Ophthalmological optical observation device, method for equipping an ophthalmological optical observation device with a laser protection filter and fundus imaging system

Abstract

An ophthalmological optical observation device for use in laser eye treatment is provided. This device comprises a non-contact fundus imaging system with at least one optical element and a laser safety filter with a transmission characteristic suitable for blocking the laser radiation used in the eye treatment. At least one optical element of the non-contact fundus imaging system is provided with at least one coating that achieves the transmission characteristic and thus forms the laser safety filter.

Description

[0001] The present invention relates to an ophthalmological optical observation device for use in laser eye treatment. The invention also relates to a method for equipping an ophthalmological optical observation device with a laser safety filter. Furthermore, the invention relates to a non-contact fundus imaging system.

[0002] Lasers are indispensable in ophthalmic surgery. They are used in the treatment of both the anterior and posterior segments of the eye. In the treatment of the anterior segment, for example, a condition known as posterior capsule opacification (PCO) can be treated. PCO is a postoperative clouding of the retina following the implantation of an intraocular lens. This clouding can be removed with laser treatment. In the treatment of the posterior segment, laser radiation is used, for example, to reattach detached retinal tissue to the underlying tissue. To protect the eyes of the surgeon and, if necessary, their assistant, so-called surgical shields are used, which can be inserted into the beam path of an operating microscope, for example. One such surgical shield is described in German patent DE 44 09 506 A1.This radiation protection filter is swung between a beam splitter, which deflects the laser radiation towards the object being treated, and the two main objectives of an operating microscope. However, such filters require an additional swiveling mechanism below the main objective, which makes the operating microscope more complex and requires additional space for the swiveling mechanism.

[0003] US patent 5,528,426 A discloses an operating microscope with a beam splitter for extracting beam paths from the stereoscopic partial beam paths of a stereoscopic main observer beam path. A laser protection filter is provided at the distal end of the beam splitter for each stereoscopic partial beam path of the main observer beam path.

[0004] In contrast to the prior art, a first object of the present invention is to provide an ophthalmological optical observation device for use in laser eye treatment, which includes a laser safety filter that requires no additional pivoting mechanism and as few components as possible. A second object of the present invention is to provide a method for equipping an ophthalmological optical observation device for use in laser eye treatment with a laser safety filter without requiring an additional pivoting mechanism, and which requires as few components as possible. A third object of the invention is to provide an advantageous non-contact fundus imaging system.

[0005] The first problem is solved according to claim 1 by an ophthalmological optical observation device for use in eye treatment using laser radiation, the second problem according to claim 6 by a method for providing an ophthalmological optical observation device with a laser protection filter, and the third problem according to claim 11 by a non-contact fundus imaging system. The dependent claims contain advantageous embodiments of the invention.

[0006] According to a first aspect of the invention, an ophthalmological optical observation device is provided for use in laser eye treatment. The ophthalmological optical observation device according to the invention comprises a non-contact fundus imaging system with at least one optical element and a laser protection filter with a transmission characteristic suitable for blocking the laser radiation used in the eye treatment. According to the invention, at least one optical element of the non-contact fundus imaging system is provided with at least one coating which realizes the transmission characteristic and thus forms the laser protection filter.

[0007] An optical observation device is understood to be a device for observing a tissue area, e.g., an operating microscope, a slit lamp, etc., whose beam path leads to at least one eyepiece and / or at least one camera.

[0008] A transmission characteristic can be represented, for example, by a transmission curve, i.e., a curve depicting the transmission as a function of wavelength. The transmission characteristic of at least one coating can be realized by a colored coating, which forms a color filter, or in the form of an interference layer system, which forms an interference filter. In a color filter, the filtering effect is based on the absorption of the spectral range to be removed, whereas in an interference filter, it is based on the selective reflection of the spectral range to be removed by means of interference. Particularly narrow passbands can be achieved with interference filters.

[0009] Laser radiation is to be considered blocked within the meaning of the invention when it is reduced to such an extent that it is harmless to the eye of a user who is viewing the treatment area with the optical observation device and / or that it does not cause overexposure on an image sensor.

