Optical element for light concentration and manufacturing method for an optical element for light concentration

Description

[0001] The invention relates to an optical element for light concentration. It also relates to a spectrometer and a mobile device. Furthermore, the invention relates to a manufacturing process for an optical element for light concentration. State of the art

[0002] US Patent 9,316,540 B1 describes one embodiment of a spectrometer which comprises a light-focusing lens and an aperture as its light-incidence / frontal optics. A diffuser is arranged downstream of the light-incidence / frontal optics.

[0003] Further examples of the state of the art can be found in the documents

[0004] US20060072222, WO2007072856, US2014307447, DE102016112750 and US3780357. Disclosure of the invention

[0005] The invention provides an optical element for light concentration with the features of claim 1, a spectrometer with the features of claim 6, a mobile device with the features of claim 7 and a manufacturing method for an optical element for light concentration with the features of claim 8. Advantages of the invention

[0006] The present invention enables the integration of a diffuser into an optical element for light concentration. The optical element according to the invention can thus additionally fulfill the functions of a diffuser, thereby eliminating the need for a conventionally required diffuser. Therefore, the present invention makes it possible to realize optical devices with an optical element for light concentration, whereby diffuse light can be generated by means of the optical element for light concentration, even though the respective optical device does not have a conventional diffuser. By eliminating the conventional diffuser without any disadvantages, the respective optical device can be manufactured more cost-effectively, lighter, and / or with a smaller installation space requirement. The present invention thus facilitates the miniaturization of the respective optical device.

[0007] The optical element created by the present invention can be described as a diffuser-concentrator. It can be used in a variety of applications.

[0008] In the invention, the optical element comprises a light transmission body which has a light-collecting surface with a first area on one side and a light-emission surface with a second area smaller than the first on the other. The optical element can thus be advantageously used to concentrate light incident through the light entrance aperture onto a relatively small input aperture downstream of the light exit aperture, such as the input aperture of a spectrometer.

[0009] Furthermore, at least one central longitudinal axis extending from the light-collecting surface to the light-emitting surface and intersecting the light transmission body can be defined, wherein the diffusivity distribution of the light transmission body is rotationally symmetric with respect to the central longitudinal axis. The light transmission body thus exhibits an anisotropic diffusivity distribution, which is advantageous both for generating diffuse light and for concentrating the generated diffuse light.Additionally, the first sub-region with the first diffusivity is located at the light-emitting surface and has a varying layer thickness, which is minimal along the central longitudinal axis and maximal at the at least one reflective surface, while the second sub-region with at least the second diffusivity is located at the light-collecting surface and has a varying layer thickness, which is maximal along the central longitudinal axis and minimal at the at least one reflective surface. As explained in more detail below, such a light transmission body is relatively easy to manufacture.

[0010] As an optional further development, the second part of the light transmission body can have a laminate structure consisting of laminate layers with different diffusivities arranged around the central longitudinal axis. Such a light transmission body is also relatively easy to manufacture.

[0011] Preferably, the light transmission body is formed at least partially from at least one matrix material transmitting for the specified wavelength range, which is mixed with particles and / or gas bubbles scattering for the specified wavelength range, as the at least one medium diffusing for the specified wavelength range. For example, the light transmission body can comprise PDMS, PMMA, and / or SU8 as the matrix material transmitting for the specified wavelength range and / or titanium dioxide particles, silicon dioxide particles, melamine resin particles, and / or polystyrene particles as the particles scattering for the specified wavelength range. This allows for the use of cost-effective and easily processed materials for manufacturing the light transmission body.

[0012] In a further advantageous embodiment of the optical element, the light transmission body is at least partially formed from at least one porous material as the at least one medium diffuse for the specified wavelength range. In this case, the local diffusivity can be easily varied by varying the pore size of the pores formed in the porous material.

[0013] The advantages described above are achieved, for example, in a spectrometer with such an optical element. As explained in detail below, a wide variety of different spectrometer types can be equipped with the corresponding optical element. The present invention is therefore versatile.

[0014] The advantages described above are often also present in a mobile device equipped with a corresponding optical element and / or such a spectrometer. Since the present invention facilitates the miniaturization of optical devices, it also contributes to the miniaturization of mobile devices / portable devices, such as a mobile phone or a smartphone. Furthermore, the present invention facilitates the integration of an optical device / spectrometer equipped with the optical element according to the invention into the respective mobile device / portable device.

