White light source and intraocular illumination device

Abstract

The present invention relates to a white light source and an endoocular illumination device including the white light source. In particular, the present invention relates to a white light source for fiber-based endoocular illumination using light with a controllable broad spectral composition, and an endoocular illumination device with corresponding controllability. The white light source (100) for fiber-based endoocular illumination with light of controllable spectral composition according to the present invention comprises at least two light sources (10, 20, 30), which provide light beams of different colors (preferably predominantly components of the blue, green, and red spectral ranges). These individual light beams are combined into a common light beam (W), and the white light source (100) is designed to individually control the proportions of the individual light beams in the common light beam (W). At least one of the light sources (10, 20, 30) includes a laser-pumped remote phosphor (LARP) light source (90) with a phosphor as a conversion element (98), configured to excite the conversion element (98) with excitation radiation (S) emitted by a laser diode (92).

Description

[Technical Field]

[0001] The present invention relates to a white light source and an intraocular illumination device including the white light source. In particular, the present invention relates to a white light source for fiber-based intraocular illumination with light of a controllable spectrally broad composition, and an intraocular illumination device with corresponding controllability. [Background technology]

[0002] For example, to illuminate the interior of the eye during posterior segment surgery, light is delivered to the eye using light guides, such as optical fibers or other fibers. In this regard, within the scope of the present invention, the term "fiber" is used synonymously with "light guide." These fibers have as small a diameter as possible and are introduced into the interior of the eye where surgery is to be performed. For this purpose, the fiber is introduced into the vitreous humor through a small incision at the edge of the eye. In this regard, the distal end of the fiber can take different forms (e.g., a lensed fiber) depending on the respective illumination requirements, so that the posterior segment can be illuminated either in a point-like or a broad manner according to the requirements of the respective surgery. Since the incision in the eye should be kept as small as possible, there is an upper limit to the allowable fiber diameter. Again, this means that the highest possible luminous flux should be able to be introduced into the eye through the fiber to ensure optimal illumination of the surgical field. Therefore, a fundamental objective of an intraocular illumination device is to be able to deliver a very large amount of light to the eye using as small a fiber diameter as possible.

[0003] Another objective of such devices is to provide a highly adaptable spectral composition of light for each application. This is particularly relevant for the ability to adjust the spectral content (color temperature) of white light, as is often required. A corresponding light source that provides light with a controllable, spectrally broad composition substantially within the visible spectral range (VIS spectral range) is called a spectrally controllable white light source. Within the scope of the present invention, the terms "controllable" and "controllably" are to be understood to refer specifically to both open-loop and closed-loop control. Furthermore, the light, however, should also be able to provide good color rendering. To this end, the lighting device should be able to provide a color space with a spectrum covering the visible spectral range as large and as continuously as possible. Ophthalmologists often make decisions based solely on subtle shades. Since these shades can only be observed and evaluated, the light used for illumination purposes should contain the corresponding wavelengths. In particular, a natural reproduction close to the sunlight spectrum (or how it appears through the respective surgical microscope) is preferred. If possible, medical decisions in this regard should not be based on different lighting conditions.

[0004] Until now, xenon and halogen lamps have been the primary light sources used. Light-emitting diodes (LEDs) are also used as an alternative. In this case, white light is typically produced by phosphors, known as white LEDs, which emit spectrally broad light when excited with blue light. Additional white light sources, in which light emitted by red, green, and blue LEDs is mixed to form white light, are used in particular lighting devices. In both cases, the amount of light that can be coupled into the optical fiber is limited, in particular, by the correspondingly low étendue of the emitted light. The proximal fiber end and its surroundings can melt and be destroyed if the power density is too high. Furthermore, when phosphorus-based white LEDs are used, the color temperature of the emitted light cannot be controlled due to the specific conversion properties of the phosphors used. Therefore, the emitted light must first be split into its individual spectral components (e.g., by appropriate spectral filter elements) and then recombined according to their respective spectral requirements.

[0005] Laser diodes (LDs) can also be used instead of LEDs. Again, light emitted by red, green, and blue LDs can be mixed to form white light. However, such white light has a significantly reduced spectral bandwidth compared to comparable LEDs, resulting in very limited color rendering. However, an advantage of using LDs as a light source is their very high étendue, which allows efficient coupling of the emitted light into even very small fiber diameters. Another drawback is the strong coherence of the emitted radiation, which can cause troublesome interference effects and require consideration of laser protection standards. Adding a diffuser or other element to reduce the coherence of the radiation can mitigate this, but this leads to even more losses and a lower étendue.