[0010] An optical element within the meaning of the invention is an element that acts upon a beam of rays to modify the beam. The action modifying the beam can be a focusing of the beam, a dispersal of the beam, a deflection of the beam, a change in the cross-sectional shape of the beam, a change in the optical path length of passing rays, etc. The action modifying the beam can be refractive, reflective, or diffractive.

[0011] In the ophthalmological optical observation device according to the invention, the non-contact fundus imaging system fulfills a second function in addition to its function of enabling the imaging of the fundus, namely the function of a laser protection filter. Because the laser protection filter is formed by at least one coating of at least one optical element of the non-contact fundus imaging system, it is not necessary to insert an additional laser protection filter, i.e., an additional element with a transmission characteristic suitable for blocking the laser radiation, into the beam path of the ophthalmological optical observation device.

[0012] Furthermore, the inventive design of the ophthalmological optical observation device offers the additional advantage that, during fundus treatment using laser radiation, the fundus is also viewed using the non-contact fundus imaging system. This means that the laser safety filter is automatically integrated into the beam path, thus increasing safety for the treating physician during fundus treatment with laser radiation. Moreover, no additional actuation element is required to swivel the laser safety filter into place, which enhances the user-friendliness of the ophthalmological optical observation device.

[0013] Since laser radiation is typically very narrowband, the coating can have a transmission characteristic that blocks a very narrow spectral range. A transmission characteristic with a blocking range of only 20 nm, particularly 10 nm, centered around the center wavelength of the laser radiation (e.g., 532 nm) is typically used. Because the wavelength range removed from the spectrum is very narrow at 20 nm, particularly 10 nm, blocking the laser radiation has only a very minor impact on the color rendering achieved with the optical observation device. Color distortions are so minimal that the coating forming the laser protection filter does not noticeably impair the use of the ophthalmic optical observation device outside of fundus treatment with laser radiation.

[0014] The transmission characteristic can be achieved with a single coating that blocks only a narrow transmission range. Alternatively, it is also possible to achieve the transmission characteristic with two coatings, each exhibiting a transmission edge. If one of the two coatings has high transmission in a wavelength range below a first cutoff wavelength and low transmission above the first cutoff wavelength, and the other coating has low transmission in a wavelength range below a second cutoff wavelength and high transmission above the second cutoff wavelength, and the first cutoff wavelength is below the second cutoff wavelength, then a narrowband transmission range can be achieved with the two coatings.Both coatings can be applied to the same optical element or to different optical elements of the non-contact fundus imaging system.

[0015] If the non-contact fundus imaging system includes a focusing lens system, at least one optical element can be part of the focusing lens system. The focusing lens system is generally located close to the main objective of the optical observation device, thus reliably preventing the entry of multiply scattered laser radiation into the observation beam path of the optical observation device.

[0016] An optical element of the non-contact fundus imaging system typically has at least two optically effective surfaces. In an advantageous embodiment of the ophthalmological optical observation device according to the invention, the at least one coating is located on the optical surface of the at least one optical element of the non-contact fundus imaging system where the incident light rays have the smallest average angle of incidence. This average can, for example, be the arithmetic mean of the angles between the light rays incident on the optical surface and the normal at the respective point of incidence. However, a weighted average or a quadratic average are also fundamentally suitable.In particular, if at least one coating is designed as an interference layer system, the effect of the laser protection filter deteriorates with increasing angle of incidence, so that a small angle of incidence is advantageous.

[0017] The focusing lens system can comprise at least one object-side lens and one image-side lens as optical elements. The optical element provided with at least one coating is preferably the object-side lens of the focusing lens system. This lens has an object-side lens surface on which the coating is preferably applied. In the focusing lens system, the object-side lens often includes the lens surface on which incident light rays exhibit the smallest average angle of incidence. This surface is generally the object-side lens surface of the object-side lens.