[0015] Furthermore, implementing a corresponding manufacturing process for an optical element for light concentration also yields the advantages already explained above. It is expressly noted that the manufacturing process can be further developed according to the embodiments of the optical element described above. Brief description of the drawings

[0016] Further features and advantages of the present invention are explained below with reference to the figures. They show: Fig. 1 a schematic representation of a first embodiment of an optical element for light concentration; Fig. 2 a schematic representation of a second embodiment of an optical element for light concentration; Fig. 3 a schematic representation of a first embodiment of a spectrometer; Fig. 4 a schematic representation of a second embodiment of a spectrometer; and Figs. 5a to 5f schematic cross-sections to illustrate an embodiment of a manufacturing process for an optical element for light concentration. Embodiments of the invention

[0017] The term "diffusivity," as used below, refers to a measure of how "directed" light propagates (unidirectionally) through a body from at least one diffuse medium. Diffusivity is directly proportional to the mean free path between two scattering events of the transmitted light. (The directed speed of light of individual photons remains unaffected by scattering events.)

[0018] Fig. 1 shows a schematic representation of a first embodiment of the optical element for light concentration.

[0019] The in Fig. 1 The schematically represented optical element 10 is designed to concentrate light within a specific wavelength range. This wavelength range can be, for example, the optical spectrum, a wavelength range from 400 nm (nanometers) to 1100 nm (nanometers), a wavelength range from 780 nm (nanometers) to 1100 nm (nanometers), a wavelength range from 1100 nm (nanometers) to 2500 nm (nanometers), a wavelength range from 400 nm (nanometers) to 2500 nm (nanometers), or a wavelength range from 780 nm (nanometers) to 2500 nm (nanometers). However, the wavelength ranges listed here are only examples.

[0020] The optical element 10 comprises a retaining sleeve 12, which is shaped such that a light-transmitting volume is enclosed by at least one reflective partial surface 12a of the retaining sleeve 12. The retaining sleeve 12 is preferably understood to be a "stabilizing" retaining sleeve 12. The at least one reflective partial surface 12a of the retaining sleeve 12, which encloses the light-transmitting volume, can also be described as a "reflective side wall." For example, the retaining sleeve 12 can be made (entirely) of at least one material that reflects (the specified wavelength range), such as, in particular, a metal, a semiconductor, a plastic (such as PTFE / polytetrafluoroethylene or Spectralon), and / or a ceramic (e.g., Accuratus Accuflect). Likewise, at least one layer that reflects (the specified wavelength range) can be applied to the at least one reflective partial surface 12a of the retaining sleeve 12.The at least one layer reflecting (the specified wavelength range) can in particular be a stack of layers consisting of several layers reflecting (the specified wavelength range) or a Bragg mirror.

[0021] Furthermore, the optical element 10 has a light transmission body 14 with which the light transmission volume is completely filled. The light transmission body 14 is transmitting at least for the specified wavelength range. In particular, the light transmission body 14 can be transparent at least for the specified wavelength range. Additionally, the light transmission body 14 is at least partially formed from at least one medium that is diffuse for the specified wavelength range, wherein the light transmission body 14 has at least a first sub-area 16a with (at least) a first diffusivity D1 and a second sub-area 16b with (at least) a second diffusivity D2 that differs from the first diffusivity D1.Due to the design of the light transmission body 14 from at least one diffuse medium (for the specified wavelength range), the optical element 10 is advantageously suited for generating diffuse light with a (essentially) homogeneous angular distribution. The optical element 10 is thus suitable for use in a variety of optical systems that require the most homogeneous intensity and angular distribution of light possible. At the same time, due to the different diffusivities D1 and D2 in the at least two sub-regions 16a and 16b of its light transmission body 14, the optical element 10 can be advantageously used to concentrate light in the specified wavelength range. It is particularly suitable for concentrating light in the specified wavelength range from a larger area to a smaller area while still homogenizing its initial angular distribution.The optical element 10 can therefore be described as a diffuser-concentrator.

