Optical observation device and method for equipping an optical observation device with a laser protection filter

Abstract

Optical observation device (2, 2', 2'') for use in the treatment of a treatment area (3) by means of laser radiation (47), comprising: - at least two beam paths (9A, 9B, H, M) and a number of optical elements (5, 11, 15, 29, 51, 52), wherein at least one of the optical elements (5, 51, 52) is passed by all beam paths (9A, 9B), and - at least one optical element (5, 51, 52) of the optical observation device (2, 2', 2'') is provided with at least one coating (6, 6-1, 6-2) which realizes a transmission characteristic suitable for blocking the laser radiation (47) used in the treatment, wherein at least one optical element (5, 51, 52) provided with the coating is one that is passed through by all beam paths (9A, 9B), characterized by the fact that the at least two beam paths comprise at least one main observer beam path (H) and one co-observer beam path (M) and the optical element (51, 52) with the at least one coating (6-1, 6-2) is located in a region of the optical observation device (2'') in which it is passed by both the main observer beam path (H) and the at least one co-observer beam path (M).

Description

[0001] The present invention relates to an optical observation device for use in the treatment of a treatment area using laser radiation. The invention also relates to a method for equipping an optical observation device with a laser protection filter.

[0002] Lasers have become indispensable in medical treatment. For example, in ophthalmic surgery, lasers are used to treat both the anterior and posterior segments of the eye. In the treatment of the anterior segment, for instance, a condition known as posterior capsule opacification (PCO) is addressed. PCO is a postoperative clouding of the retina following the implantation of an intraocular lens. This clouding can be removed using 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. At the distal end of the beam splitter, a laser protection filter is provided 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 optical observation device for use in the treatment of a treatment area with laser radiation, which includes a laser safety filter that does not require any additional pivoting mechanism and requires as few elements as possible. A second object of the present invention is to provide a method by which an optical observation device for use in the treatment of a treatment area with laser radiation can be equipped with a laser safety filter without requiring an additional pivoting mechanism, wherein the laser safety filter requires as few elements as possible.

[0005] The first problem is solved according to claim 1 by an optical observation device for use in the treatment of a treatment area by means of laser radiation, the second problem according to claim 5 by a method for providing an optical observation device with a laser protection filter. The dependent claims contain advantageous embodiments of the invention.

[0006] According to a first aspect of the invention, an optical observation device is provided for use in the treatment of a treatment area with laser radiation. The optical observation device comprises at least two beam paths and a number of optical elements, wherein at least one of the optical elements is traversed by all beam paths. At least one optical element of the optical observation device is provided with at least one coating which realizes a transmission characteristic suitable for blocking the laser radiation used in the treatment. According to the invention, the at least one optical element provided with the coating is one that is traversed by all beam paths. The beam paths can, for example, comprise stereoscopic partial beam paths. Additionally or alternatively, they can also include main and co-observer beam paths, documentation beam paths, etc.include, which in turn may include stereoscopic partial beam paths.

[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 paths lead 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] Because the laser protection filter is formed by at least one coating applied to at least one optical element of the optical observation device, it is not necessary to insert an additional laser protection filter—that is, an additional element with a transmission characteristic suitable for blocking the laser radiation—into the beam paths. In this way, compared to the prior art mentioned above, an additional pivoting mechanism can be avoided. Furthermore, no additional optical element for filtering out the laser radiation needs to be integrated into the optical observation device.Furthermore, because the at least one optical element provided with the coating in the optical observation system of the present invention is passed by all beam paths, it is not necessary to have a separate optical element functioning as a laser protection filter for each beam path, which is particularly advantageous in optical observation devices with a large number of beam paths.

[0012] 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 band only 20 nm wide, particularly 10 nm, centered around the center wavelength of the laser radiation, which might be 532 nm, for example, can be 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 representation achieved with the optical observation device. Color distortions are therefore so minimal that the coating forming the laser protection filter does not impair the other uses of the optical observation device.

[0013] 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.

[0014] The at least two beam paths comprise at least one main observer beam path and one secondary observer beam path. The optical element with the at least one coating is located in a region of the optical observation device where it is traversed by both the main observer beam path and the at least one secondary observer beam path. In this way, only a single optical element with at least one coating, exhibiting a transmission characteristic suitable for blocking the laser radiation, is required to implement the laser protection filter.

[0015] It offers particular advantages if the optical observation device has a main objective lens that is designed as the optical element with at least one coating. Firstly, the main objective lens can be replaced relatively easily by the user, making it very easy to retrofit existing optical observation devices. Secondly, the main objective lens is the optical element that is typically always passed through by all beam paths, especially by the main observer beam path as well as any secondary observer beam paths.