[0018] According to a second aspect of the invention, a method for equipping an ophthalmological optical observation device, which includes a non-contact fundus imaging system, with a laser protection filter having a transmission characteristic suitable for blocking the laser radiation used in eye treatment is provided. In the method, at least one optical element of the non-contact fundus imaging system is provided with at least one coating that realizes the transmission characteristic in order to form the laser protection filter.

[0019] By coating at least one optical element of the non-contact fundus imaging system, the system can perform a second function in addition to its primary function of imaging the fundus: acting as a laser protection filter. Furthermore, this eliminates the need for an additional laser protection filter—that is, an extra element that can be swung into the beam path and has a transmission characteristic suitable for blocking the laser radiation. This eliminates the need to operate a separate control to engage the laser protection filter, thus improving the user-friendliness of the ophthalmic optical observation device. For further details, please refer to the advantages described in relation to the ophthalmic optical observation device.

[0020] If the non-contact fundus imaging system includes a focusing lens system, at least one optical element of the focusing lens system can be coated. The focusing lens system is typically located close to the main objective of the optical observation device, thus reliably preventing the entry of multiply scattered laser radiation into the observation beam path of the optical observation device.

[0021] The non-contact fundus imaging system typically comprises at least one optical element, which includes several optically effective surfaces. Preferably, the optically effective surface at which the incident light rays have the smallest average angle of incidence is provided with the at least one coating. The average angle can, for example, be the arithmetic mean of the angles between the light rays incident on the optical surface and the normal at the respective point of incidence. However, a weighted mean or a quadratic mean are also possible. In particular, if the at least one coating is designed as an interference layer system, the effectiveness of the laser protection filter deteriorates with increasing angle of incidence, so a small angle of incidence is advantageous.

[0022] The focusing lens system of the non-contact fundus imaging system can comprise at least one object-side lens and one image-side lens as optical elements. In this case, it is advantageous if the object-side lens of the focusing lens system, preferably its object-side lens surface, is provided with at least one coating, since the object-side lens often contains the lens surface on which incident light rays have the smallest average angle of incidence. This surface is generally the object-side lens surface of the object-side lens.

[0023] According to a third aspect of the present invention, a non-contact fundus imaging system is provided, comprising at least one optical element and a laser safety filter with a transmission characteristic suitable for blocking the laser radiation used in laser eye treatment. At least one optical element of the non-contact fundus imaging system is provided with at least one coating which realizes the transmission characteristic and thus forms the laser safety filter.

[0024] Such a non-contact fundus imaging system can be advantageously used in an ophthalmic optical observation device intended for use in laser eye treatments. With the non-contact fundus imaging system according to the invention, the optical observation device can be fitted without an additional, swiveling laser safety filter, thus reducing the complexity of the device and improving its ease of use. Regarding the advantages and potential further developments of the non-contact fundus imaging system according to the invention, reference is made to the advantages and further developments described in relation to the ophthalmic optical observation device, from which the advantages and potential further developments of the non-contact fundus imaging system directly follow.

[0025] Further features, properties and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. Fig. Figure 1 shows a first example of an operating microscope as an example of an ophthalmological optical observation device. Fig. Figure 2 shows a second example of an operating microscope as an example of an ophthalmological optical observation device. Fig. Figure 3 shows an example of an ophthalmic optical observation device designed as an operating microscope, equipped with a non-contact fundus imaging system. Fig. Figure 4 shows a first example of a transmission characteristic of a laser safety filter. Fig. Figure 5 shows a first example of a focusing lens system as it can be used in the non-contact fundus imaging system. Fig. Figure 6 shows a second example of a focusing lens system as it can be used in the non-contact fundus imaging system. Fig. Figure 7 shows an example of a transmission characteristic of a laser safety filter consisting of at least two coatings.

[0026] The following refers to Fig. 1. An operating microscope 2 is described as an exemplary embodiment of an ophthalmological optical observation device that can be used in eye surgery. The in Fig. The surgical microscope 2 shown in Figure 1 comprises as essential components an objective 5 facing an object field 3, which can be designed in particular as an achromatic or apochromatic objective. In the present exemplary embodiment, the objective 5 consists of two cemented partial lenses, which together form an achromatic objective 5.