[0022] Compared to an optical lens, the optical element 10, which can be described as a diffuser-concentrator, offers an increase in its "light-collecting efficiency" while maintaining an extremely low profile. The retaining sleeve 12 / the light transmission body 14 are shaped such that the light flow volume / light transmission body 14 has a light-inlet aperture / light-collecting surface 18 on one side with a first area and a light-outlet aperture / light-outlet surface 20 on the other side with a second area smaller than the first. The distance between the light-inlet aperture / light-collecting surface 18 and the light-outlet aperture / light-outlet surface 20, which can be described as the height of the optical element 10, can be, for example, smaller than the maximum dimensions of the light-inlet aperture / light-collecting surface 18 and / or the maximum dimensions of the light-outlet aperture / light-outlet surface 20.In particular, the distance between the light inlet aperture / light collecting area 18 and the light outlet aperture / light exit surface 20 can be less than half the maximum extent of the light inlet aperture / light collecting area 18 and / or less than half the maximum extent of the light outlet aperture / light exit surface 20.

[0023] The openings / surfaces 18 and 20 can be, for example, round, elliptical, square, and / or rectangular. The light transmission volume / light transmission body 14 can thus have a frustoconical or truncated pyramidal geometry. The openings / surfaces 18 and 20 can also be bounded by a general polygon. The first area of ​​the light entry opening / light collection surface 18 can, for example, be between 15 mm² and 50 mm². The second area of ​​the light exit opening / light exit surface 20 can, for example, be between 3 mm² and 12 mm². For example, the ratio of the first area to the second area can be in the range of 2 to 8.

[0024] Due to its comparatively low height, its relatively small apertures / areas 18 and 20, and its suitability as a diffuser-concentrator, the optical element 10 enables an extremely compact design of the optical device equipped with it. In addition, the advantageous properties of the optical element 10 facilitate the miniaturization of the optical device equipped with it. The optical element 10, which can be used as a diffuser-concentrator, can, for example, be used for the entrance aperture of a (miniaturized) spectrometer.

[0025] In the example of the Fig. 1 The light transmission body 14 has a layered structure consisting of only two sub-regions 16a and 16b with different diffusivities D1 and D2. Furthermore, a central longitudinal axis 22 can be defined for the optical element 10, extending from the light entrance aperture / light collection surface 18 to the light exit aperture / light exit surface 20 and intersecting the light transmission body 14, wherein the diffusivity distribution of the light transmission body 14 is rotationally symmetric with respect to the central longitudinal axis 22. The first sub-region 16a with the first diffusivity D1 lies at the light exit surface 20 and can therefore be referred to as the exit region 16a of the light transmission body 14. The exit area 16a has a varying layer thickness (oriented perpendicular to the light exit surface 20), with the layer thickness of the exit area 16a being minimal at the central longitudinal axis 22 (e.g.The diffusivity D2 of the first part of the light transmission body 14 is at its maximum at the central longitudinal axis 22 and is at its minimum (e.g., zero) at the at least one reflective partial surface 12a. Similarly, the second part 16b, with the second diffusivity D2, which lies at the light-collecting surface 18 and can be designated as the entry area 16b of the light transmission body 14, also has a varying layer thickness (oriented perpendicular to the light-collecting surface 18). The varying layer thickness of the entry area 16b of the light transmission body 14 (oriented perpendicular to the light-collecting surface 18) is at its maximum at the central longitudinal axis 22 and is at its minimum (e.g., zero) at the at least one reflective partial surface 12a of the retaining sleeve 12.

[0026] At the in Fig. 1 In the light transmission body 14 shown, the second diffusivity D2 is greater than the first diffusivity D1. The light transmission body 14 of Fig. 1 This results in an anisotropic, direction-dependent diffusivity distribution, concentrating the light transmitted through the light transmission body 14 from the larger light-collecting area 18 onto the smaller light-exiting area 20, and possibly onto an entrance aperture located downstream. The optical element 10 is therefore well-suited for use as a diffuser-concentrator. (Diffuse media commonly used in conventional diffusers generally have an isotropic diffusivity / diffusivity distribution. Light propagation in a conventional diffuser therefore usually occurs at the same rate in all directions.)