[0006] Meanwhile, LARP white light sources (laser-activated remote phosphor light sources) have been developed, applying the conversion principle known from LEDs to laser diodes. In this case, the radiation emitted by the laser diode is focused onto a phosphor as a conversion element, where it is converted to the corresponding white spectrum and then focused again by an associated focusing optical unit. Point-like excitation largely preserves the high étendue of the laser radiation during the conversion process, while the short coherence of the excitation radiation is largely lost during the conversion process. Compared to the use of LEDs, such LARP white light sources allow significantly higher light intensities to be coupled into fibers with diameters much smaller than 0.5 mm. In this regard, known LARP white light sources generate high-étendue, virtually coherent light. However, LARP white light sources have not been used to date for intraocular illumination. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Patent No. 102005054184B4 Summary of the Invention [Problem to be solved by the invention]

[0008] The problem solved by the present invention is therefore to specify a white light source and an intraocular illumination device that can provide light with a particularly high etendue, low coherence, and a controllable spectrally broad composition for fiber-based intraocular illumination. [Means for solving the problem]

[0009] According to the invention, these problems are solved by the features of the independent claims 1 and 12. Advantageous configurations of the invention are contained in the respective dependent claims.

[0010] One aspect of the present invention relates to a white light source for fiber-based intraocular illumination with light of controllable spectral composition, which includes at least two light sources for providing different colored light beams, preferably having components substantially in the blue, green, and red spectral ranges, the individual light beams being combined to form a composite light beam, the white light source being configured to individually control the proportion of the individual light beams in the composite light beam, and at least one of the light sources being a laser-activated remote phosphor light source, or LARP light source, having phosphor as a conversion element and a laser diode for exciting the conversion element with excitation radiation emitted by the laser diode.

[0011] Preferably, the white light source includes one light source each for providing a monochromatic light beam having a respective component substantially within the blue, green, and red spectral ranges, and preferably includes a beam combiner for combining the individual light beams to form a composite light beam.

[0012] In particular, the present invention relates to a white light source for fiber-based intraocular illumination with light of controllable spectral composition, comprising: one light source each for providing a monochromatic light beam having a respective component substantially within the blue, green, and red spectral ranges; and a beam combiner for combining the individual light beams to form a composite light beam, wherein the white light source is configured to individually control the proportion of the individual light beams in the composite light beam; and at least one of the light sources is a laser-activated remote phosphor light source, or LARP light source, having a phosphor as a conversion element and a laser diode that excites the conversion element with excitation radiation emitted by the laser diode.

[0013] In this case, a white light source refers to a light source that, at least in principle, has as wide a spectral distribution as possible to enable as perfect a color rendering as possible, and is therefore suitable for providing white light whose emitted white spectrum appears as a mixture of red, green, and blue spectral components. In this case, the spectral components can be characterized in particular as narrow-band separations (e.g., when LDs of different colors are used) or by at least one continuous spectral band (e.g., when white LEDs or white larps are used). In this case, the adaptation of the overall white spectrum in terms of the intensities of the individual components or their spectral distribution is called the controllability of the spectral components.

[0014] Therefore, the white light source according to the present invention is an RGB light source, and its RGB composition can be selected as freely as possible. In particular, the white light source according to the present invention should also be designed to provide bicolor or monochromatic light from only two or only one light source by corresponding downregulation and / or filtering of a light source or individual light sources from the included light sources. For example, in this case, one light source can also be designed to emit bicolor light, i.e., light of different colors having components in substantially two spectral ranges within the group of blue, green, and red spectral ranges. However, preferably, one light source according to the present invention for providing white light by combination emits only monochromatic light, i.e., monochromatic light having components in substantially one spectral range within the group of blue, green, and red spectral ranges, for better controllability.

[0015] A white light source according to the present invention includes a light source for providing a monochromatic light beam having respective components substantially within the blue, green, and red spectral ranges. In this context, the term "monochromatic" refers specifically to the associated spectral range of each light source resulting in a color impression for the observer. In this context, the wavelength ranges of approximately 640 nm to approximately 780 nm, approximately 490 nm to approximately 570 nm, and approximately 430 nm to approximately 490 nm are commonly referred to as red, green, and blue, respectively. Corresponding transition regions (e.g., greenish-blue, yellowish-green, and yellowish-orange) are distinguished between these wavelength ranges. Because the human eye only has receptors for light within these wavelength ranges, this entire range is also referred to as the visible spectral range (VIS spectral range). The violet (wavelength range of approximately 380 nm to approximately 430 nm) and ultraviolet spectral range (UV spectral range starting at wavelengths below approximately 380 nm) are adjacent below the blue spectral range. The infrared spectral range (the IR spectral range beginning at wavelengths above about 780 nm) is adjacent to and above the red spectral range.