[0027] The object field 3 is positioned in the focal plane of the objective 5, so that it is imaged to infinity by the objective 5. In other words, a divergent beam of rays 7A, 7B emanating from the object field 3 is transformed into a parallel beam of rays 9A, 9B as it passes through the objective 5. The beams 7A, 7b and 9A, 9B define the beam paths of the operating microscope, namely stereoscopic partial beam paths.

[0028] On the observer side of the objective 5, a magnification changer 11 is arranged, which can be configured either as a zoom system for stepless changes in the magnification factor or as a so-called Galilean changer for stepwise changes in the magnification factor. In a zoom system, which, for example, consists of a lens combination with three lenses, the two object-side lenses can be moved to vary the magnification factor. In fact, the zoom system can also have more than three lenses, for example, four or more lenses, in which case the outer lenses can be fixed. In contrast, a Galilean changer has several fixed lens combinations that represent different magnification factors and can be alternately introduced into the stereoscopic partial beam paths defined by the partial beam bundles 9A and 9B.Both a zoom system and a Galilean changer convert an object-side parallel beam of light into an observer-side parallel beam of light with a different beam diameter. In the present exemplary embodiment, the magnification changer 11 is already part of the binocular beam path of the operating microscope 1; that is, it has its own lens combination for each stereoscopic partial beam path 9A, 9B of the operating microscope 1. In this exemplary embodiment, the magnification factor is set using the magnification changer 11 via a motor-driven actuator, which, together with the magnification changer 11, forms part of a magnification changer unit for setting the magnification factor.

[0029] On the observer side, an interface arrangement 13A, 13B is connected to the magnification changer 11, via which external devices can be connected to the operating microscope 2 and which, in the present exemplary embodiment, comprises beam splitter prisms 15A, 15B. In principle, however, other types of beam splitters can also be used, e.g., partially reflective mirrors. In the present exemplary embodiment, the interfaces 13A, 13B serve to couple a beam from the stereoscopic partial beam path 9B of the operating microscope 2 (beam splitter prism 15B) or to couple a beam into the stereoscopic partial beam path 9A of the operating microscope 2 (beam splitter prism 15A).

[0030] In this exemplary embodiment, the beam splitter prism 15A in the stereoscopic partial beam path 9A serves to reflect information or data for a viewer into the stereoscopic partial beam path 9A of the operating microscope 2 via a display 37, e.g., a digital mirror device (DMD) or an LCD display, and associated optics 39. In the other stereoscopic partial beam path 9B, a camera adapter 19 with an attached camera 21 is arranged at the interface 13B. The camera 21 is equipped with an electronic image sensor 23, e.g., a CCD sensor or a CMOS sensor. An electronic, and in particular a digital, image of the tissue area 3 can be captured by means of the camera 21, for example, for documentation purposes or to display an image of the object field 3 on a monitor.

[0031] A binocular tube 27 is connected to the interface 13 on the observer side. This tube has two objective lenses 29A, 29B, which focus the respective parallel beams of light 9A, 9B onto an intermediate image plane 31, thus imaging the observed object 3 onto the respective intermediate image planes 31A, 31B. The intermediate images located in the intermediate image planes 31A, 31B are then imaged to infinity by eyepiece lenses 35A, 35B, so that the observer can view the intermediate image with relaxed eyes. Furthermore, the distance between the two partial beams of light 9A, 9B is increased within the binocular tube by means of a mirror system or prisms 33A, 33B, in order to adapt it to the interpupillary distance of the observer. The mirror system or prisms 33A, 33B also erect the image.

[0032] The operating microscope 2 is also equipped with an illumination device that illuminates the object field 3 with broadband light. In this exemplary embodiment, the illumination device comprises a white light source 41, such as a halogen incandescent lamp or a gas discharge lamp. The light emitted from the white light source 41 is directed towards the object field 3 via a deflecting mirror 43 or a deflecting prism to illuminate it. The illumination device also includes an illumination optic 45, which ensures uniform illumination of the entire observed object field 3.