[0027] To determine / adjust the diffusivity distribution / the (local) diffusivities D1 and D2 in the light transmission body 14, randomly arranged scattering centers can be used, which lead to multiple scattering of the light transmitted through the light transmission body 14 and to randomizing its direction of propagation. (The scattering centers can also be described as "dielectric scatterers.") The (local) diffusivity D1 or D2 is (due to its proportionality to the mean free path between two scattering events) inversely proportional to a local concentration c1 and c2 of randomly arranged scattering centers in the light transmission body 14. In the example of the Fig. 1 The first subregion 16a with the first diffusivity D1 has a first local concentration c1 of randomly arranged scattering centers, which is greater than a second local concentration c2 of randomly arranged scattering centers of the second subregion 16b with the second diffusivity D2.

[0028] Preferably, the light transmission body 14 is formed at least partially from at least one transmitting / transparent matrix material for the specified wavelength range, which is mixed with particles and / or gas bubbles / air bubbles (as scattering centers) that scatter the specified wavelength range (as the at least one diffuse medium for the specified wavelength range). (As mentioned above, in this case, the at least two sub-regions 16a and 16b of the light transmission body 14 have different concentrations c1 and c2 of scattering particles and / or gas bubbles.) The at least two sub-regions 16a and 16b of the light transmission body 14 can be formed either from the same matrix material or from different matrix materials. For example, PDMS (polydimethylsiloxane), PMMA (polymethyl methacrylate), and / or SU8 (photoresist from Microchem Corp.) can be used.) as the at least one matrix material that transmits / transmits within the specified wavelength range. The light transmission body 14 can, for example, contain titanium dioxide particles (TiO2), silicon dioxide particles (SiO2), melamine resin particles (MF), and / or polystyrene particles as the particles that scatter the specified wavelength range. Thus, cost-effective and easily processed materials can be used to form the light transmission body 14.

[0029] Alternatively, the light transmission body 14 can also be formed, at least partially, from at least one porous material (as the at least one medium diffuse for the specified wavelength range). For example, silicon can be used as the at least one porous material. In this case, the at least two sub-regions 16a and 16b of the light transmission body 14 can have different concentrations c1 and c2 of pores and / or different mean pore diameters. (The at least two sub-regions 16a and 16b of the light transmission body 14 can be formed either from the same porous material or from different porous materials.)

[0030] The components of the optical element 10 described above can be arranged / formed on a substrate 24 that transmits / is transparent for the specified wavelength range. However, the optical element 10 can also exist without the substrate 24.

[0031] Fig. 2 shows a schematic representation of a second embodiment of an optical element for light concentration.

[0032] The in Fig. 2 The schematically depicted light transmission body 14 has the entrance area 16b with the second diffusivity D2 already described above, wherein the entrance area 16b is located at the light-collecting surface 18 and has a varying layer thickness (oriented perpendicular to the light-collecting surface 18), which is maximum at the central longitudinal axis 22 and becomes minimum (e.g., approaches zero) at the at least one reflective partial surface 12a of the retaining sleeve 12. In contrast to the previously described embodiment, the exit area 16c to 16f of the light transmission body 14 has Fig. 2 However, a laminate structure consisting of laminate layers 16c to 16f extending around the central longitudinal axis 22 with different diffusivities D3 to D6 is present. (The exit area 16c to 16f formed from the laminate layers 16c to 16f again has a varying layer thickness (oriented perpendicular to the light exit surface 20), which becomes minimal (e.g., approaches zero) at the central longitudinal axis 22 and is maximal at the at least one reflective partial surface 12a.The diffusivities D3 to D6 of the laminate layers 16c to 16f can be configured such that a laminate layer 16d with a diffusivity D4 below the second diffusivity D2 lies between two laminate layers 16c and 16e, each with a diffusivity D3 and D5 above the second diffusivity D2, and a laminate layer 16e with a diffusivity D5 above the second diffusivity D2 lies between two laminate layers 16d and 16f, each with a diffusivity D4 and D6 below the second diffusivity D2. For simplicity, the diffusivities D3 and D5 and / or the diffusivities D4 and D6 can be equal. (The illustration of the "higher" diffusivity D3 in the middle of the exit region 16c to 16f is only illustrative; alternatively, a "lower" diffusivity could also be configured in the middle.)Accordingly, either the local concentrations c3 and c5 can be smaller than the local concentration c2 and the local concentrations c4 and c6 larger than the local concentration c2, or the local concentrations c3 and c5 can be larger than the local concentration c2 and the local concentrations c4 and c6 smaller than the local concentration c2.