[0016] Therefore, "monochromatic light" within the meaning of the present invention is defined by its color impression, encompassing a relatively broad spectrum (from the respective assigned spectral ranges) and therefore extending beyond the boundaries of the individual spectral ranges. Therefore, monochromatic light within the scope of the present invention should also be understood to mean, for example, light within the reddish-yellow, bluish-green, or purplish-blue spectral ranges. In contrast, the term "monochromatic light," as commonly known in the art, refers to light whose spectrum essentially contains only one wavelength (or a very narrow range around a specific central wavelength). A laser diode with an emission wavelength of 680 nm emits substantially monochromatic light, whereas a red light-emitting diode transmits spectrally relatively broad monochromatic (but not monochromatic) red light, with a component essentially within the red spectral range.

[0017] Depending on the spectral width of the light source, as mentioned above, the individual light beams may also contain secondary spectral components that deviate from the actual emitted spectrum and lie outside the actual or directly adjacent spectral ranges (e.g., excitation or primary light in the case of light source conversion), and thus the respective components are also defined as being substantially within the blue, green, and red spectral ranges. This case depends in particular on the respective color impression of the observer, but there may also be boundaries according to the relative intensity ratios of the individual spectral ranges of the emitted light.

[0018] A color impression can be quantitatively described by what is known as the "dominant wavelength" of the corresponding light. The dominant wavelength of light can be identified based on the corresponding color space representation as the intersection of a line defined by the color points of the light source and the white point closest to the edge of the color gamut. Narrow-bandwidth or single-frequency light sources tend to be located at the edge of the color gamut, while broader-bandwidth light sources tend to be located in the center of the color gamut. The dominant wavelength defines the wavelength at which the emitted light is perceived as dominant by the human eye. For example, a monochromatic light beam having components substantially within the red spectral range can therefore be located near the red edge of the color gamut, with its dominant wavelength lying between approximately 640 nm and approximately 780 nm. Corresponding statements apply to each of the other colors of light.

[0019] A beam combiner may be an optical component or device for combining individual light beams to produce a composite light beam. For example, such a beam combiner may take the form of a cube-shaped element, in which input beams are coupled into the optical element via three different sides and a common beam is coupled out at an associated fourth side ("X-cube"). Corresponding beam combiners may also be provided that are entirely fiber-based (known as fiber combiners). Another embodiment of a beam combiner is disclosed in U.S. Pat. No. 5,649,393. Beam combiners are part of the prior art and are therefore well known to those skilled in the art.

[0020] The white light source according to the present invention is configured to individually control the proportion of the individual light beams in the combined light beam. This means, for example, that the intensity of the individual light sources can be individually controlled, or that the white light source according to the present invention allows the individual light beams to be controllably attenuated after they are provided by the individual light sources. For this purpose, electronic control can be provided to individually control the components of the individual light sources in the combined light beam. In the simplest case, the control can relate directly to the light generation in the individual light sources, for example, open-loop control of the operating current, which serves for closed-loop control of the intensity of the light emitted by the individual light sources. However, electronic control also relates to optical control of the light intensity after providing the light beam. Therefore, individual control relates to all means and measures suitable for varying the components of the individual light sources and is not limited to one type of intensity control.

[0021] According to the invention, at least one of the light sources is a LARP light source having a phosphor as a conversion element and a laser diode for exciting the conversion element with the excitation radiation emitted by the laser diode. LARP light sources are part of the prior art and are well known to those skilled in the art. Particularly preferably, all light sources of the white light source according to the invention take the form of a LARP light source.

[0022] The advantage of LARP light sources lies in their large étendue combined with high light intensity when the light coherence is low. As a result, high power can also be efficiently coupled into small fiber diameters without coupling losses that would lead to unacceptable temperature increases and, consequently, melting of the proximal end of the utilized fiber used for coupling purposes. By using LARP light sources, at least the spectral components associated with these sources can be coupled into the corresponding fiber with higher efficiency than light from other light sources. If only LARP light sources are used in the white light source according to the present invention, the maximum light intensity that can be coupled into the corresponding fiber can be significantly increased compared to other white light sources from the prior art.

[0023] Therefore, according to the present invention, it is preferable to mix three LARP light sources with individual red, green, and blue spectrums. In this regard, each spectrum tends to be narrowband compared to the overall spectrum of a typical white LED, but much broader compared to a mixed RGB laser configuration. In particular, this can be used to generate very broad red, green, and blue spectral components so that they can be mixed and individually controlled. The larger spectral bandwidth of the LARP light source also results in good to very good color rendering. By dividing the power components among these three light sources, it is also possible to have higher power, especially when using conventional white LEDs. Furthermore, unlike direct white light emitters with continuous broadband spectra, by providing the color components individually, a narrower overall spectrum can be generated in a targeted manner, thereby improving the light output-to-bandwidth ratio. Individual light beam components can be tuned or controlled to specific color positions through electronic control. In particular, the individual disadvantages of previous technologies can be complemented or compensated for by the advantages of each of the other technologies. LARP technology eliminates drawbacks caused by typical laser characteristics such as long coherence length, laser speckle, poor color rendering, and other necessary classifications of lasers.