[0033] It should be noted that the in Fig. The illumination beam path shown in Figure 1 is highly schematic and does not necessarily reflect the actual course of the illumination beam path.

[0034] In principle, the lighting beam path can be designed as so-called oblique lighting, as shown in the schematic representation in Fig. 1 comes closest. In such oblique illumination, the beam path runs at a relatively large angle (6° or more) to the optical axis of the lens 5 and can, as in Fig. As shown in Figure 1, the illumination beam can run entirely outside the lens. Alternatively, the oblique illumination beam can also pass through an edge region of the lens 5. Another possible arrangement of the illumination beam is the so-called 0° illumination, in which the illumination beam passes through the lens 5 and is coupled into the lens between the two partial beam paths 9A and 9B, along the optical axis of the lens 5 in the direction of the object field 3. Finally, the illumination beam can also be implemented as a so-called coaxial illumination, in which a first and a second partial illumination beam path are present.The partial beam paths are coupled into the operating microscope via one or more beam splitters parallel to the optical axes of the observation partial beam paths 9A, 9B, so that the illumination runs coaxially to the two observation partial beam paths.

[0035] The following refers to Fig. 2 describes a digital operating microscope, which can be used in eye surgery, as an exemplary embodiment of an ophthalmological optical observation device. In the digital operating microscope 2', the main objective 5 with the coating 6 for filtering out the laser radiation 47, the magnification changer 11, which is only an option in the digital operating microscope 2' and therefore not essential, and the illumination system 41, 43, 45 do not differ from that described in Fig. 1. Operating microscope 2 with optical view. The difference lies in the fact that the one in Fig. The operating microscope 2' shown does not include an optical binocular tube. Instead of the tube objectives 29A, 29B, Fig. 1 includes the operating microscope 2' made of Fig. Two focusing lenses 49A, 49B are used to image the binocular observation beam paths 9A, 9B onto digital image sensors 61A, 61B. The digital image sensors 61A, 61B can be, for example, CCD or CMOS sensors. The images captured by the image sensors 61A, 61B are sent to digital displays 63A, 63B, which can be LED displays, LCD displays, or displays based on organic light-emitting diodes (OLEDs). As in the present example, eyepiece lenses 65A, 65B can be assigned to the displays 63A, 63B, which focus the images displayed on the displays 63A, 63B to infinity, allowing the viewer to observe them with relaxed eyes. The displays 63A, 63B and the eyepiece lenses 65A, 65B can be part of a digital binocular tube, but they can also be part of a head-mounted display (HMD) such as smart glasses. Although in Fig. 2. As shown in Figure 2, the images captured by the image sensors 61A, 61B can be transmitted to the displays 63A, 63B of a digital binocular tube via cables 67A, 67B. However, the images can also be transmitted wirelessly to the displays 63A, 63B, particularly when the displays 63A, 63B are part of a head-mounted display. Furthermore, the captured images can be displayed as stereoscopic images on a large monitor, which is viewed by operating room personnel using suitable 3D glasses. To distinguish the stereoscopic sub-images, they can be displayed on the monitor, for example, using different polarizations of the light emitted by the monitor. The 3D glasses then contain switchable polarizers that are switched synchronously with the display of the sub-images on the monitor.