[0016] Since a primary lens typically comprises several optically effective surfaces, in particular at least two, it is advantageous if the at least one coating is applied to the optical surface where the incident light rays from the beam paths exhibit the smallest average angle of incidence. 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. The average angle can be, for example, the arithmetic mean of the angles between the light rays from the beam paths 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.

[0017] Primary lenses are typically designed as achromatic or apochromatic lenses to minimize chromatic aberration. Achromatic or apochromatic lenses are composed of two or three lenses, at least two of which form a so-called cemented element. The cemented surface, i.e., the surface where the two lenses are cemented together, is the surface where the incident light rays from the optical paths exhibit the smallest average angle of incidence. Therefore, if at least one of the optically active surfaces of the primary lens is a cemented surface, it is advantageous for at least one coating to be present on the cemented surface.

[0018] According to a second aspect of the present invention, a method is provided for equipping an optical observation device with a laser protection filter having a transmission characteristic suitable for blocking the laser radiation used in the treatment of a treatment area. The optical observation device comprises at least two partial beam paths and a number of optical elements. In the method, at least one optical element, which is traversed by all beam paths, is provided with a coating that achieves the transmission characteristic, so that the optical element with the at least one coating functions as a laser protection filter. The beam paths can, for example, comprise stereoscopic partial beam paths. Additionally or alternatively, they can also include main and co-observer beam paths, documentation beam paths, etc.include, which in turn may include stereoscopic partial beam paths.

[0019] Forming the laser protection filter by coating at least one optical element of the optical observation device makes it possible to implement the laser protection filter without having to equip the optical observation device with an additional element. Furthermore, because the coating is applied to an optical element that is traversed by all beam paths of the optical observation device, it is not necessary to coat a separate optical element for each beam path, which is particularly advantageous for optical observation devices with a large number of beam paths. In addition, compared to the prior art mentioned above, an additional pivoting mechanism can also be avoided.

[0020] The at least two partial beam paths comprise at least one main observer beam path and one secondary observer beam path. An optical element of the optical observation device is provided with at least one coating, and this element is located in a region of the optical observation device where it is traversed by both the main observer beam path and the at least one secondary observer beam path. To equip the optical observation device with the laser protection filter, only a single optical element with at least one coating is required, which has a transmission characteristic suitable for blocking the laser radiation.

[0021] In particular, an optical element of the main objective of the optical observation device can be provided with at least one coating, since, firstly, the main objective can be replaced relatively easily by the user, so that existing optical observation devices can be retrofitted very easily, and secondly, the main objective is often the optical element that is always passed by all partial beam paths and, in the case of co-observer beam paths, usually also by the co-observer beam paths.

[0022] A main objective typically comprises several optically effective surfaces. Within the scope of the invention, it is advantageous to provide the optical surface of the main objective with at least one coating where the incident light rays from the beam paths have the smallest average angle of incidence, since, particularly when an interference layer system is applied, the effectiveness of the laser protection filter deteriorates with increasing angle of incidence.

[0023] The optically effective surfaces of the main objective lens can also include a cemented surface, as is the case, for example, with achromatic or apochromatic main objectives. In this case, the cemented surface can be provided with at least one coating. The cemented surface is generally the surface where the incident light rays from the optical paths have the smallest average angle of incidence, and is therefore particularly suitable for applying the at least one coating. Fig. Figure 1 shows an operating microscope as a first example of an optical observation device for use in the treatment of a treatment area using laser radiation. Fig. Figure 2 shows a first example of a transmission characteristic of a coating. Fig. Figure 3 shows a second example of a transmission characteristic of a coating system consisting of at least two coatings. Fig. Figure 4 shows an alternative operating microscope as a second example of an optical observation device for use in the treatment of a treatment area using laser radiation. Fig. Figure 5 shows an alternative main objective of an operating microscope. Fig. Figure 6 shows another alternative operating microscope as a third example of an optical observation device for use in the treatment of a treatment area using laser radiation.

[0024] The following refers to Fig. 1 an operating microscope 2 as an exemplary embodiment of an optical observation device according to the invention. The in Fig. The surgical microscope 2 shown in Figure 1 comprises as essential components a lens 5 facing an object field 3, which can be designed, in particular, as an achromatic or apochromatic lens. In the present exemplary embodiment, the lens 5 consists of two cemented partial lenses 5-1 and 5-2, which together form an achromatic lens 5 and have three optically effective surfaces: the entrance surface facing the object plane 3, the exit surface modified from the object plane 3, and the cemented surface, i.e., the surface where lens 5-1 contacts lens 5-2. In the present exemplary embodiment, a coating 6 is present on the cemented surface, which causes the main lens 5 to simultaneously function as a laser protection filter, as will be explained later.