[0024] Preferably, the conversion element includes auxiliary phosphors for adapting the conversion element to the excitation radiation of the laser diode. Depending on the laser diode used to excite a particular phosphorus as a conversion element, it may be advantageous to include what are known as auxiliary phosphors in the phosphor composition or to use such auxiliary phosphors in the corresponding assembly. The excitation radiation from the excitation laser diode, which may not be optimally designed from a spectral standpoint, can further be adapted to the specific absorption characteristics of the phosphorus used for the desired target spectrum. Thus, the excitation radiation can be adapted by the auxiliary phosphors. However, preferably, the conversion element can also include multiple phosphors to specify a specific converted color spectrum. In particular, this can increase the bandwidth of the converted light. Since the individual phosphors can be mixed with each other during production, they are present as evenly distributed as possible within the conversion element. For example, the spectral distribution of a LARP light source emitting in the red, green, or blue spectral range can be specifically adapted to the required lighting needs by the phosphorus mixture used in the conversion element.

[0025] Preferably, at least one LARP light source is designed to emit white light. Adapting the spectral bandwidth or spectral curve of the emitted white light to provide a corresponding monochromatic light beam can be achieved by a spectral filter element between the corresponding LARP light source and the beam combiner or as an element of the beam combiner. This means that the broad spectral distribution of the emitted light from the white-light LARP is reduced or modified by an additional spectral filter element. The spectral distribution downstream of the spectral filter element then appears as the product of the spectral distribution of the white-light LARP and the spectral curve of the transmission range of the spectral filter element. Within the scope of the present invention, it is preferable to provide multiple, and in particular two, transmission ranges. For example, for regulatory and / or legal reasons, the scope of the present invention may also include the placement of an additional filter in the combined or blue light beam to further reduce the proportion of the blue component incident on the eye. This can extend the duration of the surgical procedure.

[0026] White-light LARP typically has a very broad spectrum, achieving very good color rendering even after spectral filtering. However, a drawback of this configuration is that, as a result of filtering, only a fraction of the original light intensity is available for input coupling into the optical fiber because some of the white light is filtered out by the spectral filter element. The spectral filter element can also be integrated directly into the housing of the LARP light source (monochromatic LARP light source). The spectral filter element can also take the form of a beam combiner element, such as a dielectric filter layer attached directly to the surface of the beam combiner or to an internal interface of the beam combiner. Preferably, the beam combiner provides lossless spectral mixing, even when losses may occur, and the input powers are summed.

[0027] Preferably, at least one LARP light source is directly designed to provide the relevant color light beam. Preferably, the relevant color light beam is directly provided by an adapted combination of phosphors and laser diodes in the at least one LARP light source. Unlike the embodiment with additional spectral filter elements described in the previous paragraph, in this case, a LARP light source that already emits a single color is used. In particular, this can be achieved by a phosphor conversion element that converts the corresponding excitation radiation into only a very specific spectral range. For this purpose, multiple heat-resistant phosphors for different spectral ranges are available. However, the spectral distribution from the LARP light source directly designed to provide the relevant color light beam can be further adapted by a spectral filter element. In this case, the intensity loss in the spectral filter element can be significantly reduced compared to white light LARP, which is filtered at a single wavelength.

[0028] Preferably, the provision of the color light beam having a component substantially in the blue spectral range is achieved by a diode, LED, or laser diode, LD, emitting light substantially in the blue or violet spectral range. The provision of the color light beams having components substantially in the red and green spectral ranges is preferably achieved by one LARP light source each. This configuration is preferred because the blue or violet spectral range is less necessary for color mixing and can therefore be achieved directly, for example, by LEDs. The construction costs of the white light source according to the invention can be reduced in this way, particularly since LEDs and LDs are much cheaper than the corresponding LARP light sources, and the substitution of said LARP light sources in the blue spectral range does not result in any substantial disadvantages.

[0029] Preferably, the provision of a colored light beam having a component substantially in the blue spectral range is performed by a laser diode emitting light substantially in the blue or violet spectral range. Additionally, a conversion element for providing a monochromatic light beam having a component substantially in the cyan spectral range can be implemented by a laser diode (LARP light source in the cyan spectral range).