[0036] If that in Fig. 1. Operating microscope shown 2. or the one in Fig. 2. An operating microscope 2', shown in Figure 2, is intended for use in posterior segment surgery, for example, and a non-contact fundus imaging system is employed. An operating microscope 2, 2' with a non-contact fundus imaging system 102 is shown in Figure 2. Fig. Figure 3 illustrates this. The non-contact fundus imaging system 102 is necessary because the fundus 110 of an eye 112 cannot be readily viewed with the operating microscope 2, 2'. Therefore, to view the fundus 110, the non-contact fundus imaging system 102 includes a so-called ophthalmoscopic magnifying lens 104, which generates an aerial image of the fundus 110 in an intermediate image plane 106. This aerial image is then viewed with the operating microscope 2, 2'. Since the operating microscope 2, 2' has a fixed focal length objective 5, the fundus imaging system 102 also includes a focusing lens system 50, which serves to shorten the focal distance of the operating microscope 2, 2' sufficiently so that the aerial image can be viewed in the intermediate image plane 106. The focusing lens system 50 will be described later with reference to the Fig. 6 and Fig. 7 will be described in detail.

[0037] For viewing the fundus 110 of an eye 112, the non-contact fundus imaging system 102 can be inserted into the observation beam path of the operating microscope 2, 2 by means of a sliding mechanism 116. When viewing the fundus 110 is no longer required, the non-contact fundus imaging system can be moved out of the beam path again. The insertion and removal of the non-contact fundus imaging system 102 is in Fig. 3 is symbolized by the double arrow 114.

[0038] The fundus 110 is examined, particularly when laser treatment of the fundus 110 is planned. For example, a laser beam 120 emitted by a laser 118 is deflected by a beam splitter 122 towards the fundus 110 of the eye 112. Light emanating from the eye towards the operating microscope 2, 2', however, passes through the beam splitter 122 without deflection. This means that reflected or scattered laser light can also enter the operating microscope 2, 2'. This can endanger the eyes of the treating surgeon or cause the actual image content to be overexposed by laser light in images captured with electronic image sensors.

[0039] One measure to prevent damage to the eyes of the treating surgeon or overexposure of the image content in images acquired with electronic image sensors is the insertion of a laser safety filter into the observation beam path of the operating microscope 2, 2'. Such a laser safety filter typically has a transmission characteristic with a narrow barrier band, which blocks only a narrow range around the center wavelength of the laser light 120.

[0040] A transmission characteristic for a laser safety filter is shown schematically in Fig. 4 shown. In a narrow spectral range around the center-of-mass wavelength λ LThe transmission characteristic of laser radiation 120 exhibits a very low transmission T close to 0, whereas it shows a high transmission T close to 1 in all other spectral ranges. The laser safety filter thus acts as a blocking filter, which blocks the narrow spectral range around the center-of-mass wavelength λ. L the laser radiation 120. The width of the blocking area B of the laser safety filter is typically a few nanometers, for example no more than 20 nm, preferably no more than 10 nm, where the center-of-mass wavelength λ L The laser radiation 120 forms the center of the blocking region B. In the present exemplary embodiment, the center wavelength λ is located at this point. L of the laser radiation at 532 nm. A transmission characteristic as found in Fig. As shown in Figure 4, this can be achieved with a spectral filter, which filters the narrow spectral range around the center-of-mass wavelength λ. LThe laser radiation is absorbed or reflected. However, the transmission characteristic can be achieved particularly advantageously using an interference layer system. In such an interference layer system, the filtering is not based on absorption or scattering, but on reflection generated by interference in the narrow spectral range around the center-of-mass wavelength λ. L of the laser radiation 120.

[0041] In the present exemplary embodiment, the laser safety filter is implemented by a coating in the focusing lens system 50 of the non-contact fundus imaging system 102. A first example of a focusing lens system 50 of the non-contact fundus imaging system 102 with a coating 60 functioning as a laser safety filter is shown schematically in Fig. 5 shown.

[0042] The focusing lens system 50 of the first example comprises a positive element 51, i.e., an optical element with positive refractive power, which is located in Fig. 5 is schematically represented as a convex lens. Furthermore, the focusing lens system 50 includes a negative element 52, i.e., an optical element with negative refractive power, which is in Fig. Figure 5 schematically depicts a concave lens. The negative element 52 is located between the positive element 51 and the object field 3, 3'. In the focusing lens system 50 shown, the negative element 52 is fixed, whereas the positive element 51 is displaceable along the optical axis OA, as indicated by the double arrow 53. When the positive element 51 is moved into the Fig. When 5 is moved from the position shown with a dashed line to the position shown with a solid line, the focal length of the focusing lens system 50 is reduced, so that the focus distance decreases and the object field 3, 3' can be located closer to the focusing lens system 50, making it possible to view the aerial image in the intermediate image plane 106.