[0033] Light propagation along the laminate layers 16c to 16f is thus preferential compared to light propagation perpendicular to the laminate layers 16c to 16f. The orientation of the laminate layers 16c to 16f towards the center of the light-emitting surface 20 therefore results in a concentration of the light diffusing through the light-transmitting body 14. The optical element of the Fig. 2 It is therefore well suited as a diffuser concentrator.

[0034] Regarding further features of optical element 10 of the Fig. 2 Reference is made to the preceding embodiment.

[0035] Instead of a layered structure of the light transmission body 14, as explained in the preceding examples, the light transmission body 14 can also exhibit a gradual variation of the local diffusivity, for example by means of a gradual variation of the local concentrations of scattering centers.

[0036] Fig. 3 shows a schematic representation of a first embodiment of a spectrometer.

[0037] The in Fig. 3 The schematically depicted spectrometer is an example of a static Fourier transform spectrometer. The spectrometer has an optical element 10 configured as a diffuser-concentrator as its input aperture. (Alternatively, such an optical element can also be used in a beam path of a spectrometer / microspectrometer.)

[0038] Adjacent to the light-emitting surface 20 of the optical element 10 / its light transmission body 14 is a polarizer 30, which polarizes the light exiting the light transmission body 14 (at an angle of 45° to the image plane). Downstream of the polarizer 30 is a Savart element 32 consisting of two differently oriented birefringent crystals, which split the polarized light into a beam polarized parallel / horizontally (to the image plane) and a beam polarized perpendicular / vertically (to the image plane). Depending on their polarization and angle of incidence, the two beams travel different optical path lengths through the two birefringent crystals of the Savart element 32. The optical path length difference between the two beams thus depends on the angle of incidence of the light exiting the optical element 10.Subsequently, another polarizer 34 projects the two beams back together (at an angle of 45° to the image plane) so that the light from both beams can interfere with each other. A lens system 36 then focuses all light rays with the same angle of incidence onto the same detection area of ​​a detector array 38. Depending on the phase difference, the light interferes constructively or destructively. Thus, a 2D interference pattern is obtained using the detector array 38, from which a spectrum can be determined by means of a Fourier transform.

[0039] The spectrometer's equipment Fig. 3 The optical element 10 ensures uniform illumination of the spectrometer components 30 to 36 located downstream of the optical element 10. Due to the concentration of the light occurring on the relatively large light collection area 18 onto the significantly smaller light emission area 20, the "high-intensity" spectrometer can be manufactured with a comparatively small volume.

[0040] Fig. 4 shows a schematic representation of a second embodiment of a spectrometer.

[0041] The means of the Fig. 4 The spectrometer type shown has an optical element 10 designed as a diffuser-concentrator as its input aperture. (Alternatively, in this spectrometer type, the optical element 10 can also be used in a beam path.)

[0042] The incident light is first uniformly distributed in intensity and angle by means of the optical element 10. The light exiting the optical element 10 is optionally filtered by means of a bandpass filter 40. An angle-dependent filter element 42, such as a Fabry-Pérot filter 42, is placed downstream of the (optional) bandpass filter 40. The light exiting the angle-dependent filter element 42 is then focused onto a detector array 46 by means of a lens 44 such that different angles of incidence or wavelengths strike different detection areas of the detector array 46.

[0043] Even in the embodiment of the Fig. 4 The optical element 10 enables the most homogeneous intensity and angle distribution possible.

[0044] All the spectrometers described above have a compact design due to their optical element 10. By increasing the light-collecting area 18 while maintaining the same dimensions of the subsequent components, more light can be collected. Alternatively, the respective spectrometer can also be minimized without significant additional costs by reducing the light-exiting area 20 (compared to the light-collecting area 18).

[0045] All the optical elements and spectrometers described above are well suited for use in a mobile device, such as a mobile phone or a smartphone, due to their comparatively small size.