[0030] For example, the use of monochromatic light in the cyan spectral range can enable direct activation of fluorescein fluorescence in the eye and / or can be used to obtain better color rendering values. The cyan spectral range is not uniformly defined in the prior art, but is generally assigned to a wavelength range of approximately 482 nm to 494 nm, particularly 487 nm to 492 nm. Spectrally, therefore, the cyan spectral range is at the low-energy end of the blue spectral range or very close to the green spectral range.

[0031] Since light in the blue spectral range has higher energy than light in the green spectral range, the cyan spectral range can be provided in particular by conversion from blue or violet light using phosphors ("cyan phosphors"). As mentioned above, since the blue spectral range is usually only needed to a small extent for color mixing, a LARP light source for providing a monochromatic light beam having a component substantially in the cyan spectral range can therefore be realized using a component of blue laser radiation generated. In this case, the light beam having a component substantially in the blue and cyan spectral ranges has a common optical path toward the beam combiner. The white light source according to the invention therefore first generates a larger amount of blue or violet light internally than is necessary for a specific, predetermined correlated color temperature (CCT). This amount can then be converted by cyan phosphors to obtain white light or filtered color light with precisely specified characteristics.

[0032] Preferably, the white light source according to the present invention further comprises a LARP light source as a light source for providing a monochromatic light beam having a component substantially in the cyan spectral range, the individual light beams being combined by a beam combiner to form a composite light beam, and the individual light beams have separate optical paths. Except for the independence of the light sources for providing the monochromatic light beam having a component substantially in the blue spectral range, this embodiment substantially corresponds to the embodiment described in the previous paragraph, and therefore the description therein applies accordingly. In this case, the associated beam combiner must be able to combine four monochromatic light beams on separate optical paths into a composite light beam.

[0033] Preferably, the white light source according to the invention further comprises a sensor (fault sensor, in particular integrity sensor) for monitoring at least one LARP light source. The phosphorus used in the conversion element is subjected to high temperature loads, which may lead to destruction and failure of the phosphorus structure if overloaded. The intensity of the emitted light may consequently drop sharply, and therefore isolation of a suitable sample light for continuous or repeated monitoring of the light power is advantageous.

[0034] However, it may also occur under certain circumstances that the laser radiation used to excite the conversion element is unintentionally reflected and directly coupled into the illumination device. Blue laser radiation in particular can have a highly damaging effect on biological tissue structures and cells, especially the retina and optic nerve of the eye, making it necessary to immediately shut off the illumination device or the excitation laser, or at least block the damaging radiation components. This can be done by suitable power monitors of the light beam and / or by evaluating the spectral characteristics of the provided light beam. For example, if a significant increase in the spectral range of the excitation radiation is detected, an appropriate automated reaction can occur.

[0035] Thus, the sensor may be designed in particular to monitor the intensity of the energy-rich blue or violet components in the provided spectrum. If a sudden, significant increase in intensity is registered for these components, a safe shutdown of the excitation of at least the corresponding LARP light source or a complete downregulation of the corresponding LARP light source or of the entire white light source according to the invention may be performed. Alternatively, it is also possible to measure and monitor the ratio of the intensity of the provided white light (or of the overall intensity in the case of monochromatic or polychromatic light deviating from white light as a result of a corresponding control of the white light source according to the invention) to the blue spectral component. The sensor may be positioned at a suitable position in the beam path of the white light source according to the invention.

[0036] Another aspect of the present invention relates to an intraocular illumination device, which includes a white light source according to the present invention, an optical fiber for intraocular illumination, and fiber coupling means (optical system) for coupling a combined light beam into a proximal end of the optical fiber.

[0037] Preferably, the optical fiber has an effective diameter of 0.1 mm or less and is capable of emitting a luminous flux of greater than 1 lm at its distal end.

[0038] The optical power required for an intraocular illumination device is approximately 1 lm to 40 lm. This depends on the individual situation, the tools used, and the patient's specific ocular condition. Using a conventional LED light source, prior art techniques allow for a maximum coupling of approximately 20 lm into a 23G fiber with an effective diameter of 0.486 mm and an NA of 0.5. Scaling linearly, this means that a comparable fiber with the same NA and a conventional LED light source, with an effective diameter of 0.1 mm, can only couple a maximum of approximately 0.85 lm. Due to the high etendue of at least one LARP light source, this value can be significantly increased by the white light source according to the present invention. Consequently, with a preferred fiber effective diameter of approximately 0.05 mm to 0.1 mm, it is possible to couple at least 1 lm, preferably 2 lm to 3 lm, and even more preferably up to 30 lm into each fiber.

[0039] Further preferred configurations of the invention result from the features specified in the respective dependent claims.

[0040] The various embodiments of the invention presented in this application can be advantageously combined with one another, unless expressly stated otherwise.

