an illumination device according to the invention is shown in fig1 in a greatly simplified illustration . the illumination device comprises a light - emitting diode 1 as a light source and a condenser optical system 3 , with the aid of which the illumination is optimized for the observation . the condenser optical system 3 is illustrated schematically as a lens in fig1 to 16 . however , in general it is composed of a plurality of lenses . if the illumination device is used together with a surgical microscope , the illumination beam path can , in principle , be routed past the main objective of the surgical microscope , or alternatively it can be routed through the main objective . if the illumination beam path is routed through the main objective , the main objective can be considered to be part of the condenser optical system of the illumination beam path . in this case , in addition to the optical components of the main objective , the condenser optical system comprises further optical components which are embodied such that , together with the main objective , they ensure optimum illumination of the observation object . in the following description of the exemplary embodiments of the illumination device , which is performed with reference to fig1 to 16 , the condenser optical system 3 can thus also comprise the main objective of a surgical microscope if the illumination device is used in conjunction with a surgical microscope . moreover , a light - deflecting element 5 is arranged in all exemplary embodiments ; it is used to deflect the illumination light in the direction of the observation object 7 . although the light - deflecting element 5 is arranged between the light source 1 and the condenser optical system 3 in the exemplary embodiments , the condenser optical system 3 can also be arranged between the light source 1 and the light - deflecting element 5 . moreover , the light - deflecting element 5 can be a beamsplitter , for example a partly transparent mirror , if the illumination beam path is routed through the main objective of a surgical microscope . in this case there is the option of arranging the light - deflecting element 5 in the observation beam path such that the illumination light can be coaxially superposed on the stereoscopic partial observation beam paths of the surgical microscope . in the exemplary embodiment illustrated in fig1 , there is a stop wheel 9 with at least two stops 11 , 13 , which can alternately be introduced into the illumination beam path . the stops 11 , 13 can have the same stop diameter , or else they can have different stop diameters . converter elements 15 , 17 are arranged on both stops 11 , 13 . the two converter elements 15 , 17 differ in terms of their converter phosphors . instead of being arranged directly in front of the radiant field stops 11 , 13 , as shown in fig1 , the converter elements 15 , 17 can also be arranged directly in the stop opening . the light - emitting diode 1 used in the present exemplary embodiment emits narrow - band light , part of which is converted into green light and / or yellow light and / or red light , i . e . into light with a longer wavelength , by means of the converter phosphor . the superposition of the blue initial light and the converted light then leads to a broad or white spectral wavelength distribution . a suitable selection of the phosphors thus allows wavelength distributions with different spectral widths to be realized , for example to allow illumination with different color temperatures . in the second exemplary embodiment , shown in fig2 , use is also made of a narrow - band blue light emitting light - emitting diode 1 as a luminescence emitter . however , like in all other exemplary embodiments , use can also be made of a different type of luminescence emitter , for example an organic light - emitting diode or , provided that the luminous intensity is sufficient , an electroluminescent film . the luminescence emitter likewise need not emit blue light . rather , it can also emit in a different spectral wavelength range that permits converting at least part of the light into light with a longer wavelength . in contrast to the exemplary embodiment illustrated in fig1 , there is a fixed stop 19 in the exemplary embodiment shown in fig2 , with a converter - element wheel 21 with at least two different converter elements 23 , 25 being arranged upstream of said fixed stop on the light - source side . rotating the converter - element wheel 21 thus allows different converter elements 23 , 25 to be alternately introduced into the illumination beam path in order to allow illumination with different spectral wavelength distributions . fig3 shows a third exemplary embodiment of the illumination device according to the invention , in which there is an illumination beam path with an intermediate image . a collector optical system 27 which generates an intermediate image of the light - emitting diode 1 is present in such an illumination device between the light source 1 , which once again is a narrow - band light - emitting diode , and the condenser optical system 3 . there is an aperture stop 29 at the location of the intermediate image and it allows the brightness of the illumination to be set . in the exemplary embodiment shown in fig3 , there is a converter - element wheel 31 between the light - emitting diode 1 and the collector optical system 27 , and it has at least two different