Endoscope device, correction pair arrangement, endoscope and imaging system

Abstract

The invention relates to an endoscope device (110) comprising a lens arrangement (112) which is configured to image light both in the visible range and in the near infrared range and is symmetrical with respect to a first plane of symmetry (120) perpendicular to the optical axis (114). The lens arrangement (112) comprises six rod lenses (122) and two correction elements (124), which each comprise a lens system (128) having a first lens (130) and a second lens (132). The first lens (130) is manufactured from a first glass and the second lens (132) is manufactured from a second glass. The first glass and the second glass have different Abbe numbers, with relative partial dispersions of the first glass and the second glass deviating from glass with normal dispersion in the opposite sense. The lens arrangement (112) also comprises a correction pair arrangement (134) which comprises two of the correction elements (124) symmetrical with respect to one another in relation to a second plane of symmetry (136) perpendicular to the optical axis (114).

Description

[0001] Endoscope device, correction pair arrangement, endoscope and imaging system

[0002] The invention relates to an endoscope device, in particular for hyperspectral and / or multispectral imaging, a correction pair arrangement for a lens arrangement of an endoscope, an endoscope and an imaging system with an endoscope.

[0003] Lens arrangements for endoscopes that feature multiple rod lenses are known from the prior art. Such lens arrangements are combined with an objective lens and an eyepiece. Light entering the objective lens from an observed object can be transmitted through the lens arrangement to the eyepiece. This allows the observed object to be imaged in a known manner.

[0004] In the field of endoscopy, endoscopic devices that produce multispectral or hyperspectral images are increasingly being used. In addition to two spatial dimensions, such as a conventional camera image, multispectral or hyperspectral images also have a spectral dimension. The spectral dimension encompasses several spectral bands (wavelength bands). Multispectral and hyperspectral images differ essentially in the number and width of their spectral bands. Such systems can, in principle, also be suitable for taking fluorescence images.

[0005] Some imaging devices for generating such multispectral or hyperspectral images, particularly in the context of medical applications, are known. DE 20 2014 010 558 U1, for example, describes a device for recording a hyperspectral image of an examination area of ​​a body. The device includes an input lens for generating an image in an image plane and a slit-shaped aperture in the image plane for masking out a slit-shaped region of the image. The light passing through the aperture is spread out by a dispersive element and recorded by a camera sensor. As a result, the camera sensor can record a large number of spectra, each with an associated spatial coordinate along the longitudinal direction of the slit-shaped aperture.The described device is further configured to record additional spectra along the longitudinal direction of the slit-shaped aperture in a direction different from the longitudinal direction of the slit-shaped aperture. The method underlying this disclosure for generating multispectral or hyperspectral images is also known as the so-called pushbroom method.

[0006] In addition to the pushbroom method, there are other techniques for generating multispectral or hyperspectral images. In the so-called whiskbroom method, the area under investigation or object is scanned point by point, and a spectrum is obtained for each point. In contrast, the staring method involves taking multiple images with the same spatial coordinates. Different spectral filters and / or illumination sources are used from image to image to resolve spectral information. There are also methods according to which a two-dimensional multi-color image is broken down into multiple individual spectral images using suitable optical elements such as optical slicers, lenses, and prisms. These individual spectral images are then acquired simultaneously on different detectors or detector areas. This is sometimes referred to as the snapshot approach.

[0007] As described in DE 10 2020 105 458 A1, multispectral and hyperspectral imaging devices are particularly suitable as endoscopic imaging devices. In this context, multispectral and / or hyperspectral imaging is a fundamental field of application, for example, for diagnostics and for assessing the success or quality of an intervention.

[0008] Multimodal endoscope devices allow the acquisition of white light images and / or multispectral images and / or fluorescence images and / or hyperspectral images.

[0009] For the applications mentioned, it is advantageous or even essential to be able to transmit and image light in both the visible and near-infrared range. Multispectral or hyperspectral imaging, for example, is particularly versatile when it is possible to work in a spectral range between approximately 450 nm and 1000 nm. For fluorescence imaging, it is also advantageous if a broad spectral range is available because the same optical system can then be used to acquire fluorescence images and white light images. The latter often provide more comprehensive information about the anatomy under consideration, which is why it is advisable to combine them with fluorescence images. In this regard, existing lens arrangements deliver an imaging quality that is often not satisfactory across a broad spectral range.It is then regularly necessary to work with reduced resolution or inadequate focusing in parts of the total spectral range used.

[0010] In addition, it is often unsatisfactory for users to work with a focus optimized for the near-infrared range if this is accompanied by defocusing in the visible range, because the image quality is then subjectively perceived as inadequate.

[0011] In practice, it is often impractical for users to adjust the focus of the endoscope device used depending on the respective observation mode. If overlay images are to be created, for example by superimposing white light images and fluorescence images or white light images and hyperspectral images / multispectral images, switching may be automated and carried out at very short time intervals. Fluorescence imaging and multispectral imaging can be carried out in real time. Hyperspectral imaging is regularly carried out at least essentially in real time; the acquisition of a hyperspectral image dataset, for example, takes a few seconds. However, all wavelengths are observed in a single image acquisition, which is why wavelength-dependent adjustment of the focus is not practical.Based on the state of the art , the invention is based on the object of enabling endoscopic images of high quality in a broad spectral range .

[0012] This object is achieved according to the invention by an endoscope device, a correction pair arrangement for a lens arrangement of an endoscope, an endoscope and an imaging system as described herein and defined in the claims.

[0013] An endoscope device, in particular for hyperspectral and / or multispectral imaging, comprises a lens arrangement which defines an optical axis and which is configured to optically couple an eyepiece to an objective lens. The lens arrangement is configured, in particular for a given focus, for at least substantially equivalent transmission and / or imaging of light both in the visible range and in the near-infrared range, and in particular both over a large part of the visible range and in the near-infrared range. The lens arrangement is symmetrical with respect to a first plane of symmetry which is perpendicular to the optical axis.

[0014] The lens arrangement comprises at least six rod lenses and at least two corrective elements which, together with the rod lenses, define an optical system and which each comprise a lens system with at least a first lens and a second lens. The first lens is made from a first glass and the second lens is made from a second glass. The first glass and the second glass have different Abbe numbers. A relative partial dispersion of the first glass and a relative partial dispersion of the second glass deviate in opposite ways from glass with normal dispersion. Furthermore, the lens arrangement comprises at least one corrective pair arrangement which comprises two of the corrective elements which are symmetrical to one another with respect to a second plane of symmetry which is perpendicular to the optical axis.The invention additionally relates to a correction pair arrangement for a lens arrangement of an endoscope, comprising at least two correction elements which define an optical axis and which are designed to define an optical system together with a plurality of rod lenses and which each comprise a lens system with at least a first lens and a second lens. The first lens is made of a first glass and the second lens is made of a second glass. The first glass and the second glass have different Abbe numbers. A relative partial dispersion of the first glass and a relative partial dispersion of the second glass deviate in opposite ways from glass with normal dispersion. The correction elements are symmetrical to one another with respect to a plane of symmetry which is perpendicular to the optical axis.

[0015] The features according to the invention enable endoscopic images with high quality across a broad spectral range. The inventors have recognized that in order to achieve high image quality across a broad spectral range, lens errors must be addressed in a very targeted manner and that, for this purpose, optical components must be suitably selected and combined. By using paired correction elements and the use of suitable symmetry in the design of the lens arrangement, chromatic aberration can be advantageously reduced such that images with high image quality can be recorded both in the visible range and in the near-infrared range, without the focus having to be adjusted / set depending on the wavelength.Furthermore, the inventors have recognized that, particularly for high-quality multispectral or hyperspectral imaging, the highest possible light intensities should be present on the corresponding detection sensors, if possible across the entire imaged spectral range. Furthermore, the use of rod lenses and additional correction elements makes it possible to use conventional assembly methods for the manufacture of endoscopes or endoscope shafts in which endoscope devices or lens arrangements according to the invention are used. Known process steps can be used to construct the lens system; only the combined optical components differ from previous lens arrangements.

[0016] The objective may comprise a lens system configured to allow the coupling of light and to transmit coupled light to the lens arrangement. The coupled light is, for example, light that has been remitted and / or emitted by an object to be observed. In particular, it may be remitted illumination light and / or fluorescent light.

[0017] In some embodiments, the eyepiece is configured to feed light transmitted by the lens arrangement to an image acquisition sensor. The image acquisition sensor can be part of an imaging unit, in particular a multimodal imaging unit, by means of which multispectral imaging, hyperspectral imaging, white-light imaging, and / or fluorescence imaging can be carried out, preferably selectively.

[0018] The endoscope device can be a component of an endoscope, in particular a medical endoscope. In general, it can be a medical endoscope device. In addition to the endoscope device, the endoscope can comprise the eyepiece and / or the objective. Alternatively or additionally, the eyepiece and / or the objective can be part of the endoscope device.

[0019] Multispectral imaging can refer in particular to imaging in which at least two, in particular at least three, and in some cases at least five spectral bands are and / or can be detected independently of one another. The individual spectral bands for the multispectral imaging can be defined by suitable and, if appropriate, switchable optical filters. Hyperspectral imaging can refer in particular to imaging in which at least 20, at least 50 or even at least 100 spectral bands are and / or can be detected independently of one another. Hyperspectral imaging can, for example, be carried out using the pushbroom method and / or the whiskbroom method and / or the staring method and / or a snapshot principle.

[0020] The rod lenses can, in particular, be arranged such that their longitudinal axes are parallel to one another and / or parallel to the optical axis of the lens arrangement. Preferably, the longitudinal axes of the rod lenses and the optical axis coincide. The rod lenses and the correction elements can be arranged such that light that is transmitted and / or imaged by the lens arrangement passes through all rod lenses and all correction elements.

[0021] In some embodiments, the lens arrangement may have a length of at least 20 cm, at least 30 cm, or even at least 40 cm. The lens arrangement may be rigid. In other words, components of the lens arrangement, for example, the at least six rod lenses and the at least two correction elements, in particular all components of the lens arrangement, may be immobile relative to one another.

[0022] The endoscope device may further comprise the eyepiece and / or the objective lens. The eyepiece and / or the objective lens, together with the lens arrangement, may form an imaging optical system.