[0043] In the present exemplary embodiment, the focusing lens system 50 has four optically effective surfaces, namely the surfaces of the positive element 51 and the negative element 52 facing the object field 3, and the surfaces of the positive element 51 and the negative element 52 facing away from the object field 3. In the present exemplary embodiment, the surface of the negative element 52 facing the object field 3 is provided with a coating 60 which Fig. The transmission characteristic shown in Figure 4 is present. Thus, lens 52 of the focusing lens system simultaneously forms the laser protection filter.

[0044] A second example of a focusing lens system for the non-contact fundus imaging system is in Fig. Figure 6 shows that this focusing lens system does not differ from the one shown in Figure 6, except for the design of the coating. Fig. 5 focusing lens system shown. The lenses of the focusing lens system are made of Fig. 6 and the focusing lens system itself are therefore designated with the same reference numerals as lenses 51, 52 and the focusing lens system 50. Fig. 5 is designated, and the function of the lenses 51, 52 of the focusing lens system 50 is not explained again to avoid repetition.

[0045] Unlike the focusing lens system made of Fig. 5 is at the one in Fig. In the focusing lens system shown in Figure 6, not only the object-side lens surface of lens 52, but also the object-side lens surface of lens 51 is coated. In this example, the coatings 60-1 and 60-2 together form the laser safety filter. These coatings 60-1 and 60-2 each function as edge filters, with the first coating 60-1 having a first cutoff wavelength λ. G1 and the second coating 60-2 a second cutoff wavelength λ G2 exhibits, where the cutoff wavelength λ G1 is lower than the second cutoff wavelength λ G2 is how this is in Fig. Figure 7 shows that together the coatings 60-1 and 60-2 result in a transmission characteristic with a narrow wavelength λ around the center-of-mass wavelength. L of the laser radiation 120 centered blocking region B. It is irrelevant which of the two coatings 60-1, 60-2 is the coating with the first cutoff wavelength λ.G1 and which coating with the second cutoff wavelength λ G2 is.

[0046] Although in the Fig. 5 and Fig. Since the positive element 51 is designed to be movable, it is also possible, in principle, to arrange the negative element 52 to be movable along the optical axis OA instead of the positive element 51. However, the negative element 52 often forms the end lens of the focusing lens system 50. A fixed negative element 52 therefore offers the advantage that the interior of the focusing lens system can be more easily sealed against external influences. Furthermore, it should be noted that, although the positive element 51 and the negative element 52 in Fig. 5 are shown only as individual lenses, each of these elements can be realized not only as a single lens but also as a lens group or cemented element, e.g. to make the focusing lens system achromatic or apochromatic.

[0047] The present invention has been described in detail with reference to exemplary embodiments for illustrative purposes. However, a person skilled in the art will recognize that the present invention, as claimed in the appended claims, may deviate from these exemplary embodiments. For example, the coating can be arranged in the area of ​​a cemented surface if the focusing lens system has at least one cemented element. Furthermore, the non-contact fundus imaging system can be designed to be inserted not by means of a linear movement, but by means of a pivoting movement. Additionally, the non-contact fundus imaging system can have at least two ophthalmoscopic magnifying lenses arranged in a revolver mechanism, which can be used alternatively.The present invention is therefore not to be limited by the exemplary embodiments, but only by the attached claims. Reference symbol list: 2.2' Operating microscope 3 Object field 5 lens 5-1 lens 5-2 lens 7A, B divergent beams 9A,B stereoscopic partial beam path 11 magnification changers 13A,B Interface arrangement 15A,B Beam splitter prism 19 camera adapters 21 camera 23 Image sensor 37 Display 39 Optics 41 White light source 43 Deflection mirrors 45 Lighting optics 47 Laser radiation 49A,B Focusing lens 50 focusing lens system 51 positive term 52 negative term 53 Displacement path 60 coating 60-1 coating 60-2 coating 61A,B image sensor 63A,B Display 65A,B Eyepiece lens 67A,B cable 102 Fundus imaging system 104 Ophthalmoscopic magnifying glass 106 Intermediate image plane 110 Fundus 112 Eye 114. Double arrow 116 Sliding mechanism 118 Laser 120 laser radiation 122 beam splitters B Restricted area H Main observer beam path M Co-observer beam path OA optical axis T Transmission QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 44 09 506 A1