[0025] 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.

[0026] 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.

[0027] 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).

[0028] 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.

[0029] 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.

[0030] 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.

[0031] It should be noted that the in Fig. The illumination beam path shown in Figure 1 is highly schematic and does not necessarily represent the actual path of the illumination beam. In principle, the illumination beam path can be designed as so-called oblique illumination, which corresponds to the schematic representation in Figure 1. 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.

[0032] The in Fig. The operating microscope 2, shown as an exemplary embodiment of an optical observation device, is adapted for use in the treatment of a treatment area by means of laser radiation 247 from a laser 48. The treatment area is in Fig. 1 is represented by object field 3. As indicated by the arrows in Fig. As indicated in Figure 1, laser radiation is reflected and scattered by the object field 3 and can thus enter the stereoscopic partial beam paths 9A, 9B of the operating microscope 2. This poses a danger to the eyes of the treating physician looking through the operating microscope 2. The operating microscope 2 is therefore equipped with a laser safety filter.

[0033] The laser safety filter is in the Fig. In the exemplary embodiment shown in Figure 1, this coating 6 is implemented in the area of ​​the cemented surface between the first lens 5-1 and the second lens 5-2 of the main objective 5. This coating provides a transmission characteristic that is confined to a narrow spectral range around the center-of-mass wavelength λ. L The laser radiation 47 exhibits a very low transmission T close to 0, whereas in all other spectral ranges it exhibits a high transmission T close to 1, as shown schematically in Fig. Figure 2 shows that the coating thus acts as a blocking filter, which blocks the narrow spectral range around the center-of-mass wavelength λ. L the laser radiation 47 blocks. The width of the blocking region B of the coating 6 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 forms the center of the blocking region B. In the present exemplary embodiment, the center wavelength λ lies at this point. L of the laser radiation at 532 nm. A transmission characteristic, as shown in Figure 2, 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 47.

[0034] A transmission characteristic, as schematically shown in Fig. As shown in Figure 2, this can also be achieved through the interaction of two coatings. This variant is shown schematically in Figure 2. Fig. Figure 3 shows that, in combination, the first coating exhibits high transmission close to 1 at wavelengths below a first cutoff wavelength λ. G1 and a very low transmission close to 0 above this first cutoff wavelength λ G1A second coating exhibits very low transmission close to 0 for wavelengths below a second cutoff wavelength λ. G2 and a very high transmission close to 1 for wavelengths above the second cutoff wavelength λ G2 Both coatings thus act as edge filters. If the first cutoff wavelength λ G1 is lower than the second cutoff wavelength λ G2 is, arises between the first cutoff wavelength λ G1 and the second cutoff wavelength λ G2 a blocking region B, the width of which is the difference between the cutoff wavelength λ G2 and λ G1 This corresponds to the following. In this way, the two coatings together result in a transmission characteristic with a narrow stopband B.

[0035] The coating 6 described above can protect the eyes of the treating physician from damage caused by reflected or scattered laser radiation. Furthermore, the coating 6 can also prevent the image captured by camera 21 from being overexposed by reflected or scattered laser radiation.

[0036] The following refers to Fig. 4. A digital operating microscope 2' is described as a further exemplary embodiment of an optical observation device according to the invention. 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 merely an option in the digital operating microscope 2' and therefore does not necessarily have to be present, 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 surgical 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. Four 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. 4. As shown in Figure 4, 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.

[0037] In the Fig. In the digital operating microscope shown in Figure 4, the coating 6 serves to prevent the image taken with the camera 21 from being overexposed by reflected or scattered laser radiation.

[0038] In the Fig. 1 and Fig. In the surgical microscopes 2, 2' shown in Figure 4, the objective 5 consists solely of an achromatic or apochromatic lens. However, an objective lens system consisting of several lenses can also be used, in particular a so-called varifocal objective, with which the working distance of the surgical microscope 2, 2', i.e., the distance of the object-side focal plane, in which the field of view 3 is located, from the vertex of the first object-side lens surface of the objective, also called the focal length, can be varied. With a varifocal objective, the field of view 3, arranged in the focal plane, is also imaged to infinity, so that a parallel beam of light is present on the observer side.

[0039] An example of a varifocal lens is shown schematically in Fig. Figure 5 shows the Vario lens 50 comprising a positive element 51, i.e., an optical element with positive refractive power, which is in Fig. 5 is schematically represented as a convex lens. Furthermore, the Vario lens 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 depicted varifocal lens 50, the negative element 52 is fixed, whereas the positive element 51, as indicated by the double arrow 53, is displaceable along the optical axis OA. When the positive element 51 is in the Fig. When the position shown in 5 is moved, the cutting distance increases, so that the working distance of the operating microscope 2 from the object field 3 increases.