[0023] The endoscope device may comprise a shaft in which the lens arrangement is received and / or secured. In this case, the optical axis may be arranged parallel to a longitudinal axis of the shaft and, in particular, may coincide with it. In other words, the shaft, the rod lenses, and, in particular, the correction elements may be arranged coaxially.

[0024] By "a large part of a wavelength range" is meant in particular a preferably contiguous wavelength range which covers at least 60%, preferably at least 70%, particularly preferably at least 80% and preferably at least 90% of the reference wavelength range. The visible wavelength range can in particular be understood to mean the range from 400 nm to 750 nm. The term "near-infrared range" in this context relates in particular to wavelengths which lie outside the visible wavelength range. In particular, the lens arrangement can be set up for at least essentially equivalent transmission and imaging of light for a given focus both over the large part of the visible range and over a large part of at least the range from 800 nm to 1000 nm.In other words, the lens arrangement can be arranged for at least substantially equivalent transmission and imaging of light for a given focus over a large part of the range from 480 nm to 900 nm and preferably over a large part of the range from 400 nm to 1000 nm.

[0025] An “at least substantially equivalent transmission of light” is to be understood in particular as meaning that an average transmission in the said wavelength range for all pairs of arbitrarily selectable intervals in the said wavelength range, which have a width of at most 100 nm, at most 50 nm or even at most 10 nm, differs between the intervals by at most 30%, preferably by at most 20%, particularly preferably by at most 15% and preferably by at most 10%. An “at least substantially equivalent transmission of light” can comprise that a transmission in the said wavelength range for all pairs of arbitrarily selectable wavelengths in the said wavelength range differs between the wavelengths by at most 30%, preferably by at most 20%, particularly preferably by at most 15% and preferably by at most 10%."Transmission" refers in particular to a degree of transmission, i.e. a quotient of transmitted and incident intensity. The information refers in particular to those light intensities for which the transmission shows no or at least essentially no intensity dependence.

[0026] An "at least substantially equivalent transmission and imaging of light" refers in particular to the lens arrangement being usable over a large part of the visible range as well as in the near-infrared range. In other words, the lens arrangement is usable, in particular equally usable, in both the visible range and the near-infrared range for a given focus.

[0027] A "substantially equivalent transmission of light" can be understood specifically as meaning that an average transmission in the said wavelength range for all pairs of arbitrarily selectable intervals in the said wavelength range, which have a width of at most 100 nm, at most 50 nm or even at most 10 nm and in which in particular the average transmission is less than 95%, less than 90% or less than 85%, differs between the intervals by at most 30%, preferably by at most 20%, particularly preferably by at most 15% and preferably by at most 10%.An "at least substantially equivalent transmission of light" can comprise that a transmission in the stated wavelength range for all pairs of arbitrarily selectable wavelengths in the stated wavelength range, where in particular the transmission is less than 95%, less than 90% or less than 85%, differs between the wavelengths by at most 40%, preferably by at most 30%, particularly preferably by at most 20% and preferably by at most 10%. In addition, the term can include that at least a sub-range of the stated wavelength range exists in which the transmission is greater than 80%, greater than 85% or even greater than 90%. "Transmission" here means in particular a degree of transmission, i.e. a quotient of transmitted and incident intensity.The data refer in particular to light intensities for which the transmission shows no, or at least essentially no, intensity dependence. In other words, the transmission of light across the entire wavelength range mentioned is possible with sufficient efficiency.

[0028] A "substantially equivalent imaging of light" can be understood specifically to mean that in the stated wavelength range, for all pairs of arbitrarily selectable intervals in the stated wavelength range which have a width of at most 100 nm, at most 50 nm or even at most 10 nm and in which in particular an average RMS point radius ("RMS" stands for "root mean square") lies above the diffraction limit, an average RMS point radius between the intervals differs by at most a factor of 15, preferably by at most a factor of 10, particularly preferably by at most a factor of 5 and preferably by at most a factor of 3.A "substantially equivalent imaging of light" can comprise that an RMS spot radius for all pairs of arbitrarily selectable wavelengths in the stated wavelength range, in which in particular the RMS spot radius lies above the diffraction limit, differs between the wavelengths by a factor of 15 at most, preferably by a factor of 10 at most, particularly preferably by a factor of 5 at most and preferably by a factor of 3 at most. In addition, the term can include that at least a sub-range of the stated wavelength range exists in which the RMS spot radius lies below the diffraction limit. In other words, the imaging of light over the entire stated wavelength range is possible with sufficiently high focusing.

[0029] The term "for a given focus" means in particular that the incidence of light into the lens arrangement is unchanged, i.e. it occurs in the same way for different wavelengths. If, for example, the lens arrangement is combined with an objective and / or eyepiece and is focused, the focus for assessing the transmission and imaging of the light at different wavelengths does not change. The focus can comprise a predetermined and / or predeterminable focus for a specific wavelength in the stated wavelength range, which focus is then maintained unchanged over the entire stated range.

[0030] The rod lenses and / or the correction elements can be designed as at least substantially cylindrical, preferably circular-cylindrical, objects. A lateral surface of the rod lenses and / or the correction elements can be cylindrical. Front and / or rear surfaces of the rod lenses and / or the correction elements can deviate from the shape of a cylinder and, for example, be convexly or concavely curved.

[0031] The rod lenses are preferably elongated. The rod lenses can, for example, have a length that is at least a factor of 2, a factor of 3, a factor of 4, a factor of 5, or even a factor of 6 greater than the diameter of the rod lenses. The rod lenses can be configured differently or identically. In some embodiments, the lens arrangement can comprise several different rod lens types. These can differ in terms of their dimensions, curvature, refractive behavior, coating, material, and / or other parameters.

[0032] The term "glass" may refer to any glass material in this disclosure. "Glass" is not intended to be limited to silicate glass or silicon-based glass, although in some embodiments the first glass and / or the second glass may be silicate glass or silicon-based glass, respectively.

[0033] The Abbe number can be defined in the context of this disclosure as

[0034] Vd = (n d - 1 ) / (n F - n c ) , where n , n F and nc are the refractive indices of the material in question at the corresponding Fraunhofer lines. For example, the corresponding wavelengths for the Fraunhofer lines d, F, and C are 587.56 nm, 486.13 nm, and 656.27 nm.

[0035] Alternatively, the Abbe number may also be defined in this disclosure as

[0036] Ve = (n e - 1 ) / (n F ' - n C ') , where n e , n F > and nc' are the refractive indices of the material in question at the corresponding Fraunhofer lines. For example, the corresponding wavelengths for the Fraunhofer lines e, F', and C' are 546.07 nm, 479.99 nm, and 643.85 nm.

[0037] The relative partial dispersion mentioned can generally be the relative partial dispersion for two wavelengths x, y, which can be defined as follows:

[0038] Px,y = (n x - n y ) / (n F - n c ), where n x and n y denote the refractive indices at wavelengths x and y . In particular, the relative partial dispersion of the first glass and the second glass can be P g , F , where g and F denote the corresponding Fraunhofer lines. The corresponding wavelengths for the Fraunhofer lines g and F and C ' are, for example, 435.83 nm and 486.13 nm.

[0039] A glass with normal dispersion is to be understood in particular as a glass for which the relative partial dispersion and the Abbe number are linearly related, i.e. in particular glass which lies on a straight line in a Vd-P x , y - diagram which obeys the following relation :

[0040] P x , y = a x , y + b x , y • v d , where a x , y and b x , y are dimensionless constants belonging to the partial dispersion determined by x and y . Analogously, this can also be said for v e be formulated. For P g , F These constants are known to be g , F = 0 , 6438 and b g , F= 0 , 001682 . Such glass is also regularly referred to as "normal glass". It is characterized by the fact that light is dispersed in the same way regardless of the spectral range.

[0041] By way of derogation from this, glass that deviates from glass with normal dispersion can display different dispersion behavior in different spectral ranges, for example, it can be more or less dispersive in the short-wave range than in the long-wave range. Such a glass is sometimes referred to as glass with abnormal dispersion. It should be understood that these terms are not to be equated with the sometimes used terms normal dispersion and anomalous dispersion, which refer to the fundamental dispersion behavior of a material, namely having a refractive index that increases with frequency ("normal dispersion") or that decreases with frequency ("anomalous dispersion"). Rather, the glass properties described herein may relate to different derivatives of the dispersion at different wavelengths, which may, however, have the same sign.

[0042] The relative partial dispersion of the first glass and the second glass differs in particular in the opposite way from glass with normal dispersion in that the first glass in the Vd-Px, y diagram is on one side of the line for glass with normal dispersion, and the second glass is on a second side opposite the first. This can be done analogously for a Vde-Px, y -diagram apply. A deviation parameter AP x , y be defined as follows:

[0043] AP x , y = (n x - n y ) / (n F - n c ) - a x , y + b x , y • .

[0044] Analogously, this can also be done for v e A sign of the value of the deviation parameter AP x , y may be different for the first glass and the second glass.

[0045] The first lens may consist at least to a large extent and / or entirely of the first glass. The second lens may consist at least to a large extent and / or entirely of the second glass. "At least a large part" may mean at least 55%, preferably at least 65%, more preferably at least 75%, more preferably at least 85%, and most preferably at least 95%, in particular with reference to a volume and / or a mass of an object.

[0046] Preferably, the first lens and the second lens are arranged directly one behind the other and in particular in contact with one another and / or are formed integrally with one another, for example optically bonded and / or adhesively bonded. The correction elements of the correction pair arrangement can be arranged symmetrically to one another with respect to the second plane of symmetry. The correction elements of the correction pair arrangement can be identical and, for example, merely rotated relative to one another to establish symmetry. In other embodiments, the correction elements can be formed differently but symmetrically to one another.

[0047] A simple optical design can be achieved, in particular, when the first plane of symmetry and the second plane of symmetry are identical. This makes optical modeling for adapting the lens arrangement particularly easy. In other embodiments, the first plane of symmetry and the second plane of symmetry can be spaced apart from one another along the optical axis.

[0048] In some embodiments, the lens arrangement comprises at least one further correction pair arrangement, wherein the further correction pair arrangement comprises two further correction elements that are symmetrical to one another with respect to a third plane of symmetry that is perpendicular to the optical axis. This makes it possible to achieve a high degree of imaging quality and imaging stability. The further correction pair arrangement can be designed identically to the correction pair arrangement. Alternatively, the correction pair arrangements can differ, for example with regard to the correction elements used and / or their relative position and / or orientation.

