WO2010057553A1

WO2010057553A1 - Optical light scattering device

Info

Publication number: WO2010057553A1
Application number: PCT/EP2009/007440
Authority: WO
Inventors: Andreas Wienkamp
Original assignee: Cerion Gmbh
Priority date: 2008-11-19
Filing date: 2009-10-16
Publication date: 2010-05-27
Also published as: DE202008015402U1; EP2359167A1

Abstract

The invention relates to an optical light scattering device having a transparent scattering body, and having at least one light source, the emitted light thereof being coupled into the scattering body and scattered upon passing through inhomogeneities present in the interior, characterized in that the inhomogeneities are formed as surface markings and/or sub-surface markings made in the scattering body by electromagnetic radiation.

Description

Optical light scattering unit

description

The invention relates to an optical light scattering unit, comprising a transparent scattering body, and having at least one light source whose emitted light is coupled into the scattering body and is scattered as it passes through inhomogeneities present in the interior.

Transparent scattering means a scattering body which is completely or at least partially permeable to the coupled-in light and the said one

Light from the light source is not completely absorbed. The inside existing

Inhomogeneities can extend to the surface of the scattering body or be present on the surface and protrude into the interior of the scattering body.

In any case, the inhomogeneity in question extends into the interior of the scattered body, provided it is present on the surface or is completely within

Interior of the scatterer arranged.

In the context of the invention predominantly scattering takes place in the forward direction, in which the light beams emitted by the light source are deflected at the individual scattering centers present in the scattering body at an angle of not more than 90 °. Of course, it can also come to a scatter in the reverse direction. Usually, however, the intensity of the scattered light in the forward direction is greater than the intensity of the scattered light in the reverse direction.

Optical light scattering units of the structure described at the outset are widely known in practice and are described, for example, in the context of DE 101 53 380 A1. This is about a lamp with a translucent disc, which is equipped with a microstructure. DE 10 2004 049 260 A1 describes a similar structure in order to illuminate containers or containers in general and to record their image with the aid of one or more cameras. From DE 10 2006 061 164 A1, a light-emitting device has become known in which a radiation source interacts with a curved light guide body. The radiation emitted by the radiation source is coupled into the light guide body and coupled out at an angle to its longitudinal axis.

Finally, DE 101 23 263 B4 deals with a light guide system for the interior of a motor vehicle. It is all about a large-scale, homogeneous and glare-free brightening of a vehicle roof in the overhead area of vehicle occupants. For this purpose, an optical fiber for guiding light is provided in addition to the actual light source. The light guide is formed flat, wherein the coupling of the light takes place at one or more side surfaces. The decoupling of the light is achieved by roughening, embossing or drilling with a specific structure.

The state of the art can not convince in all points. Because the arrangement and introduction of the scattering centers inside the scattering body often requires an increased mechanical complexity and can be realized only with great effort targeted and with a certain arrangement and orientation. This is where the invention starts.

The invention is based on the technical problem of further developing such an optical light scattering unit so that the scattering centers can be introduced into the transparent scattering body in a simple and defined manner.

To solve this technical problem, a generic optical light scattering unit is characterized in that the inhomogeneities or scattering centers in the transparent scattering body are formed as surface markings and / or sub-surface markings introduced by electromagnetic radiation. In the context of the invention, therefore, the inhomogeneities in the scattering body are not defined by mechanical or chemical treatment of the scattering body in the interior or on its surface. Rather, it is characterized by the fact that with the aid of the electromagnetic radiation, markings are introduced under the surface, so-called sub-surface markings or in general structures or sub-surface structures. Alternatively or additionally, surface markings can also be realized with the aid of the electromagnetic radiation. These surface markings are flanked in principle with indentations and / or formations on the surface, which represent the actual inhomogeneities in the interior of the scattering body.

Overall, the invention is based on the finding that energy densities of several J / cm ² can be achieved with the aid of the electromagnetic radiation coupled into the scatterer, so that at the location of the focal point MoI binding bonds are permanently destroyed and, in general, a plasma is generated.

As a consequence of this, microscopic structures in the form of crack stars or (smooth-walled) recesses or depressions, which in terms of shape, size and position are essentially located in the material or on its surface by the parameters power of the electromagnetic radiation and focal length of an associated optics to focus on. This is generally known in connection with the writing and reading of information in transparent material body, as the DE 237 972 A3, US 3,715,734 or DE 691 25 378 T2 occupy. In addition, reference should be made to DE 199 25 801 B4, which describes a method for controllably changing the spot size in laser engraving, and also US Pat. No. 5,637,244, which depicts various three-dimensional structures that can be attached inside a transparent material body.