[0041] The invention will now be described in exemplary embodiments with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0042] [Figure 1] 1 shows an exemplary schematic diagram of a fiber-coupled LARP light source according to the prior art. [Figure 2] 1 shows an exemplary schematic diagram of a first embodiment of a white light source according to the present invention having three independent light sources. [Figure 3] FIG. 1 shows an exemplary schematic diagram of a LARP light source for providing two monochromatic light beams. [Figure 4] 2 shows an exemplary schematic diagram of a second embodiment of a white light source according to the present invention having four independent light sources. [Figure 5] 1 shows an intraocular illumination device according to the present invention. [Figure 6] 1 shows a typical spectrum of a white light LED. [Figure 7] A typical spectrum for a white light larp is shown. DETAILED DESCRIPTION OF THE INVENTION

[0043] FIG. 1 shows an exemplary schematic diagram of a prior art fiber-coupled LARP light source 90. In this case, excitation radiation S emitted by a laser diode 92 (pump laser) is deflected, for example, by a dichroic mirror 94 and focused by a collection optical unit 96 onto a suitably adjusted conversion element 98. A phosphor is used as the conversion element 98 of the LARP light source 90. In this case, the phosphor is typically arranged on a substrate or carrier in the form of a heat sink. The converted light L emitted by the excitation conversion element 98 to the focal point of the collection optical unit 96 is then confocally collected and collimated by the collection optical unit 96. After passing through the dichroic mirror 94, the converted light L can be coupled into a light guide 120, for example an optical fiber, by means of a suitable fiber coupling means 110. The corresponding LARP light source 90 can be constructed individually from individual components or purchased as a fully integrated component part. For example, the illustrated LARP light source 90 represents only one possible option for constructing such a light source, and multiple other configuration options are well known from the prior art to those skilled in the art.

[0044] 2 shows an exemplary schematic diagram of a first embodiment of a white light source 100 according to the present invention, having three independent light sources 10, 20, 30. The illustrated white light source 100 for fiber-based intraocular illumination with light of controllable spectral composition includes one light source 10, 20, 30 each for providing monochromatic light beams R, G, B having respective components substantially within the blue, green, and red spectral ranges, and a beam combiner 50 (also known as an X-cube) for combining the individual light beams R, G, B to form a combined light beam W, where the white light source 100 is configured to individually control the proportions of the individual light beams R, G, B in the combined light beam W, and one of the light sources 20 is a laser-activated remote phosphor light source (LARP light source 90) having phosphor as a conversion element (see conversion element 98 in FIG. 1 ) and a laser diode (laser diode 92 in FIG. 1 ) (see above) for exciting the conversion element with excitation radiation (see excitation radiation S in FIG. 1 ) emitted by the laser diode (see above).

[0045] In particular, the illustrated LARP light sources 90 may be designed to emit white light (white-light LARP), and adaptation of the spectral bandwidth of the emitted white light to provide an associated monochromatic green light beam G may be performed by a spectral filter element 22 between the corresponding LARP light source 90 and the beam combiner 50. The spectral filter element 22 may also take the form of an element of the beam combiner 50, such as a dielectric filter layer formed directly on a surface of the beam combiner 50 or on an inner interface of the beam combiner 50. Preferably, the beam combiner 50 mixes the spectral components so that input powers add without losses when they might occur.

[0046] However, according to the present invention, at least one LARP light source 90 may also be designed to directly provide the associated color light beam, in this case a green light beam G. In particular, the associated color light beam G may be directly provided by an adapted combination of phosphor and laser diodes within the at least one LARP light source 90.

[0047] Furthermore, an optional additional sensor 60 is depicted in the beam path for monitoring at least one LARP light source 90; for example, the sensor can separate components of the combined light beam W into detectors configured to monitor specific spectral range intensities. If a sudden increase in light intensity is identified, the white light source 100 according to the present invention can be down-regulated or down-controlled accordingly to protect the user or patient (fault sensor, in particular an integrity sensor for monitoring the conversion element). In the case of open-loop control, it is possible to set a specific value of the light intensity to be provided. In the case of closed-loop control, the system behavior can be identified at a specific time and controlled accordingly. The sensor can be placed at an appropriate position in the beam path of the white light source according to the present invention.

[0048] FIG. 3 shows an exemplary schematic diagram of a LARP light source for providing two monochromatic light beams. The basic structure of the LARP light source 90 corresponds to the embodiment shown in FIG. 1, and therefore the individual reference numerals and their assignments apply accordingly. In the figure, a color light beam B having a component substantially within the blue spectral range is provided by a laser diode 92 emitting light substantially within the blue spectral range. The laser diode 92 additionally excites a conversion element 98 for providing a monochromatic light beam C having a component substantially within the cyan spectral range. In this case, the dichroic mirror 94 can be designed as a beam splitter, so that the blue excitation light B component is reflected by the downstream reflector 32 and superimposed on the converted light generated from the monochromatic light beam C having a component substantially within the cyan spectral range at the dichroic beam splitter 98. For example, such a light source can be used as the third light source 30 for providing two monochromatic light beams (B, C) having components substantially within the blue spectral range B and the cyan spectral range C, respectively, in the embodiment of the white light source 100 shown in FIG. 2.