[0049] A high degree of flexibility with regard to the design of the lens arrangement and the associated diverse possibilities for achieving high imaging quality can be achieved in particular when the second plane of symmetry and the third plane of symmetry are different from the first plane of symmetry. The second plane of symmetry and the third plane of symmetry can be identical. Alternatively, it can be provided that the second plane of symmetry is different from the third plane of symmetry. The planes of symmetry can be spaced from one another along the optical axis. In further embodiments, the first plane of symmetry and the third plane of symmetry can be identical to one another but different from the second plane of symmetry.

[0050] In the context of this disclosure, different planes of symmetry can be spaced apart from one another along the optical axis by at least 1 cm, by at least 2 cm, by at least 5 cm, by at least 10 cm or even by at least 20 cm.

[0051] Furthermore, it can be provided that the correction elements each comprise at least a third lens. In some

[0052] In some embodiments, the third lens is made of the first glass and / or the second glass. In other

[0053] In some embodiments, the third lens can also be made from a third glass that is different from the first glass and / or the second glass. The third glass can in particular be different from a glass that shows normal dispersion within the meaning of this disclosure. The third lens can consist at least largely and / or completely of the first glass, the second glass or the third glass. The second lens can in this case be arranged between the first lens and the third lens. Preferably, the first lens, the second lens and the third lens are arranged directly one behind the other and in particular in contact with one another and / or are formed integrally with one another, for example optically bonded and / or adhesively bonded.

[0054] The assembly effort and / or the number of components can be reduced in particular if the correction elements are each formed integrally with a rod lens. Generally speaking, at least one of the correction elements can be formed integrally with at least one of the rod lenses. “Integral” here includes both integral and one-piece. At least one lens of the relevant correction element can be formed integrally with the relevant rod lens. Preferably, all lenses of the relevant correction element are formed integrally with the relevant rod lens. For example, in these cases the first lens can be arranged directly next to the rod lens and / or optically bonded and / or adhesively adhered to it. The arrangement can also be reversed, so that the second lens is arranged directly next to the rod lens.The second lens can then additionally be arranged directly adjacent to the first lens and / or optically bonded and / or glued thereto. In some embodiments, the corrective element can be attached to a planar surface of the rod lens and / or bonded and / or glued thereto.

[0055] Furthermore, the correction pair arrangement can comprise at least one aperture which is arranged in the region of the second plane of symmetry. In this way, an aperture of the lens arrangement can be expediently attached. In some variants, the second plane of symmetry intersects the aperture. The aperture has in particular a smaller diameter than the rod lenses and / or the correction elements and / or the lenses of the correction elements. Information regarding a symmetry of the lens arrangement can relate in particular to the components of the lens arrangement without the aperture, i.e. apart from the aperture. In other words, the lens arrangement without the aperture can be symmetrical, but the aperture can be arranged off-center, for example. In principle, a plurality of apertures can also be provided. These can be arranged symmetrically to one another with respect to one or any or all of the said planes of symmetry and / or each be designed symmetrically thereto.

[0056] Depending on the design of the lens arrangement or the optical system that defines the rod lenses and the correction elements, at least one of the first lenses and / or at least one of the second lenses can be a convex lens. Alternatively or additionally, at least one of the first lenses and / or at least one of the second lenses can be a concave lens. The second lenses can be identically designed. The first lenses can be identically designed.

[0057] A high image quality over a large spectral range can be achieved in particular when the lens arrangement in the range from 400 nm to 1000 nm enables optical images which have an RMS spot radius of at most 40 pm, preferably at most 35 pm and preferably at most 30 pm. This can mean in particular that for any arbitrarily selected interval in this range with a width of at most 50 nm, preferably at most 40 nm, particularly preferably at most 30 nm and preferably at most 20 nm, an average RMS spot radius is at most 40 pm, preferably at most 35 pm and preferably at most 30 μm. This can also mean that for any arbitrary wavelength an RMS spot radius is at most 40 μm, preferably at most 35 μm and preferably at most 30 μm.

[0058] In some embodiments, the lens arrangement can enable diffraction-limited optical imaging in the range from 480 nm to 1000 nm. In other words, the lens arrangement can be configured such that a diffraction-limited optical imaging is enabled for any wavelength in the range from 480 nm to 1000 nm. A diffraction-limited optical imaging is characterized in particular by a calculated RMS spot radius being less than or equal to a value defined by the diffraction limit.

[0059] The lens arrangement can have a maximum RMS spot radius of at most 8 pm, preferably at most 6 pm, and preferably at most 4 pm, in particular in the range from 480 nm to 1000 nm. In other words, for any wavelength, in particular in the range from 480 nm to 1000 nm, an RMS spot radius can have at most 8 pm, preferably at most 6 pm, and preferably at most 4 pm.

[0060] The inventors have further recognized that, while conventional lens arrangements sometimes transmit well in the visible range, they exhibit significantly poorer transmission in the near-infrared range. This significantly limits the usability of such conventional lens arrangements, particularly for multispectral and hyperspectral applications, which also require imaging in the near-infrared range. High-quality imaging in a broad spectral range can be achieved, in particular, if the rod lenses and the correction elements have anti-reflective surfaces that are effective in the visible and near-infrared ranges.In other words, the anti-reflective surfaces can be designed in such a way that, in contrast to anti-reflective surfaces that only optimize transmission in the visible range, a somewhat lower transmission may be accepted under certain circumstances, but in return the transmission remains at a high level beyond the visible range instead of decreasing rapidly. Anti-reflective surfaces can comprise a coating on the relevant optical elements, for example an anti-reflective coating. Alternatively or additionally, a surface of the relevant optical elements themselves can be treated, for example, microscopically and / or nanoscopically roughened.

[0061] In particular, it can be provided that the anti-reflective surfaces in the range from 400 nm to 1000 nm each have an average reflection of at most 2%, preferably of at most

[0062] 1% and preferably of at most 0.6%. Alternatively or additionally, it can be provided that the anti-reflective surfaces in the range from 400 nm to 1000 nm each have a maximum reflection of at most 3%, preferably of at most

[0063] 2% and preferably not more than 1%.

[0064] The anti-reflective surfaces mentioned can be present on at least one surface of at least one optical element of the lens arrangement, for example on at least one rod lens and / or on at least one correction element, for example on at least one of the lenses. Preferably, at least a majority of the existing surfaces are provided with anti-reflective surfaces, preferably all of them.

[0065] The lens arrangement can have an average transmission of at least 70%, preferably at least 80% and particularly preferably at least 85% in the range from 400 nm to 1000 nm. Alternatively or additionally, the lens arrangement can have a minimum transmission of at least 60%, preferably at least 70% and particularly preferably at least 80% in the range from 400 nm to 1000 nm. This makes it possible to transmit light across a broad spectrum through the entire lens arrangement, as a result of which light can be transmitted efficiently both in the visible range and in the near-infrared range. The invention further relates to an endoscope with an endoscope device according to the invention and / or with a correction pair arrangement according to the invention.In some embodiments, the endoscope is configured to be insertable into a cavity for inspection and / or observation, for example into an artificial and / or natural cavity, such as into the interior of a body, into a body organ, into tissue, or the like. The endoscope can also be configured to be insertable into a housing, casing, shaft, pipe, or other, particularly artificial, structure for inspection and / or observation.

[0066] Furthermore, the invention relates to an imaging system, in particular a medical imaging system. The imaging system comprises an illumination device which is configured to provide illumination light both in the visible range and in the near-infrared range. Furthermore, the imaging system comprises an endoscope device according to the invention and / or an endoscope according to the invention. In addition, the imaging system comprises an imaging device with an image acquisition unit which is configured to acquire multispectral and / or hyperspectral image data. The image acquisition unit can comprise an image acquisition sensor system.

[0067] The imaging system may be multimodal. In particular, the imaging system may be configured to selectively acquire white-light images and / or multispectral images and / or fluorescence images and / or hyperspectral images.

[0068] The image capture sensor system can be configured to detect light in both the visible range and the near-infrared range. In some embodiments, a smallest detectable wavelength can be at most 500 nm, at most 450 nm, or even at most 400 nm. In some embodiments, a largest detectable wavelength can be at least 800 nm, at least 900 nm, or even at least 1000 nm. The image capture sensor system can, for example, comprise at least one white-light image sensor and at least one near-infrared image sensor. In some embodiments, the imaging device comprises a white-light camera and / or sensors for white-light image capture. The imaging device can be configured for white-light imaging. The anatomical images can be recorded using the white-light camera and / or the sensors for white-light image capture.

[0069] The image acquisition unit can have a filter unit with optical observation filters. The filter unit can define multiple fluorescence modes defined by different observation filters. For example, different edge filters can be used that absorb / block the respective spectrum of the associated light element used for excitation and at least essentially transmit only fluorescent light. The observation filter, which blocks light in the first spectral range, is then part of the filter unit. In some embodiments, the observation filters can also be switchable between a multispectral mode and a fluorescence mode.

[0070] The imaging device and in particular an optical system and / or the image capture sensor system can be configured for multispectral and / or hyperspectral imaging, in particular for capturing and / or generating multispectral and / or hyperspectral image data. Multispectral imaging or multispectral image data can in particular refer to imaging in which at least two, in particular at least three, and in some cases at least five spectral bands can be and / or are captured independently of one another. Hyperspectral imaging or hyperspectral image data can in particular refer to imaging in which at least 20, at least 50 or even at least 100 spectral bands can be and / or are captured independently of one another.The imaging device may operate according to the pushbroom method and / or the whiskbroom method and / or the staring method and / or a snapshot principle.

[0071] For some applications it can be advantageous to be able to use a high spectral resolution . In this case hyperspectral imaging is a good option . This can be combined with white light imaging . This enables real-time observation via a white light image, even if the acquisition of spectrally resolved image data only takes place essentially in real time, i.e. several seconds are needed to create a spectrally resolved image . For some applications it can be advantageous to generate spectral image data in real time . This includes, for example, generating a spectrally resolved image in less than a second or even several times per second . In this case it can be useful to use multispectral imaging . A possibly lower spectral resolution is then offset by a higher frame rate .Depending on the application, it may be sufficient to consider only a few different spectral ranges and / or wavelengths, for example, two, three, or four, or generally fewer than ten. In this case, additional white-light imaging can optionally be omitted. Spectrally resolved image data acquired in real time or delivering multiple images per second can also be used for surveillance purposes. It is not necessary to create an image for display by a user; the image data can also be processed in the background.