converter elements 33 , 35 which can alternately be introduced into the illumination beam path . analogously to the condenser optical system 3 , the collector optical system 27 is illustrated merely as a lens for simplicity . however , in general it comprises a plurality of optical elements for increasing the imaging quality of the collector optical system 27 . it goes without saying that this also holds true for all other exemplary embodiments in which the collector optical system is merely illustrated as a single lens . a fourth exemplary embodiment of the illumination device according to the invention is illustrated in fig4 . this exemplary embodiment constitutes a combination of the exemplary embodiments from fig1 and 2 . like in the exemplary embodiment illustrated in fig1 , there is a stop wheel 37 with at least two different stops 39 , 41 that can penetrate the illumination beam path . in the present exemplary embodiment , there is at least one single stop 39 and a double stop 41 . here , the double stop 41 serves to implement a coaxial illumination beam path by coaxially superposing two partial beam paths of the illumination on the stereoscopic partial observation beam paths of a surgical microscope . however , in contrast to the exemplary embodiment illustrated in fig1 , the converter elements are not arranged directly on the stops ; rather , they are on their own converter - element wheel 43 . said wheel comprises at least two converter elements 45 , 47 , which differ from one another in terms of their converter phosphors . the converter elements 45 , 47 can alternately be introduced into the illumination beam path in order to realize illumination light with different spectral wavelength distributions . the number of converter elements 45 , 47 on the converter - element wheel 43 need not in this case correspond to the number of stops 39 , 41 on the stop wheel 37 . as a result of the separate arrangement of the stops and the converter elements on different wheels , there are particularly many combination options between stops and converter elements , and so a particularly flexible illumination device can be implemented . a fifth exemplary embodiment of the illumination device according to the invention is illustrated in fig5 . this exemplary embodiment differs from the exemplary embodiment illustrated in fig4 in that there is an led wheel 49 instead of the converter - element wheel 43 . arranged on said led wheel there are arranged at least two light - emitting diodes 51 , 53 which differ from one another in respect of the spectral wavelength distribution of the light emitted by them . the two light - emitting diodes 51 , 53 can alternately be introduced into the illumination beam path with the aid of the light - emitting diode wheel 49 . it goes without saying that the light - emitting diode wheel 49 can also have more than two light - emitting diodes . all light - emitting diodes arranged on the light - emitting diode wheel 49 preferably differ from one another in respect of the spectral wavelength distribution of the light emitted by them . since different colored light emitting light - emitting diodes are present as luminescence emitters in the exemplary embodiment illustrated in fig5 , it is possible to dispense with the use of converter elements . however , this exemplary embodiment is particularly flexible if additionally at least one converter element that can be introduced into the illumination beam path is present because this further increases the number of wavelength distributions that can be generated . a sixth exemplary embodiment of the illumination device according to the invention is illustrated in fig6 . this exemplary embodiment is similar to the exemplary embodiment described with reference to fig3 in such a way that use is made of an illumination device with an intermediate image , i . e . an illumination device with a collector optical system 27 . the exemplary embodiment illustrated in fig6 differs from the exemplary embodiment described with reference to fig3 in that use is made of a stop wheel 9 , as was also used in the first exemplary embodiment described with reference to fig1 . in the present exemplary embodiment , the stop wheel 9 is situated in the region of a plane conjugate to the object plane of the observation object 7 , and so the stops 11 , 13 of the stop wheel constitute radiant field stops . additionally there may be an aperture stop , as illustrated in fig3 . instead of at the location of a radiant field stop or in the vicinity of the location of a radiant field stop , the stop wheel can be arranged at the location of an aperture stop or in the vicinity of the location of an aperture stop . this also holds true for other exemplary embodiments in which use is made of a stop wheel . fig7 shows a further exemplary embodiment of an illumination device according to the invention , in which there is an intermediate image of the light - emitting diode 1 . the design of the illumination optical system corresponds to the design described with reference to fig3 , with the difference that there is no converter - element wheel . rather , a converter element 55 is fixedly arranged in the illumination beam path of the observation device . the exemplary embodiment illustrated in fig7 constitutes an exemplary embodiment for the device according to the invention with an intermediate image , having a particularly simple design . a further