The previous documents on laser engraving are either concerned with capturing information in the transparent material body or generally defining three-dimensional structures. However, these known procedures are not used specifically to To introduce inhomogeneities or scattering centers in a scattering body in connection with an optical light scattering unit. In this context, it has proven useful if the inhomogeneities or scattering centers are designed as laser markings, that is, they are introduced into the transparent scattering body with the aid of a laser. As a rule, electromagnetic radiation is used in the near infrared, in the visible or even in the UV range. For example, a Nd: YAG laser with a wavelength of 1, 064 microns or even one of 532 nm may be used. Basically, wavelengths of 355 nm or even 266 nm can be realized at this point. Alternatively, the inhomogeneities in question can also be generated with the aid of a CO ₂ laser.

The Nd aforementioned first: YAG lasers emit laser pulses with a pulse duration of no more than ^{10 -6} sec duration, in particular even pulse durations of 10 to ^'8 seconds or less generated. As a result, it is possible to achieve power densities of more than 10 ⁷ W / cm ² and to realize the previously mentioned energy densities of several J / cm ² . For (XVLaser) these output powers are up to about 20 kW available and operated both continuously and pulsed In this connection, similar power densities can be generated as described above.The output wavelength is about 10.6 in the mid-infrared μm, occasionally even at 9.4 μm.

In contrast to the electromagnetic radiation source, which defines the inhomogeneities or scattering centers or in general structures inside the scattering body and emits in the infrared, visible or UV range, the light source operates continuously in the visible spectral range, ie transmits the light spectrum to be perceived by the human eye out. The wavelength range of the light source thus extends approximately from 380 nm to 750 nm. It is of course possible to work with a continuous light spectrum as well as with a discontinuous and of course also with a pulsed light spectrum emitting from the light source. is being done. The inhomogeneities or scattering centers usually have a size in the micrometer range.

As already explained, the inhomogeneities are advantageously designed as laser markings or laser structuring. These are introduced into the transparent scattering body or attached to its surface by selectively exceeding the damage threshold in the scattering body with the aid of the laser. As a result, the transparent scattering body, of course, remains permeable to the light spectrum emitted by the light source, only the light rays emitted by the light source are wholly or partially scattered at the inhomogeneities or scattering centers.

The design is usually made so that the inhomogeneities are distributed anisotropically in the interior of the scattering body. The anisotropy can be produced by the fact that the inhomogeneities describe a specific and given density and / or a specific and given topological structure. Of course, the individual inhomogeneities over the volume or the surface of the scattering body can of course have different densities. Also spatially different topological structures are conceivable. In this way, the inhomogeneities or scattering centers ensure that the incident light is anisotropically scattered in predetermined spatial directions. In other words, with the help of the inhomogeneities, it is possible on the output side of the transparent scattering body to specifically favor certain directions for the scattered light.

In addition to a homogeneous brightness distribution realized on the output side of the diffuser, it is thus also possible to control the light and deflect it anisotropically in certain spatial directions. Depending on the structure incorporated in the scattering bodies, geometrical patterns can also be realized.

The light scattered by the inhomogeneities and emerging from the scattering body defines a specific spatial scattered light distribution. This depends on the size of the inhomogeneities or scattering centers, their density and their spatial extent and finally their spatial orientation. In principle, it is also possible to work with differently large inhomogeneities in one and the same scattering body. In this context, it has proven useful in a method for producing such an optical light scattering unit, first of all, to introduce into the transparent scattering body by means of the electromagnetic radiation, preferably laser radiation, the surface markings and / or sub-surface markings. In addition, the emitted light from the light source is coupled into the scattering body produced in this way. The size and / or density and / or spatial extent of the inhomogeneities or scattering centers are now the spatial scattered light distribution outside of the scattering body before.

In the context of the invention, the procedure can advantageously be such that the size and / or density and / or spatial extent of the said inhomogeneities or scattering centers is set in accordance with a desired spatial scattered light distribution during the production process, for example in the sense of a control. In this case, the procedure is such that the light source is coupled into the scattering body, even during the production process. That is to say, the light coupled in and emitted by the light source is scattered during the introduction of the surface markings and / or sub-surface markings thereon already during the production process. By now recording the spatial scattered light distribution during production, the production process can be controlled such that at its end the scattering body generates the previously desired spatial scattered light distribution of the coupled-in light.