[0046] Fig. 5a bis 5f The figures show schematic cross-sections to illustrate one embodiment of the manufacturing process for an optical element for light concentration.

[0047] In carrying out the manufacturing process described here, a retaining sleeve 12 of the subsequent optical element is first formed such that a light transmission volume is enclosed by at least one reflective partial surface 12a of the retaining sleeve 12. For this purpose, a sleeve material 50, such as a semiconductor material (silicon), a metal and / or a plastic, is deposited on a substrate 24 (see Fig. 5a Preferably, a substrate 24 that transmits / transmits within the wavelength range specified for the light concentration is used. In this case, subsequent removal of the substrate 24 is unnecessary.

[0048] Fig. 5b Figure 1 shows the structuring of the retaining sleeve 12 from the sleeve material 50. The structuring of the sleeve material 50 can be carried out, for example, by means of an anisotropic etching process.

[0049] Instead of the ones in the Fig. 5a und 5b The retaining sleeve 12 can also be manufactured using injection molding, lathe clamping, embossing, milling, 3D printing, or grayscale lithography, as described in the process steps. Alternatively, a wafer can be used and anisotropically structured into the desired shape to produce a large number of retaining sleeves 12.

[0050] In the event that the reflectivity of the at least one reflective partial surface 12a surrounding the light flow volume of the retaining sleeve 12 is still insufficient, the at least one partial surface 12a can be further smoothed (in particular by a reflow process) and / or mirrored (e.g. by applying at least one reflective layer).

[0051] In the subsequent process steps, a light transmission body 14 of the later optical element 10 is formed such that the light transmission body 14 is transmitting at least for the specified wavelength range. The light transmission volume is completely filled with the light transmission body 14. The light transmission body 14 is formed at least partially from at least one medium that is diffuse for the specified wavelength range, such that the light transmission body 14 has at least a first sub-region 16a with (at least) one first diffusivity D1 and a second sub-region 16b with (at least) a second diffusivity D2 that differs from the first diffusivity D1. By way of example, in the embodiment described here, the light transmission body 14 is formed only with the two sub-regions 16a and 16b with a total of two different diffusivities D1 and D2.However, the feasibility of the manufacturing process described here is not limited to such a light transmission body 14.

[0052] In the embodiment described here, first, as in Fig. 5c As shown schematically, a matrix material (e.g., PDMS) with an initial (local) concentration c1 of scattering particles used as scattering centers is filled into the volume through which the light will pass. The scattering particles can be, for example, titanium dioxide particles.

[0053] Fig. 5d Figure 1 shows an embossing process by which the later first sub-section 16a of the light transmission body 14 is brought into its shape as described above. The embossing process can be carried out easily and reliably using techniques known from nanoembossing lithography. Fig. 5e shows the formed first sub-area 16a with the first diffusivity D1 after removal of a stamp 52 used for embossing.

[0054] In a further procedural step, which is carried out by means of the Fig. 5f As shown schematically, the same matrix material, but with a second concentration c2 of scattering particles that differs from the first concentration c1, is poured into the remaining, unfilled portion of the light transmission volume. A doctor blade 54 can be used to create a smooth light-collecting surface 18 on the light transmission body 14 completed in this way. The substrate 24 can then be removed if necessary.

[0055] The process steps described above can also be performed at the wafer level. In a further training course using the Fig. 5a bis 5f Several embossing steps can be carried out in the schematically depicted manufacturing process to achieve the desired effect. Fig. 2to create the lamellar structure shown.

[0056] The use of scattering particles as randomly distributed scattering centers described above is merely an example. A (local) concentration c1 or c2 of scattering centers in the light transmission body 14 can, for example, be determined by means of a Monte Carlo simulation of a desired light propagation. The larger the quotient of the first area of ​​the light-collecting surface 18 divided by the second area of ​​the second area of ​​the light-emitting surface 20, and the smaller the distance between the light-collecting surface 18 and the light-emitting surface 20, the more advantageous a strong diffusivity contrast.