exemplary embodiment of an illumination device with an intermediate image is illustrated in fig8 . this exemplary embodiment is similar to the third exemplary embodiment , described with reference to fig3 , except for the fact that instead of a single light - emitting diode 1 and a converter - element wheel 31 , it is equipped with a light - emitting diode wheel 49 with at least two light - emitting diodes 51 , 53 , which differ from one another in respect of the spectral wavelength distribution of the light emitted by them . the light - emitting diodes 51 , 53 can be alternately introduced into the illumination beam path with the aid of the light - emitting diode wheel 49 . it goes without saying that the light - emitting diode wheel 49 can also have more than two light - emitting diodes 51 , 53 . however , additionally the exemplary embodiment illustrated in fig8 may also have one or more converter elements that can be introduced into the beam path in order to further increase the number of possible spectral wavelength distributions of the illumination light . a further exemplary embodiment of an illumination device according to the invention without an intermediate image is illustrated in fig9 . this exemplary embodiment is similar to the first exemplary embodiment , described with reference to fig1 , except for the fact that instead of the stop wheel 9 with the stops 11 , 13 and the converter elements 15 , 17 a fixed radiant field stop 55 , to which a converter element 57 is also attached , is arranged in the illumination beam path . the exemplary embodiment illustrated in fig9 constitutes a particularly simply designed illumination optical system according to the invention . a further exemplary embodiment for an illumination optical system according to the invention without an intermediate image is illustrated in fig1 . this exemplary embodiment also constitutes a modification of the exemplary embodiment described with reference to fig1 . instead of the stop wheel 9 with stops 11 , 13 and converter elements 15 , 17 arranged thereon , there is a fixed stop like in the above - described ninth exemplary embodiment . however , in contrast to the ninth exemplary embodiment , no converter element 57 is arranged on the fixed radiant field stop . instead , there is a light - emitting diode wheel 49 , as was described with reference to fig5 . said wheel comprises at least two light - emitting diodes 51 , 53 , which differ from one another in respect of the spectral wavelength distribution of the light emitted by them . the light - emitting diodes 51 , 53 can be alternately introduced into the illumination beam path in order to implement different spectral wavelength distributions of the illumination light . fig1 shows a further exemplary embodiment for an illumination device according to the invention with an intermediate image . the exemplary embodiment merely differs from the exemplary embodiment shown in fig3 in that , as an aperture stop , there is a double stop 59 with two stop openings instead of a single stop . the double stop 59 makes it possible to implement coaxial illumination . a further exemplary embodiment of an illumination device according to the invention without an intermediate image is illustrated in fig1 . this exemplary embodiment is similar to the exemplary embodiment illustrated with reference to fig9 . however , instead of a single stop 55 with a converter element 57 arranged thereon , use is made in the twelfth exemplary embodiment of a double stop 61 with a converter element 63 arranged thereon as a radiant field stop . moreover , there are two light - emitting diodes 1 a , 1 b which produce the illumination light as luminescence emitters . the arrangement described in fig1 makes it possible to implement coaxial illumination . a further exemplary embodiment of an illumination device according to the invention without an intermediate image is illustrated in fig1 . in its design , this exemplary embodiment is similar to the first exemplary embodiment , described with reference to fig1 . the difference merely consists of the fact that instead of the stop wheel 9 with individual stops 11 , 13 and converter elements 15 , 17 arranged thereon , there is a stop wheel 65 with at least two double stops 67 , 69 and , arranged upstream of the double stops 67 , 69 in the beam path , converter elements 71 , 73 . this stop wheel 65 makes it possible to implement the already discussed coaxial illumination . a further exemplary embodiment of an illumination device according to the invention with an intermediate image is illustrated in fig1 . this illumination device largely corresponds to the sixth exemplary embodiment , described with reference to fig6 , with the difference that the stop wheel 9 with the individual stops 11 , 13 is replaced by a stop wheel 65 , as was described with reference to fig1 . the double stops 67 , 69 can be used to implement coaxial illumination beam paths . a further exemplary embodiment of an illumination device according to the invention without an intermediate image is illustrated in fig1 . this illumination device largely corresponds to the illumination device described with reference to fig1 , with the difference that instead of the single stop 55 there is a double stop 75 , with the aid of which coaxial illumination can be implemented . a further exemplary embodiment of an illumination device according to the invention with an