[0049] In an alternative embodiment of a LARP light source for providing two monochromatic light beams (e.g., cyan and blue), a particularly compact single-axis beam profile without an additional beam splitter can be achieved by using a transparent conversion element (e.g., cyan phosphorus). For example, the light of a blue LARP light source (or a white-light LARP with a high blue content) can be directly used to excite the corresponding transparent conversion element. Upon excitation, part of the transmitted blue light is then converted into cyan light, thus resulting in a superposition of the blue and cyan color components downstream of the conversion element.

[0050] 4 shows an exemplary schematic diagram of a second embodiment of a white light source 100 according to the present invention having four independent light sources. In addition to the embodiment shown in FIG. 2, the white light source 100 further includes a LARP light source (e.g., according to FIG. 1) as light source 40 for providing a monochromatic light beam C having a component substantially within the cyan spectral range, the individual light beams R, G, B, and C being combined to form a composite light beam W by a beam combiner 50, the individual light beams R, G, B, and C having separate optical paths. For example, the illustrated beam combiner 50 is a series of individual beam combiners, in which two respective input beams on separate optical paths are combined into a composite light beam.

[0051] 5 shows an intraocular illumination device 200 according to the present invention. The illustrated intraocular illumination device 200 comprises a white light source 100 according to the present invention, a light guide 120 for intraocular illumination, and fiber coupling means 110 (optical system) for coupling a combined light beam W into the proximal end of the light guide 120. Preferably, the light guide 120 takes the form of an optical fiber, which has an effective diameter of less than 0.1 mm and is capable of emitting a luminous flux of more than 1 lm at its distal end.

[0052] Figure 6 shows a typical spectrum of a white-light LED. For example, red, green, and blue light-emitting diodes can be interconnected within a common LED housing to form what is known as an RGB-LED, resulting in an externally emitted spectrum that appears white. For improved color rendering over a wider spectral range, the light components from what is known as the primary LED can also be shifted to other spectral ranges by a conversion element. Depending on the phosphor, such a conversion spectrum can extend over a spectral width of up to several hundred nanometers. In this case, high-energy blue light or light in the ultraviolet range from a suitable LED is usually used as the excitation light for the conversion.

[0053] In the illustrated spectrum, clear peaks can be identified at approximately 460 nm (blue) and approximately 630 nm (red). In contrast, the greenish-yellow spectral range from approximately 597 nm to approximately 580 nm exhibits the typical flat profile of the phosphorus conversion spectrum. The resulting white light spectrum is strongly modulated, with clearly discernible intensity drops, especially at the transitions between the individual ranges (approximately 480 nm and 600 nm). While it is possible to obtain a more uniform spectrum by attenuating the individual peaks, the overall intensity available for emission is significantly reduced in the process.

[0054] In contrast, Figure 7 shows a typical spectrum of a commercially available white-light LARP. In this case, a blue pump laser emitting at 450 nm is used to excite the conversion element. The excitation spectrum is substantially narrower than that of an LED (the spectral width in the figure is limited by the spectrometer used). A broad conversion spectrum from approximately 470 nm to approximately 700 nm can be produced by efficient excitation of the conversion element. The spectrum has a flat curve that closely resembles the solar spectrum and has no discernible modulation. This spectral curve allows for significantly improved color rendering compared to white-light LEDs or RGB LEDs due to its wider color range. Furthermore, non-spectrally overlapping excitation light can be filtered out by an appropriate low-pass filter, leaving the conversion spectrum unaffected.

[0055] Additionally, the figure plots the filter function of a bandpass filter operating in the green spectral range from about 497 nm to about 530 nm, such as may be used as the spectral filter element 22 in the light source 20 to provide a monochromatic light beam G having a component substantially within the green spectral range in the white light source 100 (see FIG. 2) according to the present invention. However, bandpass filters with substantially wider filter bandwidths may also be used. For example, for an extended green spectral range, it is possible to provide a spectral filter element with a transmission range from about 497 nm (green) to about 575 nm (greenish yellow). [Explanation of symbols]