[0072] The image capture sensor system has, in particular, at least one image sensor. Furthermore, the image capture sensor system can also have at least two and preferably more image sensors, which can be arranged one behind the other. Furthermore, the two and preferably more image capture sensors can have spectral capture sensitivities that differ from one another, so that, for example, a first sensor is particularly sensitive in a red spectral range, a second sensor in a blue spectral range, and a third sensor in a green spectral range or is comparatively more sensitive than the other sensors. The image sensor can be designed, for example, as a CCD sensor and / or a CMOS sensor. The image capture unit is, in particular, configured to generate at least two-dimensional spatial image data.The image acquisition unit can be spatially resolving in such a way that it provides a resolution of at least 100 pixels, preferably of at least 200 pixels, more preferably of at least 300 pixels and advantageously of at least 400 pixels in at least two different spatial directions. The image data is preferably at least three-dimensional, with at least two dimensions being spatial dimensions and / or with at least one dimension being a spectral dimension. A plurality of spatially resolved images of the image area can be obtained from the image data, each of which is assigned to different spectral bands. The spatial and spectral information of the image data can be such that an associated spectrum can be obtained therefrom for a plurality of spatial pixels.

[0073] In some embodiments, the image acquisition unit is configured to generate continuously updated image data. The image acquisition unit can, for example, be configured to generate the image data substantially in real time, which includes, for example, generating updated image data at least every 30 seconds, in some cases at least every 20 seconds, and in some cases even at least every 10 seconds or at least every 5 seconds. Preferably, the image acquisition unit is configured to generate at least the anatomical images and the fluorescence images, as well as the representation based thereon, in real time, for example at a frame rate of at least 5 fps, at least 10 fps, at least 20 fps, or even at least 30 fps.

[0074] The lighting device can be multimodal and comprise a plurality of independently selectably activatable lighting elements which are configured to emit light according to different emission spectra in order to provide the illumination light.

[0075] The lighting device can comprise an optical interface for optically connecting the endoscope. The lighting unit can be configured to supply illumination light to the optical interface. The lighting unit can be multimodal and comprise a plurality of independently selectable activatable lighting elements which are configured to emit light according to different emission spectra in order to supply the illumination light. The lighting unit can be operable in at least one multispectral mode in which a first group of the lighting elements is at least temporarily activated and in which the lighting unit supplies illumination light for multispectral imaging.Furthermore, the illumination unit can be operable in at least one fluorescence mode, in which a second group of the luminous elements is at least temporarily activated and in which the illumination unit provides illumination light for fluorescence imaging. The luminous elements can comprise at least one luminous element that is contained in both the first group and the second group.

[0076] In addition, a method for generating illumination light for an imaging device by means of an illumination device can be provided. The illumination device comprises an optical interface for optically connecting the endoscope and an illumination unit which is designed to supply illumination light to the optical interface, wherein the illumination unit comprises a plurality of independently selectably activatable illumination elements which are designed to emit light according to different emission spectra in order to supply the illumination light. The method comprises the step of at least temporarily activating a first group of the illumination elements in order to supply illumination light for multispectral imaging and the step of at least temporarily activating a second group of the illumination elements in order to supply illumination light for fluorescence imaging.At least one of the light elements is activated at least temporarily both when the first group of light elements is activated at least temporarily and when the second group of light elements is activated at least temporarily. The optical interface can be optionally connectable and detachable. Furthermore, the optical interface can be combined with a mechanical interface, so that an optical connection is automatically established, for example, when the endoscope is mechanically coupled.

[0077] The lighting elements can comprise single-color LEDs (light-emitting diodes) and / or laser diodes. Furthermore, at least one of the lighting elements can be a white light LED or another white light source. In some embodiments, the lighting unit comprises at least one blue lighting element, at least one red lighting element, at least one far-red lighting element, and at least one near-IR lighting element (near-infrared lighting element), in particular LEDs or laser diodes. In addition, the lighting unit can comprise at least one white light LED or another white light source.

[0078] The first group can comprise at least two light-emitting elements which emit spectrally differently. A high degree of efficiency in multispectral imaging can be achieved if the multispectral mode comprises different states in each of which a specific light-emitting element or a specific type of light-emitting element is activated at least temporarily. This allows targeted illumination in a specific spectral range, whereby different spectral images can be captured. Different light-emitting elements which are activated in different states can serve as different support points for the multispectral imaging. At least one of these support points can be selected such that it is adapted to characteristic points of absorption spectra of physiologically relevant components, for example to an isosbestic point on the hemoglobin oxygenation curve.Multispectral imaging may additionally include the use of appropriate observation filters.

[0079] Furthermore, the second group can comprise at least two light-emitting elements which emit spectrally differently. The fluorescence mode can comprise different sub-modes and / or states, in each of which a specific light-emitting element or a specific type of light-emitting element is activated at least temporarily. This allows targeted excitation in a specific spectral range, so that fluorescence imaging can take place, for example, for a specifically selected dye. In other words, the at least one light-emitting element which is contained in both the first group and the second group can be used for both the multispectral mode and the fluorescence mode.

[0080] In some embodiments, the first group comprises only some but not all of the luminous elements. Alternatively or additionally, in some embodiments, the second group comprises only some but not all of the luminous elements. In the multispectral mode, in particular, only luminous elements of the first group are activated at least temporarily, whereas luminous elements that do not belong to the first group are deactivated. In the fluorescence mode, in particular, only luminous elements of the second group are activated at least temporarily, whereas luminous elements that do not belong to the second group are deactivated. In general, it is understood that the luminous elements can comprise different luminous element types and that, in particular, exactly one luminous element of each of the different luminous element types can be present.It is understood that mixed operating modes can also occur according to the invention, in which the aforementioned modes are used sequentially. For example, multispectral imaging and fluorescence imaging can be performed sequentially.

[0081] Synergy with regard to the use of a luminous element for different modes and associated efficiency gains can be achieved in particular if at least one luminous element which is contained in both the first group and the second group emits light in the red spectral range, in particular in a spectral range between 600 nm and 680 nm, for example between 610 nm and 650 nm or between 620 and 660 nm or between 630 and 670 nm. The spectral range can be narrowband and include the wavelength 660 nm. "Narrowband" can include a spectral width of at most 80 nm, in particular of at most 40 nm or even of at most 20 nm. This at least one luminous element can be configured to excite dyes absorbing in the red spectral range and to contribute to the illumination in the red spectral range for multispectral imaging.

[0082] In some embodiments, the illumination unit can be operable in at least one white light mode, in which the illumination unit supplies illumination light for white light imaging. The illumination light for white light imaging can be broadband white light. Alternatively, the illumination light for white light imaging can comprise several narrow wavelength bands that are separated from one another, for example a blue, a red, and a far-red band. "Dark red" is to be understood in the sense of "longer wavelength than red" and refers to the spectral position, not the light intensity. The illumination light for white light imaging can be mixed from light from different light elements.

[0083] In the white light mode, a third group of light elements can be activated at least temporarily to supply the illumination light for the white light imaging. The light elements can comprise at least one light element that is contained in the first group and / or in the second group as well as in the third group. In some cases, the third group can comprise only some but not all of the light elements. In the white light mode, in particular only light elements of the third group are activated at least temporarily, whereas light elements that do not belong to the third group are deactivated. In other words, the illumination unit can comprise light elements that serve one, two or all three of the aforementioned illumination modes. This allows a plurality of light elements to be used multiple times.

[0084] At least one luminous element contained in both the first group and / or the second group and the third group can emit light in the red spectral range, in particular in a spectral range between 600 nm and 680 nm, for example between 610 nm and 650 nm or between 620 and 660 nm or between 630 and 670 nm. The advantages of using luminous elements together are particularly evident when at least one red luminous element can be used for all three modes.

[0085] At least one luminous element contained in both the first group and / or the second group and the third group can emit light in the blue spectral range, in particular in a spectral range between 440 and 480 nm. At least one blue luminous element can expediently be used in both the fluorescence mode and the white light mode.

[0086] Generally speaking, the luminous elements can, as mentioned, comprise at least one, in particular blue, luminous element that emits light in a spectral range between 440 and 480 nm. In addition, the luminous elements can, as mentioned, comprise at least one, in particular red, luminous element that emits light in a spectral range between 600 and 680 nm, for example between 610 nm and 650 nm or between 620 and 660 nm or between 630 and 670 nm. Alternatively or additionally, the luminous elements can comprise at least one, in particular dark-red, luminous element that emits light in a spectral range between 750 and 790 nm. Alternatively or additionally, luminous elements can comprise at least one, in particular near-IR emitting, luminous element that emits light in a spectral range between 920 and 960 nm. In addition, the luminous elements can comprise a white light luminous element.A compact and versatile lighting unit can be provided in particular if at least one lighting element of each of the aforementioned lighting element types is present. For example, in fluorescence mode the blue and the red, and in the case of suitable dyes possibly also the dark red, lighting elements can be used. In multispectral mode the dark red and the near-IR emitting lighting element can be used. In white light mode the white light lighting element can be used. In white light mode this can be supplemented by the blue lighting element and possibly also the red lighting element. In this way, wavelength ranges can be supplemented by means of colored lighting elements in which the white light lighting element provides a reduced intensity, for example due to its design but in particular due to filters and optical elements of the lighting unit.In addition, the colored light elements can be used to set a color temperature for white light imaging.

[0087] In some embodiments, the second group comprises a single luminous element and / or a single type of luminous element. For example, a white light luminous element, a red luminous element, and an IR-emitting luminous element can be provided, with particular reference being made to the above values ​​with regard to possible spectral ranges. The first group can then, for example, comprise the red and the IR-emitting luminous element. The second group can comprise the IR-emitting luminous element, in particular as the only luminous element or as the only type of luminous element.