Claims

1. Optical element (10) for light concentration for a predetermined wavelength range, having: a holding sleeve (12), which is shaped in such a way that a light passage volume is framed by at least one reflective partial surface (12a) of the holding sleeve (12); and a light transmission body (14), with which the light passage volume is completely filled and which is transmissive at least for the predetermined wavelength range, wherein the light transmission body (14) has a light collection surface (18) with a first area content on a first side and a light exit surface (20) with a second area content, which is less than the first area content, on a second side; wherein the light transmission body (14) is formed at least partially from at least one medium which is diffuse for the predetermined wavelength range and has at least a first subregion (16b) with at least a first diffusivity (D1, D3 to D6) and a second subregion (16a) with at least a second diffusivity (D2), which is different from the first diffusivity (D1, D3 to D6), and wherein at least one central longitudinal axis (22) extending from the light collection surface (18) to the light exit surface (20) and intersecting the light transmission body (14) can be defined, and wherein the diffusivity distribution of the light transmission body (14) is rotationally symmetrical with respect to the central longitudinal axis (22), characterized in that the first subregion (16b) with the first diffusivity (D1, D3 to D6) lies on the light exit surface (20) and has a varying layer thickness, which is minimal on the central longitudinal axis (22) and maximal on the at least one reflective partial surface (12a), and wherein the second subregion (16a) with at least the second diffusivity (D2) lies on the light collection surface (18) and has a varying layer thickness, which is maximal on the central longitudinal axis (22) and minimal on the at least one reflective partial surface (12a).

2. Optical element (10) according to Claim 1, wherein the second subregion (16a) of the light transmission body (14) has a laminate structure consisting of laminate layers (16c to 16f) with different diffusivities (D3 to D6) extending around the central longitudinal axis (22).

3. Optical element (10) according to one of the preceding claims, wherein the light transmission body (14) is formed at least partially from at least one matrix material which is transmissive for the predetermined wavelength range and is mixed with particles and / or gas bubbles which scatter the predetermined wavelength range as the at least one medium which is diffuse for the predetermined wavelength range.

4. Optical element (10) according to Claim 3, wherein the light transmission body (14) has PDMS, PMMA and / or SU8 as the at least one matrix material which is transmissive for the predetermined wavelength range, and / or titanium dioxide particles, silicon dioxide particles, melamine resin particles and / or polystyrene particles as the particles that scatter the predetermined wavelength range.

5. Optical element (10) according to either of Claims 1 and 2, wherein the light transmission body (14) is formed at least partially from at least one porous material as the at least one medium which is diffuse for the predetermined wavelength range.

6. Spectrometer having an optical element (10) according to one of the preceding claims.

7. Mobile apparatus having an optical element (10) according one of Claims 1 to 5 and / or a spectrometer according to Claim 6.

8. Production method for an optical element (10) for light concentration for a predetermined wavelength range, comprising the steps of: forming a holding sleeve (12), which is shaped in such a way that a light passage volume is framed by at least one reflective partial surface (12a) of the holding sleeve (12); and forming a light transmission body (14) in such a way that the light transmission body (14) is transmissive at least for the predetermined wavelength range and that the light transmission body (14) has a light collection surface (18) with a first area content on a first side and a light exit surface (20) with a second area content, which is less than the first area content, on a second side; wherein the light passage volume is completely filled with the light transmission body (14) and wherein the light transmission body (14) is formed at least partially from at least one medium which is diffuse for the predetermined wavelength range in such a way that the light transmission body (14) has at least a first subregion (16b) with at least a first diffusivity (D1, D3 to D6) and a second subregion (16a) with at least a second diffusivity (D2), which is different from the first diffusivity (D1, D3 to D6), and that at least one central longitudinal axis (22) extending from the light collection surface (18) to the light exit surface (20) and intersecting the light transmission body (14) can be defined, and the diffusivity distribution of the light transmission body (14) is rotationally symmetrical with respect to the central longitudinal axis (22), characterized in that the light transmission body (14) is formed in such a way that the first subregion (16b) with the first diffusivity (D1, D3 to D6) lies on the light exit surface (20) and has a varying layer thickness, which is minimal on the central longitudinal axis (22) and maximal on the at least one reflective partial surface (12a), and that the second subregion (16a) with at least the second diffusivity (D2) lies on the light collection surface (18) and has a varying layer thickness, which is maximal on the central longitudinal axis (22) and minimal on the at least one reflective partial surface (12a).