[0056] 10 First Light Source (Red) 20 Second Light Source (Green) 22 Spectral filter element 30 Third Light Source (Blue) 32 Reflector 40 Fourth Light Source (Cyan) 50 Beam Combiner 60 Sensors (e.g., failure or integrity sensors) 90 LARP light source 92 Laser Diode (LD) 94 Dichroic Mirror 96 Condenser optical unit 98 Conversion elements (e.g., phosphorus) 100 white light source 110 Fiber coupling means 120 Light guide 200 Intraocular illumination device S excitation radiation L converted light (e.g., monochromatic, white, or hyperspectral) R First light beam (red) G Second light beam (green) B Third light beam (blue) C Fourth Light Beam (Cyan) W Combined light beam (white)

Claims

1. A white light source (100) for fiber-based intraocular illumination with light of tunable spectral composition, comprising: at least two light sources (10, 20, 30) for providing light beams of different colors, preferably having components substantially within the blue, green and red spectral ranges, the red spectral range extending between wavelengths of about 640 nm and about 780 nm, the green spectral range extending between wavelengths of about 490 nm and about 570 nm, and the blue spectral range extending between wavelengths of about 430 nm and about 490 nm; Here, the individual light beams are combined into a common light beam (W); wherein the white light source (100) is arranged to individually adjust the proportion of each light beam in the common light beam (W); wherein at least one of the light sources (10, 20, 30) is a laser activated remote phosphor light source, LARP light source, (90) having a phosphor as a conversion element (98), and a laser diode (92) for exciting the conversion element (98) with excitation radiation (S) emitted by the laser diode (92).

2. 2. The white light source (100) of claim 1, wherein the white light source (100) comprises light sources (10, 20, 30) for providing monochromatic light beams (R, G, B) having respective components substantially within the blue, green, and red spectral ranges.

3. 3. The white light source (100) of claim 1 or 2, wherein the white light source (100) comprises a beam combiner (50) for combining individual light beams into the common light beam (W).

4. 4. The white light source (100) according to claim 1, wherein the conversion element (98) comprises an auxiliary phosphor for adapting the conversion element (98) to the excitation radiation (S) of the laser diode (92) and / or the conversion element (98) comprises a plurality of phosphors for determining the converted color spectrum.

5. The white light source (100) according to any one of claims 1 to 4, wherein the at least one LARP light source (90) is designed to emit white light.

6. 6. The white light source (100) of claim 5, wherein the adaptation of the spectral profile of the emitted white light to provide the associated light beam is performed by a spectral filter element (22) between the LARP light source (90) designed to emit white light and the beam combiner (50), or by a spectral filter element (22) as an element of the beam combiner (50).

7. 5. The white light source (100) according to any one of claims 1 to 4, wherein the at least one LARP light source (90) is directly designed to provide the colored light beams (R, G, B).

8. 8. The white light source (100) of claim 7, wherein the direct provision of the colored light beams (R, G, B) is performed by a matched combination of phosphors and laser diodes (92) in the at least one LARP light source (90).

9. 9. The white light source (100) according to claim 2, wherein the provision of the colored light beam (B) having a component substantially within the blue spectral range is achieved via a diode or laser diode (92) emitting light substantially within the blue or violet spectral range, and the provision of the colored light beams (R, G) having components substantially within the red and green spectral ranges is achieved by LARP light sources (90), respectively, wherein the violet spectral range extends between wavelengths of about 380 nm and less than about 430 nm, and the blue spectral range at least partially comprises the cyan spectral range extending between wavelengths of about 482 nm and about 494 nm.

10. 10. A white light source (100) according to any one of claims 2 to 9, wherein the provision of the colored light beam (B) having a component substantially within the blue or violet spectral range is carried out via a laser diode (92) emitting light substantially within the blue or violet spectral range, the laser diode (92) additionally exciting a conversion element (98) for providing a single-color light beam (C) having a component substantially within the cyan spectral range, the violet spectral range extending between wavelengths of approximately 380 nm to less than approximately 400 nm, and the cyan spectral range extending between wavelengths of approximately 482 nm to 494 nm.

11. 10. The white light source (100) according to any one of claims 2 to 9, further comprising a LARP light source (90) as the light source (40) for providing a monochromatic light beam (C) with components substantially in the cyan spectral range, wherein a beam combiner (50) combines the individual light beams (R, G, B, C) into a common light beam (W), the individual light beams (R, G, B, C) having separate optical paths, and wherein the cyan spectral range extends between wavelengths of about 482 nm and about 494 nm.

12. An endoillumination device (200) comprising: A white light source (100) according to any one of the preceding claims; The device includes a light guide (120) for endoscopic illumination and a light guide coupling (110) for coupling a common light beam (W) to the proximal end of the light guide (120).

13. 13. The intraocular illumination device according to claim 12, wherein the light guide (120) is designed as an optical fiber, the optical fiber having an active diameter of less than 0.1 mm and capable of emitting a luminous flux of more than 1 lm at its distal end.

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