intermediate image is illustrated in fig1 . this exemplary embodiment is similar to the exemplary embodiment shown in fig8 . however , the single stop 29 present in fig8 is replaced by a double stop 77 in order to implement coaxial illumination . otherwise the exemplary embodiment shown in fig1 does not differ from the exemplary embodiment shown in fig8 . as an example of a medical - optical observation instrument with an illumination device according to the invention , a surgical microscope is illustrated in a schematic lateral view in fig1 and in a schematic plan view in fig1 . in addition to two light - emitting diodes 77 a , 77 b or other luminescence emitters as light sources and an eye as an observation object 7 , fig1 and 18 show an illumination optical system 79 , which comprises a collector optical system 81 and a condenser optical system 83 , the main objective 85 of the surgical microscope and — as functional blocks — a magnification - setting apparatus 87 and a binocular tube 89 of the surgical microscope . the main objective 85 is primarily part of the observation optical system of the surgical microscope . however , since the illumination beam path 90 also passes through it in the present exemplary embodiment and thus contributes to projecting the illumination light onto the observation object 7 , it can moreover be considered part of the illumination optical system 79 . in the present exemplary embodiment , both the collector optical system 81 and the condenser optical system 83 are made of lens groups in order to largely reduce image aberrations in the illumination beam path 90 . the illumination beam path 90 is coupled into the main objective 85 via a beamsplitter 91 , for example a partly transparent mirror , and routed to the observation object 7 via the main objective 85 . in addition to the illumination beam path 90 comprising the optical elements : collector 81 , condenser 83 , beamsplitter 91 and main objective 85 , the surgical microscope has an observation beam path 92 . the latter , starting from the observation object 7 , runs through the main objective 85 and the beamsplitter 91 , with , in contrast to the illumination beam path 90 , the observation beam path 92 not being deflected by the beamsplitter 91 . moreover , a reflection stop 84 is arranged in the illumination beam path 90 on the light - source side of the beamsplitter 91 , which reflection stop prevents reflections of the illumination being reflected into the observation beam path 92 . in the observation beam path 92 , the magnification - setting apparatus 87 adjoins the beamsplitter 91 ; it makes it possible to set the magnification factor used to perform a magnification in the observation beam path 92 . in particular , the magnification - setting apparatus 87 may be embodied as a zoom system , in which there are at least three lenses or lens groups , with two lenses or lens groups being displaceable along the optical axis such that the magnification factor can be set in a continuous fashion . alternatively , it is also possible to embody the magnification - setting apparatus 87 as a discrete magnification changer . in the latter , there are a plurality of lens arrangements , with the lenses in a lens arrangement being fixed in a fixedly prescribed position with respect to one another . in such a discrete magnification changer , the magnification factor is changed by alternate introduction of different such lens arrangements into the observation beam path 92 . the magnification - setting apparatus 87 may already by embodied as a two - channel optical system , i . e . it has a left and a right stereoscopic partial beam path , with each partial beam path having its own optical elements . however , alternatively , the magnification - setting apparatus 87 may also be embodied as a so - called “ large optical system ”, i . e . the optical elements thereof are so large that both stereoscopic partial beam paths pass through them at the same time . then a purely optical or an optical / electronic binocular tube 89 adjoins the magnification - setting apparatus 87 . in the case of a purely optical binocular tube 89 , a tube objective and an eyepiece are arranged in each stereoscopic partial beam path . the tube objectives are used in each case to produce intermediate images in the stereoscopic partial beam paths , which intermediate images are imaged at infinity by means of the eyepiece optical system such that an observer can observe the intermediate images with a relaxed eye . in the case of a combined optical and electronic binocular tube 89 , there is an imaging optical system in each stereoscopic partial beam path and it images the observation object 7 on two electronic image sensors . in the present exemplary embodiment , the illumination device of the surgical microscope is embodied as so - called köhler illumination . here the light - emitting diodes 77 a , 77 b are imaged in an intermediate image plane in which there is an aperture stop 93 , the latter being used to be able to set the brightness of the illumination in a targeted fashion . furthermore , there is a radiant field stop 95 , which is situated in the observation beam path 92 in a plane conjugate to the object pane of the observation object 7 . objects that are arranged in such a conjugate plane are imaged in a sharply defined fashion in the object plane . hence the radiant field stop 95 can be used to implement a sharp