[0040] Although in 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 varifocal objective 50. A fixed negative element 52 therefore offers the advantage that the interior of the operating microscope 2 can be more easily sealed against external influences. Furthermore, it should be noted that, although the positive element 51 and the negative element 52 are in Fig. 5 are shown only as individual lenses, each of these elements can also be realized as a lens group or cemented element instead of as a single lens, e.g. to make the varifocal lens achromatic or apochromatic.

[0041] In the present exemplary embodiment, the varifocal lens 50 has four optically effective surfaces, namely the surfaces of the positive element 51 and the negative element 53 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 surfaces of the lenses 51 and 52 facing the object field 3 each have a coating 6-1, 6-2. These coatings 6-1, 6-2 each function as edge filters, with the first coating 6-1 having a first cutoff wavelength λ. G1 and the second coating 6-2 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 3 shows that together the coatings 6-1 and 6-2 result in a transmission characteristic with a narrow wavelength λ around the center-of-mass wavelength. Lof the laser radiation 47 centered blocking region B. It is irrelevant which of the two coatings 6-1, 6-2 is the coating with the first cutoff wavelength λ. G1 and which coating with the second cutoff wavelength λ G2 is.

[0042] Fig. Figure 6 shows, as a further exemplary embodiment of an optical observation device according to the invention, an operating microscope 2'', which has as beam paths a main observer beam path H and a secondary observer beam path M. In the present exemplary embodiment, both the main observer beam path H and the secondary observer beam path M each have stereoscopic partial beam paths which are in Fig. However, 6 cannot be seen in detail due to the selected view. The in Fig. The operating microscope 2'' shown in Figure 6 therefore comprises at least four beam paths. If it also includes a (not shown) monoscopic or stereoscopic documentation beam path, the operating microscope of the present exemplary embodiment can also have more than four beam paths. Both the main observer beam path H and the secondary observer beam path M each have a binocular tube 27-H, 27-M.

[0043] The co-observer beam path M is coupled out by means of a beam splitter 70, which is connected downstream of the main objective 5 in the beam path. In the present exemplary embodiment, this beam splitter 70 is a large beam splitter, i.e., a beam splitter that extends over both stereoscopic partial beams of the main observer beam path H and couples the two stereoscopic partial beams of the co-observer beam path M out of the stereoscopic partial beams of the main observer beam path H. Alternatively, it is possible to arrange the observation pupils of the stereoscopic partial beams of the co-observer beam path M rotated by 90° relative to the observation pupils of the stereoscopic partial beams of the main observer beam path H.

[0044] In this case, small beam splitters can be used, which can be positioned outside the stereoscopic partial beam paths of the main observer beam path H. This avoids light loss in the main observer beam path H due to the decoupling of the co-observer beam path M. If a monoscopic documentation beam path is to be decoupled, it can be extracted from one of the stereoscopic partial beam paths of either the main observer beam path H or the co-observer beam path M. It is also possible to extract it between the stereoscopic partial beam paths. If stereoscopic documentation is to be performed, corresponding stereoscopic partial beam paths are extracted from the stereoscopic partial beam paths of either the main observer beam path H or the co-observer beam path M.

[0045] The main lens 5 of the in Fig. The operating microscope shown in Figure 6 is designed as described with reference to Fig. 1 has been described. Because the coating 6 is applied to an optically effective surface of the main objective 5, the coating acts as a laser protection filter for both the main observer beam path H and the secondary observer beam path M. Instead of the one described in Fig. In the operating microscope, a variable-angle lens can also be used, as shown in the example of the objective 5 shown in 6. Fig. As explained in section 5. Since the coating 6 is also located on the main objective lens in this case, this coating also acts as a laser protection filter for both the main observer beam path H and the secondary observer beam path M.

[0046] The in Fig. The 6 binocular tubes shown, 27-H, 27-M, can either be purely optical binocular tubes, as described in relation to Fig. 1 have been described, or digital binocular tubes, as described in relation to Fig. 4 have been described. Furthermore, one of the binocular tubes 27-H, 27-M can be purely optical and the other digital. In particular, in the case of a purely optical binocular tube 27-H, 27-M, the beam path leading to this binocular tube 27-H, 27-M can also include an interface for coupling out a portion of the beam path towards one or more image sensors. It is also possible that, in addition to the main observer beam path H and the co-observer beam path M, at least one further beam path is present, such as a documentation beam path or another co-observer beam path. The documentation beam path, in particular, can also be configured as a monoscopic beam path.