In this context, it is recommended, for example, to record the spatial scattered light distribution generated on the output side of the scattering body by means of, for example, imaging methods. For this purpose, one or more cameras, photodiodes, etc. may be used. In any case, during the manufacturing process of the scattering body or when introducing the inhomogeneities with the aid of the electromagnetic radiation or preferably the laser radiation as it were observed in situ their scattering effect and detected. In which now the actual measured spatial scattered light distribution is compared with a desired predetermined spatial scattered light distribution, the electromagnetic radiation source or the laser can be performed accordingly to obtain the predetermined spatial scattered light distribution. This usually happens in the sense of a regulation. As a result, the scattering body and with it the optical light scattering unit in the course of the manufacturing process can be precisely adapted to the later intended use and in particular the spatial scattered light distribution desired in this context.

It is understood in this context that regularly the light source used, the emitted light is coupled into the scattering body and scattered in its passage to the inhomogeneities present in the interior, is maintained for the subsequent purpose. Basically, however, an exchange is possible. Likewise, it has proven useful if the light source in question or the plurality of light sources are operated, for example, independently of the scattering body before the inhomogeneities are applied, for example, to set aging-related brightness changes as low as possible during the subsequent service life. This applies in particular to the case that LEDs and here especially white light LEDs are used as one light source or multiple light sources. Either way, the optical light scattering unit according to the invention or the transparent scattering body used can be specifically adapted to the subsequent intended use with regard to its generated spatial scattered light distribution during the production process.

It is conceivable, for example, to scatter the light irradiated by the light source with the aid of the inhomogeneities or scattering centers such that circles, lamellas, lines, squares or other shapes and structures with or without a creative effect emerge on the exit side of the transparent scattering body on a projection surface let realize. At each pursued technical This does not change the effect and the physical connections.

Overall, it has been proven that the transparent scattering body is flat and designed as a scattering plate. In any case, prior to introduction of the inhomogeneities, the scattering body has a closed and smooth surface, which in particular has no microstructuring, as is known from the prior art. As a result, the surface is easy to clean and at the same time insensitive to dirt, which is particularly important for outdoor use is of particular importance. This property is especially observed when only sub-surface markings are created inside.

As a rule, the light source or the light emitted by it and the scattered light have a substantially coincident direction, wherein the scattering body is interposed between the light source and the scattered light. This substantially coincident direction is due to the fact that the light emitted by the light source and coupled into the scattering body is predominantly elastically scattered in the forward direction at the inhomogeneities. In addition, one observes alternatively or additionally reflections on the inhomogeneities.

In this connection, the scattering body can also be advantageously used as a projection surface. This is among other things favorable for the realization of displays, display units etc. In this case, the light source is advantageously designed as a projector and the scattering body as the already mentioned projection surface. An image generated by the light source or the projector can be made visible in this way in the interior or, in principle, also on the surface of the diffuser by the inhomogeneities or scattering centers present there. The scattering body acts in this context as a projection surface, but in principle also spatial representations are conceivable, so that the scattering body in this case represents a projection space. In principle, however, it is also possible for the light source and the scattered light to be arranged at an angle to one another. For example, a rectangular or nearly rectangular arrangement of the light source and the scattered light is conceivable and is encompassed by the invention. In this case, the light source can be coupled via an edge in the (area) diffuser.

Of particular and independent significance for the invention is furthermore the fact that the inhomogeneities in the interior and / or on the surface of the scattering body can have a varying density. In this way, for example, the light propagation can be limited. Thus, it is conceivable that the incident light of the light source is scattered, for example, only between previously introduced clusters of inhomogeneities. Also, this can limit the direction of light propagation. As a result, for example, reflections can be avoided if the optical light scattering unit is used as a display or general display unit. In addition, the varying density and / or size and / or orientation of the inhomogeneities in the scattering body can be used to counteract a weakening of the light beams by scattering. That is, by these measures, the decreasing light intensity can be counteracted by scattering and / or reflection.

It is also possible to use the inhomogeneities specifically for this purpose and to introduce them into the scattering body in order to counteract absorption of the incident light in the material of the scattering body. This absorption can be caused, for example, by a turbidity of the material. In any case, it is possible to counteract, for example, the varying density of the inhomogeneities by compensating for the decreasing light intensity when passing through the scattering body or at the exit from it.