[0002] US 5,528,426 A

[0003]

Claims

[1] Ophthalmological optical observation device (2, 2') for use in eye treatment using laser radiation (120), comprising: - a non-contact fundus imaging system (102) with at least one optical element (51, 52, 104) and - a laser protection filter (60, 60-1, 60-2) with a transmission characteristic suitable for blocking the laser radiation (120) used in eye treatment, characterized by , that at least one optical element (51, 52) of the non-contact fundus imaging system (102) is provided with at least one coating (60, 60-1, 60-2) which realizes the transmission characteristic and thus forms the laser protection filter. [2] Optical observation device (2, 2') according to claim 1, characterized by , that the non-contact fundus imaging system (102) comprises a focusing lens system (50) and the optical element (51, 52) is part of the focusing lens system (50). [3] Optical observation device (2, 2') according to claim 1 or claim 2, characterized by , that the non-contact fundus imaging system (50) has at least one optical element (51) comprising several optically effective surfaces, and that at least one coating (60) is present on the optical surface where incident light rays have the smallest angle of incidence on average. [4] Optical observation device (2, 2') according to claim 2 and claim 3, characterized by , that the focusing lens system (50) comprises at least one object-side lens (52) and one image-side lens (51) as optical elements, and that the optical element provided with at least one coating (60) is the object-side lens (52) of the focusing lens system (50). [5] Optical observation device (2, 2') according to claim 4, characterized by, that the object-side lens (52) comprises an object-side lens surface and the coating (60) is arranged on the object-side lens surface. [6] Method for equipping an ophthalmic optical observation device (2, 2') comprising a non-contact fundus imaging system (102) with a laser protection filter (60, 60-1, 60-2) having a transmission characteristic suitable for blocking the laser radiation (120) used in eye treatment (120), characterized by , that at least one optical element (51, 52, 104) of the non-contact fundus imaging system (102) is provided with at least one coating (60, 60-1, 60-2) which realizes the transmission characteristic to form the laser protection filter. [7] Method according to claim 6, characterized by, that the non-contact fundus imaging system (102) has at least one optical element (52) comprising several optically effective surfaces, and that the optically effective surface is provided with the at least one coating (60) at which incident light rays have the smallest angle of incidence on average. [8] Method according to claim 6 or claim 7, characterized by , that the non-contact fundus imaging system (102) comprises a focusing lens system (50) and the optical element (51, 52) which is provided with at least one coating (60, 60-1, 60-2) is an optical element (51, 52) of the focusing lens system (50). [9] Method according to claim 8, characterized by, that the focusing lens system (50) comprises at least one object-side lens (52) and one image-side lens (51) as optical elements (51, 52) and the object-side lens (52) of the focusing lens system (50) is provided with at least one coating (60). [10] Method according to claim 9, characterized by , that the object-side lens (52) of the focusing lens system (50) has an object-side lens surface on which the coating (60) is arranged. [11] Non-contact fundus imaging system (102) with at least one optical element (51, 52, 104) and a laser protection filter with a transmission characteristic suitable for blocking the laser radiation (120) used in eye treatment with laser radiation (120), characterized by, that at least one optical element (51, 52, 104) of the non-contact fundus imaging system is provided with at least one coating (60, 60-1, 60-2) which realizes the transmission characteristic and thus forms the laser protection filter.

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