[0088] A favorable arrangement of lighting elements is made possible in particular if the lighting unit comprises at least one crossed beam splitter, by means of which light can be deflected from opposite input sides to an output side, with at least one of the lighting elements being arranged on each of the opposite input sides of the crossed beam splitter. In some embodiments, two or more crossed beam splitters can be provided, which are arranged optically one behind the other. The at least one crossed beam splitter can comprise two beam splitter elements, the transmittance of which is adapted to the respectively assigned lighting element. The beam splitter elements each comprise in particular a notch filter, so that they each reflect in a narrow spectral band, but otherwise transmit.The spectral position and / or width of the corresponding notch can be adapted to the spectral range of the respective associated luminous element, so that its light is deflected, but light from other luminous elements is at least largely transmitted.

[0089] In some embodiments, the luminous elements can comprise at least four narrow-band emitting single-color luminous elements, each with different spectral ranges, and at least one broadband emitting white-light luminous element. In this regard, reference is also made to the above explanations regarding the colored luminous elements.

[0090] A broad range of functions combined with a compact design and the exploitation of synergy effects when using lighting elements can be achieved, in particular, if the illumination unit is operable in at least one hyperspectral mode, in which several lighting elements are activated, whose emission spectra together cover at least a spectral range from 450 nm to 850 nm, and in which the illumination unit supplies illumination light for hyperspectral imaging. This can, in particular, involve all of the lighting elements.

[0091] It is understood that, particularly when using laser diodes, suitable polarization filters can be used for the optical filters mentioned herein. Furthermore, particularly when using laser diodes, at least one crossed beam splitter can be used, the beam splitter elements of which are provided with polarization filters. Selective transmission can then be achieved by combining different polarizations.

[0092] The devices and systems according to the invention, as well as the methods according to the invention, are not intended to be limited to the application and embodiment described above. In particular, to fulfill a function described herein, they may have a number of individual elements, components, units, and method steps that differs from the number stated herein. Furthermore, for the value ranges specified in this disclosure, values ​​within the stated limits are also intended to be disclosed and can be used arbitrarily.

[0093] It is particularly noted that all features and properties described with reference to a device, as well as procedures, are transferable to methods and can be used within the meaning of the invention and are considered to be co-disclosed. The same applies in the reverse direction. This means that structural features mentioned with reference to methods, i.e., features related to the device, can also be considered and claimed within the scope of the device claims and can also be counted as part of the disclosure.

[0094] The present invention is described below by way of example with reference to the accompanying figures. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will expediently consider the features individually and use them in meaningful combination within the scope of the claims.

[0095] If there is more than one example of a particular object, only one of them is provided with a reference symbol in the figures and in the description. The description of this example can be transferred accordingly to the other examples of the object. If objects are named in particular using numerical words, such as first, second, third object, etc., these serve to name and / or assign objects. Accordingly, a first object and a third object, but no second object, can be included. However, a number and / or a sequence of objects could also be derived from numerical words.

[0096] It shows :

[0097] Fig. 1 is a schematic representation of an imaging system with an illumination device, an endoscope with an endoscope device and an image acquisition device;

[0098] Fig. 2 is a schematic representation of a lens arrangement of an endoscope device according to the prior art;

[0099] Fig. 3 is a schematic representation of images of a line pattern produced with the lens arrangement according to the prior art; Fig. 4 is a diagram relating to the wavelength dependence of an RMS spot radius of the lens arrangement according to the prior art;

[0100] Fig. 5 is a schematic representation of a first endoscope device;

[0101] Fig. 6 is a schematic representation of a correction pair arrangement of the first endoscope device;

[0102] Fig. 7 is a diagram illustrating the selection of glass for the corrective pair arrangement;

[0103] Fig. 8 is a schematic representation of a second endoscope device;

[0104] Fig. 9 is a schematic representation of a correction pair arrangement of the second endoscope device

[0105] Fig. 10 is a schematic representation of a third endoscope device;

[0106] Fig. 11 is a schematic representation of a correction pair arrangement of the third endoscope device;

[0107] Fig. 12 is a schematic representation of images of a line pattern performed with the first endoscope device, the second endoscope device or the third endoscope device;

[0108] Fig. 13 is a diagram relating to the wavelength dependence of an RMS spot radius of the first endoscope device, the second endoscope device or the third endoscope device;

[0109] Fig. 14 is a schematic representation of a lens arrangement with anti-reflective surfaces;

[0110] Fig. 15 is a schematic diagram illustrating different reflectivity curves; Fig. 16 is a schematic diagram illustrating different transmission curves;

[0111] Fig. 17 is a schematic representation of the lighting device 150; and

[0112] Fig. 18 schematic transmission curves of beam splitter elements of the lighting device.

[0113] Fig. 1 shows a schematic representation of an imaging system 148. The imaging system 148 is an endoscopic imaging system. The imaging system 148 may be a medical imaging system. In the present case, the imaging system 148 is a multispectral and / or hyperspectral endoscopic imaging system.

[0114] The imaging system 148 includes an illumination device 150, an endoscope device 110, and an imaging device 152 with an image acquisition unit 154. The image acquisition unit 154 is configured to acquire multispectral and / or hyperspectral image data.

[0115] The image capture unit 154 comprises suitable image capture sensors 158, which are shown only as an example.

[0116] The image acquisition sensor 158 may comprise a CMOS or CCD sensor (not shown). The image acquisition sensor 158 and any associated optical elements may be arranged in a pushbroom arrangement. In other

[0117] In some embodiments, a whiskbroom arrangement, a staring arrangement, and / or a snapshot arrangement are used. Regarding different methods of hyperspectral imaging and the components required for this purpose, reference is made to the article "Review of spectral imaging technology in biomedical engineering: achievements and challenges" by Quingli Li et al., published in Journal of Biomedical Optics 18 (10), 100901, October 2013, and to the article "Medical hyperspectral imaging: a review" by Guolan Lu and Baowei Fei, published in Journal of Biomedical Optics 19 (1), 010901, January 2014.

[0118] In other embodiments, as mentioned, the image acquisition unit 154 can also be multispectral. Several spectral ranges can be viewed, for example, by filters that can be selectively inserted into an object light beam path and / or by sequential illumination with different wavelengths.

[0119] The endoscope device 110 is part of an endoscope 146. The endoscope 146 may include parts of the image capture unit 154. The endoscope device 110 includes a shaft 160. The shaft 160 is configured to receive a lens arrangement configured to guide imaging light from a distal end 162 of the endoscope device 110 and / or the shaft 160 to a proximal end 164 of the endoscope device 110 and / or the shaft 160. This will be discussed further below. The shaft 160 may be rigid. In particular, the endoscope 146 is a rigid endoscope and / or the endoscope device 110 is an endoscope device for a rigid endoscope.

[0120] Fig. 2 shows a schematic representation of a lens arrangement 212 of an endoscope device 210 according to the prior art. The endoscope device 212 comprises an eyepiece 216 and an objective 218. The lens arrangement 212 couples the eyepiece 216 and the objective 218 in a known manner. Light collected by the objective 218 can be transmitted through the lens arrangement 212 to the eyepiece 216. This can create an image.

[0121] The lens arrangement 212 comprises a plurality of rod lenses 222. The lens arrangement 212 is primarily intended to transmit and image light in the visible range, for example, in a range from 450 nm to 750 nm.

[0122] Fig. 3 shows a schematic representation of images of a line pattern, produced using the lens arrangement 212 according to the prior art. Fig. 4 shows a diagram relating to the wavelength dependence of an RMS spot radius of the lens arrangement 212. As can be seen, the RMS spot radius is small in a medium wavelength range and is even below the diffraction limit shown as a dashed line in Fig. 4. If the line pattern is imaged, the image shown in the middle of Fig. 3 is produced in the medium wavelength range, in this case for example for light with wavelengths between 486 nm and 656 nm. A sharp image of the line pattern can be obtained here because the lens arrangement 212 images well in this range. However, due to lens errors, in particular due to chromatic aberration, an equally sharp image cannot be obtained for smaller and larger wavelengths at the same time.In these ranges, the RMS spot radius is significantly larger, resulting in blurred images. This is illustrated in Fig. 3 on the left side for the wavelength range from 400 nm to 500 nm, and on the right side for the wavelength range from 800 nm to 1000 nm. Particularly in the near-infrared range, i.e., the latter range, the image quality is rather poor, meaning that geometric features cannot be imaged in detail.

[0123] The conventional endoscope device 210 is therefore primarily usable in the visible range. If it is used, for example, for white-light imaging, which roughly corresponds to a combination of the cases shown in Fig. 3 on the left and in the center, the image quality may be sufficient. However, if imaging is also required in the near-infrared range, the quality may not be sufficient to obtain meaningful image data that could be used, for example, to assess anatomical properties of a patient's anatomy being examined.

[0124] Fig. 5 shows a schematic representation of a first endoscope device 110 according to the present disclosure. The first endoscope device 110 can be used both in the visible range and in the near-infrared range. The endoscope device 110 comprises a lens arrangement 112, an eyepiece 116 and an objective 118. These are presently arranged in the shaft 160 shown in Fig. 1. The lens arrangement 112 optically couples the eyepiece 116 and the objective 118. Light can thus be transmitted and imaged essentially equally through the lens arrangement 112 at least in a range between 480 nm and 1000 nm, preferably in a range between 400 nm and 1000 nm.

[0125] The lens arrangement 112 comprises six rod lenses 122. The lens arrangement 112 further comprises two correction elements 124. The lens arrangement 112 defines an optical axis 114. The rod lenses 122 and the correction elements 124 are arranged coaxially with respect to the optical axis 114. In the illustrated case, the rod lenses 122 and the correction elements 124 each have a circular cross-section whose center lies on the optical axis 114.

[0126] The lens arrangement 112 is symmetrical with respect to a first plane of symmetry 120. The first plane of symmetry 120 is perpendicular to the optical axis 114.

[0127] The two correction elements 124 are part of a correction pair arrangement 134 or form it. The two correction elements 124 of the correction pair arrangement 134 are symmetrical to one another with respect to a second plane of symmetry 136. In this embodiment, the second plane of symmetry 136 corresponds to the first plane of symmetry.

[0128] The correction pair arrangement 134 is shown in more detail in Fig. 6. Each of the correction elements 124 of the correction pair arrangement 134 comprises a first lens 130, a second lens 132, and a third lens 142. These form a lens triplet. The first lens 130, the second lens 132, and the third lens 142 are integrally formed, for example, by adhesive bonding and / or optical bonding. Together, they form a lens system 128.