In fact, as the length of their travel within the scattering body increases, the light rays are more and more deflected by the inhomogeneities. Basically, an increasing absorption is conceivable. However, most of the scattering body is made transparent throughout, so that the decrease in Light intensity is due to the increased scattering of the inhomogeneities with increasing path of the light beam through the scattering body scattering. This decreasing light intensity can be accommodated by increased scattering with increasing distance from the light source. This increased scattering can be produced by an increasing density of the scattering centers and thus inhomogeneities in the transparent scattering body.

As a result, it is advantageous in this context if the density of the inhomogeneities or scattering centers in the transparent scattering body increases with increasing distance from the light source. In this way, for example, a decreasing light intensity and consequently decreasing brightness in the interior of the scattering body can be counteracted by compensating in whole or in part for this decreasing brightness through an increasing number of scattering centers. The result is a scattering body or a scattering plate with homogeneous light emission, even if the light source is coupled via an edge.

As materials for the scattering body used, the invention recommends glasses, such as mineral glasses or plastics, such as. As acrylic glass, polycarbonate, PVC, PET, etc. In addition, solid-state crystals such as sapphire, quartz, etc. may be used. What is decisive is solely the property of the materials used to be transparent to the light spectrum emitted by the light source and, moreover, to be able to permanently define markings by laser engraving and / or laser surface engraving or the like. In addition, the interpretation will be made in such a way that the markings or structures are present as bubbles, crack stars, indentations or depressions. These structures lead macroscopically to a clouding of the material or to a lens effect in the affected area, although the material of the scattered body between the individual structures naturally remains transparent and undergoes no turbidity or a lens effect. Finally, the invention also proposes that the scattering body is designed to be reflective at least on one side or on both sides. This can be done by, for example, by depositing a reflective layer on a surface of the diffuser, by adhering such a layer, or by imparting a pattern to a reflective layer at a distance from the relevant surface. Alternatively, however, it is also possible to work with mirror glass from the outset, ie a glass body or a glass pane which already has an applied mirror layer on at least one side. The mirror layer may be formed as a vapor-deposited aluminum layer. In any case, the scattered light is further directed and undergoes a spatial guidance.

In this case, the inhomogeneities in the scattering body can be arranged so that overall a geometric body is described. This geometric body may be circles, spirals, slats, lines, squares, letters, numbers, characters, logos, etc. With the help of the shape and size of these structures not only design effects can be achieved, but also the light coupled in via the light source can be guided.

The invention also relates to a surface radiator, which is characterized by an optical light scattering unit, which has the specifications described above. This surface radiator may be, for example, a display or a display unit, a lamp, wall elements, room elements such as room dividers, projection surfaces in the form of a glass screen, room or ceiling lighting, illuminated heat surfaces, etc. Most of the time you will realize surface spotlights that provide a homogeneous light emission available or with the help of a targeted light control is generated.

The invention also relates to the use of an electromagnetic radiation source for generating surface markings and / or sub-surface markings in a transparent scattering body in the course of Use of this scattering body in conjunction with a light source whose emitted light is coupled into the scattering body and scattered as it passes through the inhomogeneities thus generated and present in the interior to realize an optical light scattering unit.

As a result, an optical light scattering unit and a surface radiator are described, which can be adapted particularly cost-effective, quickly and efficiently to the specific requirements. This is due in particular to the fact that the inhomogeneities or scattering centers ultimately responsible for the light guidance inside the transparent scattering body can be specified virtually arbitrarily in terms of size, shape and arrangement (size and / or density and / or spatial extent). After all, the scattering centers or inhomogeneities in question are advantageously introduced by means of a laser beam into the scattering body in question, which selectively crosses the source of destruction in the scattering body.

By either the laser beam is moved two-dimensionally and / or three-dimensionally and / or the scattering body undergoes a two-dimensional and / or three-dimensional movement, any spatial structures in the interior and / or on the surface of the scattering body can be defined. As a result, the light coupled into the scattering body and emitted by the light source is deflected in the desired directions at the scattering centers. Here are the main benefits.

In the following the invention will be explained in more detail with reference to a drawing showing only one exemplary embodiment; show it:

1 and 2, two different embodiments of an optical light scattering unit or a surface radiator, which operates in accordance with the invention,

3 and 4 modified embodiments according to the invention, Fig. 5 A, B, the embodiments of FIGS. 3 and 4 schematically in plan and again each different design and

FIG. 5C shows a diagram of the intensity distribution of the scattered light intensity, taking into account a scattering element according to FIG. 5 B. FIG.