[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, within the scope of the present invention as claimed in the appended claims, deviations from these exemplary embodiments are possible. For example, the coating of the varifocal lens can be designed as a single coating, as described with reference to Fig. 2 has been described. Furthermore, it is possible to apply the coating in the area of ​​a cemented surface if the varifocal lens has at least one cemented element. Likewise, the lens can be fitted with the coating in the Fig. 1 and Fig. In the 4 operating microscopes 2, 2' shown, instead of a single coating, there may also be two coatings in each case, which only together form the barrier zone B, as is the case with reference to Fig.3 has been described. The present invention is therefore not to be limited by the exemplary embodiments, but only by the attached claims. Reference symbol list 2, 2', 2" operating microscope 3. Operational field 5 lens 5-1 lens 5-2 lens 6 coating 6-1 coating 6-2 coating 7A,B divergent beams 9 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 27-H Binocular Tube 27-M Binocular Tube 29A,B Tube objective 31A,B Intermediate image plane 33A, B Prism 35A,B Eyepiece lens 37 Display 39 Optics 41 White light source 43 Deflection mirrors 45 Lighting optics 47 Laser radiation 48 lasers 49A, B Focusing lens 50 Vario lens 51 positive term 52 negative term 53 Displacement path 61A,B image sensor 63A,B Display 65A,B Eyepiece lens 67A,B cable 70 beam splitters B Restricted area H Main observer beam path M Co-observer beam path OA optical axis T Transmission

Claims

[1] Optical observation device (2, 2', 2'') for use in the treatment of a treatment area (3) by means of laser radiation (47), comprising: - at least two beam paths (9A, 9B, H, M) and a number of optical elements (5, 11, 15, 29, 51, 52), wherein at least one of the optical elements (5, 51, 52) is passed by all beam paths (9A, 9B), and - at least one optical element (5, 51, 52) of the optical observation device (2, 2', 2'') is provided with at least one coating (6, 6-1, 6-2) which realizes a transmission characteristic suitable for blocking the laser radiation (47) used in the treatment, wherein at least one optical element (5, 51, 52) provided with the coating is one that is passed through by all beam paths (9A, 9B), characterized by , that the at least two beam paths comprise at least one main observer beam path (H) and one co-observer beam path (M) and the optical element (51, 52) with the at least one coating (6-1, 6-2) is located in a region of the optical observation device (2'') in which it is passed by both the main observer beam path (H) and the at least one co-observer beam path (M). [2] Optical observation device according to claim 1, characterized by , that it has a main objective (5, 50) which comprises the optical element (5, 51, 52) with at least one coating (6). [3] Optical observation device (2, 2'') according to claim 2, characterized by , that the main objective (5) comprises several optically effective surfaces and that at least one coating (6) is present on the optical surface where incident light rays have, on average, the smallest angle of incidence. [4] Optical observation device (2, 2'') according to claim 3, characterized by , that at least one of the optically effective surfaces of the main lens (5) is a cemented surface and that at least one coating (6) is present on the cemented surface. [5] Method for providing an optical observation device with a laser protection filter (6) having a transmission characteristic suitable for blocking the laser radiation used in the treatment of a treatment area (3) by means of laser radiation (47), wherein the optical observation device (2, 2', 2'') comprises at least two beam paths (9A, 9B, H, M) and a number of optical elements (5, 11, 15, 29, 51, 52), wherein at least one optical element (5, 51, 52), which is passed through by all beam paths (9A, 9B), is provided with a coating (6) which realizes the transmission characteristic, so that the optical element (5, 51, 52) with the at least one coating (6) functions as a laser protection filter, characterized by , that the at least two beam paths comprise at least one main observer beam path (H) and one co-observer beam path (M) and the optical element (51, 52) which is provided with the at least one coating (6-1, 6-2) is located in a region of the optical observation device (2'') in which it is passed by both the main observer beam path (H) and the at least one co-observer beam path (M). [6] Method according to claim 4 or claim 5, characterized by, that the optical observation device (2, 2', 2'') has a main objective (5, 50), and an optical element (5, 51, 52) of the main objective (5, 50) is provided with at least one coating (6, 6-1, 6-2). [7] Method according to claim 6, characterized by , that the main objective (5) comprises several optically effective surfaces and that the optical surface is provided with at least one coating (6) at which incident light rays of the observation beam path have on average the smallest angle of incidence. [8] Method according to claim 7, characterized by , that at least one of the optically effective surfaces of the main lens (5) is a cemented surface and the cemented surface is provided with at least one coating (6).

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