[0129] The first lens 130 is made of a first glass and the second lens 132 is formed of a second glass. The first glass and the second glass are selected such that they deviate in opposite ways from normal dispersion glass. This is schematically illustrated in Fig. 7. Fig. 7 shows a diagram in which the relative partial dispersion P g,F is plotted against the Abbe number d. The solid line defines the points at which glass with normal dispersion lies. In this regard, particular reference is made to the above comments on glass with normal and abnormal dispersion. The first glass and the second glass are located in the diagram at positions represented by the two black dots in Fig. 7. The first glass lies to the right of the line at a large Abbe number and deviates in a first direction from glass with normal dispersion. The second glass lies to the left of the line at a small Abbe number and deviates in a second direction, opposite to the first direction, from glass with normal dispersion.

[0130] The first glass, for example, has an Abbe number d of 63.66, a refractive index m of 1.61800, and a dispersion nF - nc of 0.009758. The second glass, for example, has an Abbe number Vd of 42.41, a refractive index m of 1.63775, and a dispersion nF - nc of 0.015038. The two glasses are therefore deliberately chosen to be different and deliberately designed such that their deviation from normal dispersion is opposite. This enables the lens arrangement 112 to deliver high-quality images over a broad spectral range.

[0131] In the present embodiment, the third lens 142 is also made of the first glass.

[0132] The first lens 130 is a concave lens. The second lens 132 is a convex lens. The third lens 142 is a concave lens. For example, the first lens 130 has a radius of curvature of -6 mm. Furthermore, the second lens 132 has a radius of curvature of 6 mm. Furthermore, the third lens 142 has a radius of curvature of 90 mm.

[0133] The correction pair arrangement 134 has an aperture 144 arranged in the region of the second plane of symmetry 136. The aperture 144 has a smaller diameter than the rod lenses 112 and the correction elements 124. Fig. 8 shows a schematic representation of a second endoscope device 110' according to the present disclosure. For better differentiation, the reference numerals of this embodiment are provided with inverted commas. Unless otherwise described, reference can generally also be made to the above explanations with regard to the components present. The second endoscope device 110' can be used both in the visible range and in the near-infrared range. The second endoscope device 110'' comprises a lens arrangement 112', an eyepiece 116' and an objective 118'. These are arranged in the shaft 160 shown in Fig. 1. The lens assembly 112' optically couples the eyepiece 116' and the objective 118'.Light can thus be transmitted and imaged essentially equally through the lens arrangement 112' at least in a range between 480 nm and 1000 nm, preferably in a range between 400 nm and 1000 nm.

[0134] The lens arrangement 112' comprises ten rod lenses 122'. Furthermore, the lens arrangement 112' comprises six correction elements 124'. The lens arrangement 112' defines an optical axis 114'. The rod lenses 122' and the correction elements 124' are arranged coaxially with respect to the optical axis 114'. In the illustrated case, the rod lenses 122' and the correction elements 124' each have a circular cross-section whose center lies on the optical axis 114'.

[0135] The lens arrangement 112' is symmetrical with respect to a first plane of symmetry 120'. The first plane of symmetry 120' is perpendicular to the optical axis 114'.

[0136] Two of the correction elements 124' are part of a correction pair arrangement 134' or form it. The two correction elements 124' of the correction pair arrangement 134' are symmetrical to each other with respect to a second plane of symmetry 136'. In this embodiment, the second plane of symmetry 136' corresponds to the first plane of symmetry.

[0137] Two further correction elements 124' each form two further correction pair arrangements 138', 168'. These are each symmetrical to each other with respect to a third symmetry plane 140' and a fourth symmetry plane 166', respectively. The third symmetry plane 140' and the fourth symmetry plane 166' are each perpendicular to the optical axis 114'.

[0138] The two further correction pair arrangements 138'', 168'' are arranged and / or formed symmetrically with respect to the first plane of symmetry 120''. Furthermore, as mentioned, the correction pair arrangement 134'' is symmetrical with respect to the first plane of symmetry 120''. The six correction elements 124'' are thus arranged symmetrically with respect to the first plane of symmetry 120'' in this embodiment.

[0139] The correction pair arrangement 134' is shown in more detail in Fig. 9. Each of the correction elements 124' of the correction pair arrangement 134' comprises a first lens 130' and a second lens 132'. The first lens 130' and the second lens 132' are integrally formed, for example, by adhesive bonding and / or optical bonding. Together, they form a lens system 128'.

[0140] The first lens 130' is made of a first glass, and the second lens 132' is formed of a second glass. The first glass and the second glass are selected such that they deviate from normal dispersion glass in opposite ways. For illustration, reference is again made to Fig. 7.

[0141] The first glass, for example, has an Abbe number d of 42.41, a refractive index m of 1.63775, and a dispersion nF - nc of 0.015038. The second glass, for example, has an Abbe number V of 63.33, a refractive index m of 1.61800, and a dispersion nF - nc of 0.009758. The two glasses are thus deliberately chosen to be different and deliberately designed so that their deviation from normal dispersion is opposite. This allows the lens arrangement 112' to deliver high-quality images over a wide spectral range.

[0142] The first lens 130' is a convex lens. The second lens 132' is a concave lens. For example, the first lens 130' has a radius of curvature of 12 mm. Furthermore, the second lens 132' has a radius of curvature of -4.8 mm.

[0143] The correction pair arrangement 134' has an aperture 144' arranged in the region of the second symmetry plane 136'. The aperture 144' has a smaller diameter than the rod lenses 112 and the correction elements 124.

[0144] In the present embodiment, the correction elements 124' are each formed integrally with a rod lens 122'. They are, for example, glued and / or optically bonded to a, particularly planar, end surface of the respective rod lens 122'.

[0145] On a side opposite the respective correction element 124', a further lens 172' is arranged, which is part of the rod lens 122'. This lens is glued and / or optically bonded to a base body of the rod lens 122'. In the present case, the base body of the rod lens 122' is made of a glass that has an Abbe number Vd of 50.19 and a refractive index m of 1.62658. The base body of the rod lens 122' has planar end surfaces. The further lens 172' is made of a glass that has an Abbe number Vd of 49.34, a refractive index m of 1.74320 and a dispersion nF - m of 0.015063. The further lens 172' is a concave lens and, for example, has a radius of curvature of 13.7 mm.

[0146] Fig. 10 shows a schematic representation of a third endoscope device 110'' according to the present disclosure. For better differentiation, the reference numerals of this embodiment are provided with two apostrophes. Unless otherwise described, reference can generally also be made to the above explanations with regard to the components present. The third endoscope device 110'' can be used both in the visible range and in the near-infrared range. The third endoscope device 110'' comprises a lens arrangement 112'', an eyepiece 116'' and an objective 118''. These are presently arranged in the shaft 160 shown in Fig. 1. The lens arrangement 112'' optically couples the eyepiece 116'' and the objective 118''.Light can thus be transmitted and imaged essentially equally through the lens arrangement 112'' at least in a range between 480 nm and 1000 nm, preferably in a range between 400 nm and 1000 nm.

[0147] The lens arrangement 112'' comprises six rod lenses 122''. Furthermore, the lens arrangement 112'' comprises four correction elements 124''. The lens arrangement 112'' defines an optical axis 114''. The rod lenses 122'' and the correction elements 124'' are arranged coaxially with respect to the optical axis 114''. In the illustrated case, the rod lenses 122'' and the correction elements 124'' each have a circular cross-section whose center lies on the optical axis 114''.

[0148] The lens arrangement 112'' is symmetrical with respect to a first plane of symmetry 120''. The first plane of symmetry 120'' is perpendicular to the optical axis 114''.

[0149] Two of the correction elements 124 ' ' are part of a correction pair arrangement 134 ' ' or form it. The two correction elements 124 ' ' of the correction pair arrangement 134 ' ' are symmetrical to one another with respect to a second plane of symmetry 136 ' '. The second plane of symmetry 136 ' ' is different from the first plane of symmetry 120 ' '. The second plane of symmetry 136 ' ' is perpendicular to the optical axis 114 ' '.

[0150] Two further correction elements 124 ' ' are part of a further correction pair arrangement 138 ' ' or form this. The two correction elements 124 ' ' of the further correction pair arrangement 138 ' ' are symmetrical to one another with respect to a third plane of symmetry 140 ' '. The third plane of symmetry 140 ' ' is different from the first plane of symmetry 120 ' ' and from the second plane of symmetry 136 ' '. The third plane of symmetry 140 ' ' is perpendicular to the optical axis 114 ' '.

[0151] The correction pair arrangement 134 ' ' and the further correction pair arrangement 138 ' ' are arranged and / or formed symmetrically with respect to the first plane of symmetry 120 ' '. In this embodiment, it can be provided that no correction pair arrangement is present in the region of the first plane of symmetry 120 ' '.

[0152] The correction pair arrangement 134'' is shown in more detail in Fig. 11. Each of the correction elements 124'' of the correction pair arrangement 134'' comprises a first lens 130'', a second lens 132'', and a third lens 142''. These form a lens triplet. The first lens 130'', the second lens 132'', and the third lens 142'' are integrally formed, for example, by gluing and / or optical bonding. Together, they form a lens system 128''.

[0153] The first lens 130" is made of a first glass, and the second lens 132 is formed of a second glass. The first glass and the second glass are selected such that they deviate from normal dispersion glass in opposite ways. For illustrative purposes, reference is again made to Fig. 7.

[0154] The first lens, for example, has an Abbe number d of 59.71, a refractive index m of 1.53996, and a dispersion nF - nc of 0.009120. The second lens, for example, has an Abbe number Vd of 63.33, a refractive index m of 1.61800, and a dispersion nF - nc of 0.009758. The two lenses are thus deliberately chosen to be different and deliberately arranged such that their deviations from normal dispersion are opposite. This allows the lens arrangement 112'' to deliver high-quality images over a wide spectral range.

[0155] In the present embodiment, the third lens 142" is made of a third glass different from the first glass and the second glass. The third glass has, for example, an Abbe number d of 47.11, a refractive index m of 1.67003, and a dispersion nF - nc of 0.014380.

[0156] The first lens 130'' is a convex lens. The second lens 132'' is a concave lens. The third lens 142'' is a convex lens. For example, the first lens 130'' has a radius of curvature of 8.5 mm. Furthermore, for example, the second lens 132'' has a radius of curvature of -7.8 mm. Furthermore, for example, the third lens 142'' has a radius of curvature of 82 mm.