delimitation of the illuminated field in the object 7 . overall , a köhler optical system makes it possible to generate a sharply delimited homogeneous illuminated field in the object 7 . in terms of its basic design , the illumination optical system illustrated in fig1 and 18 corresponds to the illumination optical system described in de 10 2006 013 761 a1 , with the difference that two light - emitting diodes serve as light sources 77 a , 77 b instead of the optical fiber emergence end described in said document . the illumination optical system 79 is embodied as a large optical system , i . e . both the partial beam path 90 a starting at the light - emitting diode 77 a and the partial beam path 90 b starting at the light - emitting diode 77 b pass through the collector optical system 81 and the condenser optical system 83 ( see fig1 ). only the aperture stop 93 situated in the intermediate image plane of the illumination optical system 79 and the radiant field stop 95 situated in the plane conjugate to the object plane are embodied as double stops , i . e . they each have an individual stop opening for each partial beam path 90 a , 90 b of the illumination . blue light - emitting diodes are used as light - emitting diodes 77 a , 77 b in the present exemplary embodiment . in order nevertheless to be able to provide broad - band — and in particular white — illumination light , at least one converter element 97 , 98 , 99 , 100 , 101 , 102 is introduced into the illumination beam path 90 . said converter element is preferably designed to be easily replaceable such that the spectral wavelength distribution in the illumination light can be changed by replacing the at least one converter element . possible positions for arranging the at least one converter element 97 , 98 , 99 , 100 , 101 , 102 are specified in fig1 and 18 . it should be noted that the six converter elements 97 to 102 are merely sketched for characterizing the possible positions . typically only one of the six sketched converter elements is present . in particular , it can be arranged in or in the vicinity of the radiant field stop 95 , as indicated in fig1 and 18 by the converter elements 97 and 98 . the at least one converter element 97 , 98 , 99 , 100 , 101 , 102 comprises a converter phosphor selected such that it converts at least part of the light from the light - emitting diodes 77 a , 77 b into light with a longer wavelength . in order to produce e . g . white light from the blue light of the light - emitting diodes 77 a , 77 b in the present exemplary embodiment , the converter phosphor of the converter element is selected such that it converts part of the blue light into yellow light such that the superposition of the yellow light on the remaining blue light yields white light . however , it may also be selected such that it converts all the light from the light - emitting diodes 77 a , 77 b into light of one or more longer wavelengths , particularly if the light - emitting diodes 77 a , 77 b emit light in the ultraviolet spectral range instead of light in the visible spectral range . in order to produce a broad wavelength distribution , the converter element can then comprise a mixture of a plurality of converter phosphors . however , alternatively it is also possible for at least two converter elements 97 , 98 , 99 , 100 , 101 , 102 with different converter phosphors to be arranged in the illumination beam path 90 . by way of example , in order to produce white light from the ultraviolet light , the ultraviolet light can partly or wholly be converted into blue light by a first converter element with a first converter phosphor . a second converter element with a second converter phosphor then converts the remaining ultraviolet light or part of the blue light into green light and / or yellow light and / or red light . the superposition of the blue light on the green light and / or the yellow light and / or the red light then yields broad - band light . more particularly , this can yield white light . alternatively , use can also be made of merely a single converter element for producing the white light from the ultraviolet light , said converter element containing a mixture of the two converter phosphors . the at least one converter element 97 , 98 , 99 , 100 , 101 , 102 can moreover have an entry area which faces the light - emitting diodes 77 a , 77 b and is provided with a dichroic layer that is transparent to light with the wavelength distribution of the unconverted light entering the converter element 97 , 98 , 99 , 100 , 101 , 102 . by contrast , this dichroic layer is highly reflective for converted light directed in the direction of the light - emitting diodes 77 a , 77 b . this can increase the efficiency of the conversion . such a dichroic layer may also be present in the converter elements in the other exemplary embodiments .
an illumination device for a medical - optical monitoring apparatus illuminates a monitored object with illumination light via an illumination beam path . the illumination device has at least one luminescence emitter as a light source as well as at least one converter element separated from the luminescence emitter , is provided with a converter luminescent substance for converting at least some of the wavelength distribution of the light emitted by the at least one luminescence emitter . the converter element is or can be introduced into the illumination beam path .