the annular reflector zones 25 in the code structure 4 thus provides a total of a coded signal, which in the embodiment, the curvature of the bottom 22 of the vitreous 20 and thus the geometry of the desired shape 19 reproduces the cornea 17 with the applied contact glass 12 Has.

In order to carry out this information extraction, already explained in principle, the control unit controls 14 on the one hand the laser 3 in an operating mode in which only one beam 4 is emitted with greatly reduced radiation intensity. This can be done, for example, by activating or swiveling in a suitable radiation attenuator. Is it the laser? 3 It is also possible to use a much weaker background radiation, which may be present outside the pulse mode, around a pulsed laser radiation source.

Alternatively, it is possible to couple in an additional laser, for example via a further beam splitter, that of the scanning device 3 is upstream. This laser beam may thus be either the possibly suitably attenuated treatment beam 4 or to act a separate laser beam in front of the scanning device 6 is coupled into the beam path along the optical axis A1.

To the code structure 24 to read out, controls the controller 14 the projection optics 9 as well as the scanning device 6 such that the focus of the laser radiation is passed over the area in which the code structure 24 is expected. The return reflexes are in the signal of the detector 15 detected, assigned to the current focus position and evaluated by means of suitable means, (for example, suitable processing electronics and a memory module) with regard to the coded information. The detection of the reflector zone 25 in the processing unit of 1 may preferably be confocal in order to achieve the highest possible resolution along the optical axis A1 or A2 (ie in the depth direction).

The information thus obtained via the adapter is then from the control unit 14 in the subsequent treatment of the cornea 17 considered. For example, the control of the focus 13 by means of the scanning device 6 and the projection optics 9 so causes the desired shape 19 of the currently used contact glass 12 is taken into account. Alternatively, even when scanning a disabled contact glass, the treatment device 1 be locked so that no treatment is possible. Additionally or alternatively, corresponding information about the currently used contact lens can be output by suitable means.

Claims (12)

Adapter for coupling a laser processing device ( 1 ) with an object to be processed ( 2 ), which has a deformable surface ( 17 ), wherein the adapter ( 12 ) - an input page ( 21 ), which via a closure mechanism (H) relative to the laser processing apparatus ( 1 ) is fixable, - an output side ( 22 ) to the deformable surface ( 17 ) can be applied and this thereby a desired target shape ( 19 ), where the adapter ( 12 ) on the object ( 2 ), - one of the laser processing device ( 1 ) over a certain range scanned at the input side ( 21 ) supplied laser beam ( 4 ) via a beam path to the output side ( 22 ) adjacent surface ( 17 ), characterized in that the adapter ( 12 ) in the beam path marking structures ( 25 ) which is scanned by means of the laser radiation scanned over the region ( 4 ) are optically detectable and one the adapter ( 12 ) code indicative information. Adapter according to claim 1, characterized in that the marking structures comprise spatial zones ( 25 ), which at least with regard to an optical property of the remaining beam path of the adapter ( 12 ). Adapter according to claim 2, characterized in that that the optical property is the refractive index. Adapter according to one of the above claims, characterized in that the beam path at least partially a material transparent to processing laser radiation ( 20 ), in particular glass. Adapter according to claim 4, characterized by a cylindrical or truncated conical body whose one end surface ( 22 ) as the starting side with the desired nominal shape ( 19 ) of the surface ( 17 ) is trained. Adapter according to one of the above claims, characterized by a flange ( 23 ) for the shutter mechanism (H). Adapter according to one of the above claims, characterized by a vacuum fastening device for fastening to the object ( 2 ). Adapter according to one of the preceding claims, characterized in that the information passing through the output side ( 22 ) specified target shape ( 19 ), in particular their refractive properties. Adapter according to one of the above claims, characterized characterized in that as a contact glass for the Eye surgery is formed. Laser processing apparatus for an adapter according to one of the preceding claims, comprising - a beam deflection device ( 6 . 9 ) for scanning a laser beam ( 4 ) beyond the certain range, characterized by - a detector device ( 5 . 15 ) for optically detecting the marking structures ( 25 ) by means of the laser beam ( 4 ) and - a detector device ( 5 . 15 ) read-out control device ( 14 ), which the beam deflection device ( 6 ) that drives the adapter ( 12 ) characterizing information and this in the control of the beam deflection device ( 6 . 9 ) considered. Laser processing apparatus according to claim 10, characterized by a pulsed treatment laser ( 3 ) for an ophthalmological procedure in which the object is the cornea ( 17 ), the control device ( 14 ) the beam deflection device ( 6 . 9 ) and the treatment laser ( 3 ) so that the laser beam ( 4 ) at predetermined locations ( 13 ) in the eye ( 2 ) generates optical breakthroughs, while the identified by the information target shape ( 19 ) of the surface of the cornea ( 17 ) considered. Laser processing apparatus according to claim 11, characterized by a laser beam energy reduction device which is adapted to optically detect the marking structures ( 25 ) the energy of the treatment laser ( 3 ) emitted laser beam ( 4 ) at least temporarily reduces.