[0157] The correction pair arrangement 134 '' has an aperture 144 '' arranged in the region of the second symmetry plane 136 ''. The aperture 144 '' has a smaller diameter than the rod lenses 112 '' and the correction elements 124 ''.

[0158] In the present case, no aperture is arranged in the region of the further correction pair arrangement 138'. In other embodiments, however, an aperture can be arranged in the region of the further correction pair arrangement 138' as an alternative or in addition to the aperture 144' of the first correction pair arrangement 134'.

[0159] Fig. 12 shows a schematic representation of images of a line pattern, carried out with the first endoscope device 110, the second endoscope device 110' or the third endoscope device 110". In contrast to the above-explained imaging of a line pattern with a lens arrangement according to the prior art, a comparatively sharp imaging of the line pattern is possible in the entire spectral range between 400 nm and 100 nm. The combination of the suitably selected glasses and the design and arrangement of the correction elements or correction pair arrangements allows high-quality imaging over a broad spectral range.

[0160] Fig. 13 shows a diagram relating to the wavelength dependence of an RMS spot radius of the first endoscope device 110, the second endoscope device 110' or the third endoscope device 110". The diffraction limit is shown as a dashed line. As can be seen, the RMS spot radius lies below the diffraction limit in at least one range between 480 nm and 1000 nm. At the blue edge of the range from 400 nm to 1000 nm, the RMS spot radius increases, but lies below 25 pm. This shows why the high-quality images of the line pattern shown in Fig. 12 are obtained for different spectral ranges.

[0161] Fig. 14 shows a schematic representation of a lens arrangement 112 with anti-reflective surfaces 170. Such anti-reflective surfaces 170 can be used in any of the embodiments described above. Fig. 15 shows a schematic diagram illustrating different reflectivity curves. The two dashed lines show conventional coatings that are optimized to operate in the visible range or just beyond. Although a low reflectivity can be achieved in the visible range, this is accompanied by a sudden increase in reflectivity in the red or near-infrared range. Such anti-reflective surfaces are only suitable to a limited extent for multispectral imaging, hyperspectral imaging, combined white light imaging and fluorescence imaging, or other imaging that requires imaging over a broad spectral range.

[0162] This is particularly evident in Fig. 16, which shows a schematic diagram illustrating different transmission curves. The transmission curves were calculated for a lens arrangement comprising, as an example, 30 surfaces. These are all provided with anti-reflective surfaces, which show the reflectivity curves shown as dashed lines in Fig. 15. Due to the large number of surfaces, the losses at the individual surfaces add up and the transmission drops rapidly in the red and near-infrared range.

[0163] In contrast, in the endoscope devices 110, 110', 110'' described above, anti-reflective surfaces can be used which are characterized by the curves shown as solid lines in Fig. 15 and 16. It can be seen that the reflectivity in the range between 400 nm and 1000 nm is possibly higher than the values ​​for a surface which is optimized for the visible range, but is at a low level over the entire range. In concrete terms, the

[0164] Reflectivity across the entire range is 1% at most. This results in a transmission that is also high across the entire range, in this case at least over 75%.

[0165] As mentioned, the endoscope devices 110, 110', 110'' have great advantages, especially when they are used for imaging in which a broad spectral range or at least wavelength ranges distributed over a broad spectral range are observed. It may therefore be expedient to use a broadband, preferably multimodal illumination device 150. This is described in more detail below by way of example. However, it is understood that the endoscope devices 110, 110', 110'' can also be combined with other suitable illumination devices.

[0166] The illumination device 150 can, as mentioned, be multimodal. The illumination device 150 can be operated in different illumination modes, in which it provides light for different imaging modes. In the present case, the illumination device 150 can be operated in three basic modes: a multispectral mode, a fluorescence mode, and a white light mode. Likewise, the imaging device 152 can be operated in different operating modes, specifically also at least in a multispectral mode, a fluorescence mode, and a white light mode. In the corresponding operating mode of the imaging device 152, the modes of the illumination device 150 are coordinated with one another.

[0167] Fig. 17 shows a schematic representation of the lighting device 150. The lighting unit 18 comprises a plurality of independently activatable lighting elements 20, 22, 24, 26, 28. These are configured to emit light according to different emission spectra in order to provide illumination light, i.e., the respective emission spectrum differs from lighting element to lighting element.

[0168] By way of example, the light elements 20, 22, 24, 26, 28 are designed as LEDs. Specifically, a first light element 20 is designed as a red LED, a second light element 22 as a dark-red LED, a third light element 24 as a blue LED, and a fourth light element 26 as a near-IR LED. The colored light elements 20, 22, 24, 26 each emit in a narrowband, for example, with an emission peak at approximately the wavelengths 660 nm (first light element 20), 770 nm (second light element 22), 460 nm (third light element 24), and 940 nm (fourth light element 26).

[0169] Furthermore, a fifth luminous element 28 is provided, which in this case is a white light luminous element, such as a white light LED. The fifth luminous element 28 emits, for example, in a spectral range of approximately 400 to 700 nm. In other embodiments, laser diodes can also be used, in particular as colored luminous elements.

[0170] Depending on the lighting mode, some of the lighting elements 20, 22, 24, 26, 28 are activated at least temporarily, whereas other lighting elements 20, 22, 24, 26, 28 may not be used in the lighting mode in question.

[0171] In the present case, a first group comprises the first light element 20 and the fourth light element 26. The first group can additionally comprise the light element 22 and / or the light element 24. The first group is used for multispectral imaging, wherein the included light elements 20, 26 and optionally 22 and 24 each serve as a support point. In multispectral mode, for example, the first light element 20 is first illuminated and an image is recorded. The fourth light element 26 is then illuminated and an image is recorded. The images are each based on remission, i.e. the light scattered back from the object to be imaged is observed. The two different support points can be used to obtain spectral information about the object to be imaged. For example, this can be used to assess certain tissue types, a perfusion state, a tissue texture or the like.

[0172] Furthermore, a second group comprises the first light-emitting element 20, the second light-emitting element 22, and the third light-emitting element 24. The second group is used for illumination in fluorescence imaging. For example, objects colored with suitably selected dyes can be specifically viewed here. Different dyes can also be introduced into different types of tissue or the like, which are then viewed simultaneously. By specifically exciting a specific dye, it is excited to fluoresce. The fluorescent light is then imaged. The first light-emitting element 20 is suitable, for example, for exciting the dye cyanine 5.5 (Cy 5.5). The second light-emitting element 22 is suitable for exciting the dye indocyanine green (ICG). The third light-emitting element 24 is suitable for exciting the dye fluorescein.

[0173] Furthermore, a third group comprises the fifth luminous element 28. In the present embodiment, the third group also comprises the first luminous element 20 and the third luminous element 24. The third group serves to provide illumination light for white light imaging. For this purpose, white light from the fifth luminous element 28 can be mixed with light from certain colored luminous elements, thereby compensating for spectral losses and / or allowing a color temperature to be specifically adjusted.

[0174] It can be seen that some of the lighting elements 20, 22, 24, 26, 28 are assigned to several groups, for example the first lighting element 20 to all three groups and the third lighting element 24 and possibly also the second lighting element 22 to the second and third groups.

[0175] Alternatively or additionally, it can also be provided that some or all of the light elements 20, 22, 24, 26, 28 are used in a hyperspectral mode. This generates a broad excitation spectrum. In combination with a suitable hyperspectral detector, spectral information relating to the object to be imaged can then be acquired across the entire visible and near-IR spectrum. For this purpose, the imaging device 14 can comprise a pushbroom arrangement as a hyperspectral detector. In other embodiments, a whiskbroom arrangement, a staring arrangement, and / or a snapshot arrangement is used. The imaging device 14 can be a hyperspectral imaging device. Regarding different methods of hyperspectral imaging and the components required for this purpose, reference is made to the specialist article "Review of spectral imaging technology in biomedical engineering: achievements and challenges" by Quingli Li et al.Published in Journal of Biomedical Optics 18 (10) , 100901, October 2013, and reference is made to the article "Medical hyperspectral imaging: a review" by Guolan Lu and Baowei Fei, published in Journal of Biomedical Optics 19(1) , 010901, January 2014.

[0176] The illumination unit 18 comprises two crossed beam splitters 30, 32. These each comprise an output side 42, 44, an input side 37, 41 opposite the output side 42, 44, and two opposite input sides 34, 36, 38, 40. All input sides 34, 36, 37, 38, 40, 41 guide incident light to the corresponding output side 42, 44. The output side 42 of a first crossed beam splitter 30 faces an input side 41 of the second crossed beam splitter 32. The output side 44 of the second crossed beam splitter 32 faces the optical interface 16. The two crossed beam splitters 30, 32 are preferably arranged coaxially to one another and / or to the optical interface.

[0177] The lighting unit 18 can comprise suitable optical elements such as lenses and / or mirrors (not shown). Several lenses 78, 80, 82, 84, 86, 88 are shown as examples in Fig. 17. A lens 78 is assigned, for example, to the optical interface 16 and couples light coming from the output side 44 of the second crossed beam splitter 32 into the optical interface 16. Furthermore, a lens 80, 82, 84, 86, 88 can be assigned to each of the lighting elements 20, 22, 24, 26, 28. A particularly high degree of compactness can be achieved in particular if the lighting elements 20, 22, 24, 26, 28 are each arranged on input sides 34, 36, 37, 38, 40 of the at least one crossed beam splitter 30, 32 without an intermediate mirror. The lighting elements 20, 22, 24, 26, 28 can then be moved very close to the at least one crossed beam splitter 30, 32. The crossed beam splitters 30, 32 each comprise two beam splitter elements 90, 92, 94, 96.These can generally be partially transparent, so that light from all input sides 34, 36, 37, 38, 40, 41 is redirected to the respective output side 42, 44. In the present embodiment, the beam splitter elements 90, 92, 94, 96 are selectively transparent. This is illustrated with further reference to Fig. 3. The beam splitter elements 90, 92, 94, 96 can be filters that reflect only in a defined area but otherwise have high transmission. Fig. 18 shows transmission curves 98, 100, 102, 104 of the beam splitter elements 90, 92, 94, 96 of the two crossed beam splitters 30, 32. Each of the colored light elements 20, 22, 24, 26 or each of the opposite input sides 34, 36, 38, 40 is assigned one of the beam splitter elements 90, 92, 94, 96.The beam splitter elements 90, 92, 94, 96 are selected such that they each reflect in the wavelength range in which the associated light element 20, 22, 24, 26 emits, but also largely transmit. For this purpose, notch filters can be used in the medium wavelength range, which can, for example, have the transmission spectra 100 and 102. At spectral edges, high-pass or low-pass filters can also be used instead of notch filters, see transmission spectra 98 and 104.

[0178] Due to the specific transmission spectra 98, 100, 102, 104 of the crossed beam splitters 30, 32, light from the fifth luminous element 28 is spectrally clipped. It may therefore be expedient, as already mentioned, to supplement the light blocked by the beam splitters 30, 32 in a targeted manner using the luminous elements 20 and 24, optionally also 22 and / or 26. This allows supplementation specifically in those spectral ranges in which the beam splitters 30, 32 absorb and / or reflect light from the fifth luminous element 28, but in any case does not transmit it to the optical interface 16. The additionally used luminous elements 20, 24 and optionally 22 are preferably operated at reduced power or with adjusted power. The aim here can be to at least largely restore the original spectrum of the fifth luminous element 28.In some embodiments, the fifth light-emitting element 28 can alternatively be a green light-emitting element or, more generally, a colored light-emitting element that emits primarily in the spectral range transmitted by the at least one beam splitter 30, 32. For example, in such embodiments the fifth light-emitting element 26 can be an LED with an emission peak at approximately 530 nm. A green laser diode is also suitable for this purpose. In this case, it can be provided that color mixing takes place in white light mode and, in particular, no individual white light source such as a white light LED is used, but rather white light from separate light elements is specifically mixed.

[0179] It is understood that, with suitable dyes, such a green luminescent element can also be used in fluorescence mode. Alternatively or additionally, it could be used in multispectral mode.

[0180] The illumination unit 18 defines a common optical path 54 into which the emitted light of the lighting elements 20, 22, 24, 26, 28 can be coupled. The common optical path 54 extends from the output side 44 of the second crossed beam splitter 32 to the optical interface. In this case, the common optical path 54 is arranged coaxially with the fifth lighting element 26.

[0181] In the embodiment shown, the lighting elements 20, 26 of the first group are arranged such that light emitted by the lighting elements 20, 26, starting from the respective lighting element 20, 26, up to the optical interface 16, each travels a light path of at least substantially the same length. The lighting elements 20, 26 of the first group each have a light-emitting surface 56, 58. The light-emitting surfaces 56, 62 are arranged equidistantly with respect to the common optical path 54. This is achieved in the present case in that the two lighting elements 20, 26 are arranged at the same distance from the beam splitter 32 assigned to them (in the present case, by way of example, the second beam splitter 32), in particular from its opposite input sides 38, 40. The light is coupled into the common optical path 54 by the crossed beam splitter 32.

[0182] The beam splitters 30, 32 are arranged in particular such that light-emitting surfaces 56, 58, 60, 62, 64 of the lighting elements 20, 22, 24, 26, 28 are each arranged equidistantly with respect to their associated crossed beam splitter 30, 32.

[0183] By using crossed beam splitters 30, 32 and lighting elements 20, 22, 24, 26, 28 that can be used jointly for different modes, the illumination unit 18 or the illumination device 12 has a high degree of compactness. Furthermore, the equidistant arrangement ensures that no spectral shifts occur when the imaging device 14 or its light guide is rotated relative to the optical interface 16.

[0184] It is understood that a different number of light-emitting elements 20, 22, 24, 26, 28 and / or a different number of crossed beam splitters 30, 32 may be used. The use of crossed beam splitters 30, 32 has proven particularly useful. However, in other embodiments, other types of beam splitters and / or other optical elements may be used to couple light from the light-emitting elements 20, 22, 24, 26, 28 into the optical interface 16.

[0185] List of reference symbols

[0186] 110 Endoscope device

[0187] 112 lens arrangement

[0188] 114 optical axis

[0189] 116 Eyepiece

[0190] 118 Objective

[0191] 120 first plane of symmetry

[0192] 122 rod lens

[0193] 124 Correction element

[0194] 126 optical system

[0195] 128 lens system

[0196] 130 first lens

[0197] 132 second lens

[0198] 134 Correction pair arrangement

[0199] 136 second plane of symmetry

[0200] 138 Correction pair arrangement

[0201] 140 third plane of symmetry

[0202] 142 third lens

[0203] 144 aperture

[0204] 146 Endoscope

[0205] 148 imaging system

[0206] 150 lighting device

[0207] 152 imaging device

[0208] 154 Image acquisition unit

[0209] 156 ad

[0210] 158 image capture sensors

[0211] 160 shaft

[0212] 162 distal end

[0213] 164 proximal end

[0214] 166 fourth plane of symmetry

[0215] 168 Correction pair arrangement

[0216] 170 anti-reflective surface

[0217] 172 lens

Claims

Claims 1. Endoscope device (110), in particular for hyperspectral and / or multispectral imaging, comprising a lens arrangement (112) which defines an optical axis (114) and which is configured to optically couple an eyepiece (116) to an objective (118), wherein the lens arrangement (112) is configured for a given focus both over a large part of the visible range and in the near-infrared range for a substantially equivalent transmission and imaging of light, wherein the lens arrangement (112) is symmetrical with respect to a first plane of symmetry (120) which is perpendicular to the optical axis (114), and wherein the lens arrangement (112) comprises: at least six rod lenses (122);at least two correction elements (124) which, together with the rod lenses (122), define an optical system (126) and which each comprise a lens system (128) with at least a first lens (130) and a second lens (132), wherein the first lens (130) is made of a first glass and the second lens (132) is made of a second glass, wherein the first glass and the second glass have different Abbe numbers and wherein a relative partial dispersion of the first glass and a relative partial dispersion of the second glass deviate in opposite ways from glass with normal dispersion; and at least one correction pair arrangement (134) comprising two of the correction elements (124) which are symmetrical to one another with respect to a second plane of symmetry (136) which is perpendicular to the optical axis (114); 2. Endoscope device (110) according to claim 1, wherein the first plane of symmetry (120) and the second plane of symmetry (136) are identical.

3. Endoscope device (110) according to claim 1 or 2, wherein the lens arrangement (112) comprises at least one further correction pair arrangement (138), wherein the further The correction pair arrangement (138) comprises two further correction elements (124) which are symmetrical to one another with respect to a third plane of symmetry (140) which is perpendicular to the optical axis (114). The endoscope device (110) according to claim 3, wherein the second plane of symmetry (136) and the third plane of symmetry (140) are different from the first plane of symmetry (120). The endoscope device (110) according to one of the preceding claims, wherein the correction elements (124) each comprise at least one third lens (142) which is made of the first glass. The endoscope device (110) according to one of the preceding claims, wherein the correction elements (124) are each formed integrally with a rod lens (122). The endoscope device (110) according to one of the preceding claims, wherein the correction pair arrangement (134) comprises at least one aperture (144) which is arranged in the region of the second plane of symmetry (136).Endoscope device (110) according to one of the preceding claims, wherein the second lens (132) is a convex lens. Endoscope device (110) according to one of claims 1 to 7, wherein the second lens (132) is a concave lens. Endoscope device (110) according to one of the preceding claims, wherein the lens arrangement (112) enables optical images in the range from 400 nm to 1000 nm that have an RMS spot radius of at most 40 pm, preferably at most 35 pm, and more preferably at most 30 pm. Endoscope device (110) according to one of the preceding claims, wherein the lens arrangement (112) enables diffraction-limited optical images in the range from 480 nm to 1000 nm. Endoscope device (110) according to one of the preceding claims, wherein the lens arrangement (112) has a largest RMS spot radius of at most 8 pm, preferably at most 6 pm, and preferably at most 4 pm. Endoscope device (110) according to one of the preceding claims, wherein the rod lenses (122) and the correction elements (124) have anti-reflective surfaces (164) that operate in the visible and near-infrared ranges. Endoscope device (110) according to claim 13, wherein the anti-reflective surfaces (164) each cause an average reflection of at most 2%, preferably of at most 1%, and preferably of at most 0.6% in the range from 400 nm to 1000 nm. Endoscope device (110) according to claim 13 or 14, wherein the anti-reflective surfaces (164) in the range from 400 nm to 1000 nm each cause a maximum reflection of at most 3%, preferably of at most 2% and preferably of at most 1%.Endoscope device (110) according to one of the preceding claims, wherein the lens arrangement has an average transmission of at least 70%, preferably at least 80%, and particularly preferably at least 85% in the range from 400 nm to 1000 nm. Endoscope device (110) according to one of the preceding claims, wherein the lens arrangement has a minimum transmission of at least 60%, preferably at least 70%, and particularly preferably at least 80% in the range from 400 nm to 1000 nm. Endoscope device (110) according to one of the preceding claims, further comprising the eyepiece (116) and / or the objective lens (118). Correction pair arrangement (134) for a lens arrangement (112) of an endoscope (146), comprising at least two correction elements (124) which define an optical axis (114) and which are configured, together with a plurality of rod lenses (122), to define an optical system (126) and which each comprise a lens system (128) with at least a first lens (130) and a second lens (132), wherein the first lens (130) is made of a first glass and the second lens (132) is made of a second glass, wherein the first glass and the second glass have different Abbe numbers and wherein a relative partial dispersion of the first glass and the second glass deviates in an opposite manner from glass with normal dispersion; wherein the correction elements (124) are symmetrical to one another with respect to a plane of symmetry (120, 132, 140, 166) which is perpendicular to the optical axis.Correction pair arrangement (134) according to claim 19, further comprising an aperture (144) arranged in the region of the plane of symmetry (120). Endoscope (146) with an endoscope device (110) according to one of claims 1 to 18 and / or with a correction pair arrangement (134) according to claim 19 or 20. Imaging system (148) comprising: an illumination device (150) configured to provide illumination light in both the visible range and the near-infrared range; an endoscope device (110) according to one of claims 1 to 18 and / or an endoscope (146) according to claim 21; and an imaging device (152) with an image acquisition unit (154) configured to acquire multispectral and / or hyperspectral image data.

Images