FIGS. 1 and 2 show an optical light scattering unit which, in its basic structure, has a transparent scattering body 1 and at least one light source 2. The optical light scattering unit with the diffuser 1 and the light source 2 may be part of a surface radiator, which can be realized in this way. This becomes clear in particular with reference to FIG. 2. Because for a viewer B, the optical light scattering unit appears as if the entire transparent scattering body 1 is illuminated flat, for example, emits a uniform homogeneous light intensity.

In this context, the scattering body 1 in the variant of FIG. 2 also act as a projection surface or represent such. Then the light source 2 may be designed as a projector 2. The light source or the projector 2 projects an image which appears in the interior or on the surface of the scattering body 1 as an associated projection surface. Such an approach can be implemented to define, for example, a display, a display unit, etc.

In order to achieve this in detail, the light emitted by the light source 2 is coupled into the scattering body 1. In the variant according to FIG. 2, this can take place in such a way that the light emitted by the light source 2 enters the diffuser 1 in a rear surface 1a and out of the opposite front surface 1b again after the scattering of inhomogeneities 3 in the interior of the diffuser 1 exit. In addition or as an alternative thereto, however, it is also possible that the light entry does not take place via the wide sides 1a, 1b previously referred to in the scattering body 1 which is in the form of a scattering plate or cuboid scattering plate, but rather over its narrow sides 1c or 1d. Then, after scattering the coupled-in light at the inhomogeneities or scattering centers 3 in the interior of the scattering body 1, a light exit via the two broad sides 1a, 1b or the back surface 1a and the front surface 1b, as shown by way of example in FIG ,

In the context of the alternative according to FIG. 2, a conventional thermal radiator or a suitable white light source is used as the light source 2. In contrast, the light source 2 according to FIG. 1 is one or more punctiform radiators, for example an LED, which may also emit colored light. Either way, the spectrum emitted by the light source 2 completely or partially covers the light spectrum, ie the visible region.

The inhomogeneities or scattering centers 3 in the interior and / or on the surface of the scattering body 1 are introduced in the course of internal machining and / or surface processing, which takes place with the aid of a laser, for example an Nd: YAG laser or CO ₂ laser. In this process, the inhomogeneities or laser markings 3 are generated in such a way that with the aid of the laser beam the damage threshold in the scattering body 1 or at its surface is selectively exceeded. For this purpose, the laser beam undergoes a corresponding focusing, so that there is the so-called dielectric breakdown and ionization. As a consequence thereof, the scattering body 1 is locally melted and substantially macroscopically visible bubbles or structures are formed, which are often additionally characterized by cracks protruding from their surface, in other words so-called crack stars. These structures have a size in the micrometer range and act altogether as scattering centers 3. This applies in any case for inhomogeneities or scattering centers 3, which are arranged completely inside the scattering body.

In principle, however, the inhomogeneities or scattering centers 3 may also be partially present in the interior of the scattering body 1 and open, for example, to the surface. Then the inhomogeneities or scattering centers are 3 Usually formed as recesses or depressions and have a smooth-walled surface. Also in this case, inhomogeneities or scattering centers 3 in the interior of the scattering body 1 the speech, but with an opening 3a and a molding 3b, as shown in Fig. 3 in detail.

The scattering centers or inhomogeneities 3 ensure that the light 4 emitted or emitted by the light source 2 is scattered thereon predominantly in the forward direction in the context of the illustration according to FIG. 2 and leaves the scattering body 1 as scattered light 5. In this variant, the scattering body 1 - as described - act as a projection surface for the projector 2 leaving image. In principle, a spatial representation in the scattering body 1 is conceivable. Then the scattering body 1 acts as a projection space.

By contrast, FIG. 1 shows an angular scattering with scattering angles in the range of 90 ° or more. In this case, the inhomogeneities 3 can also scatter the irradiated light anisotropically in predetermined spatial directions if the inhomogeneities 3 have a specific structure in the interior of the scattering body 1 or on its surface, as has already been described in the introduction.

The diffuser 3 has in the examples according to FIGS. 1 and 2 in total a closed and smooth surface, because the inhomogeneities or scattering centers 3 are arranged completely in the interior of the scattering body 1 and the described internal laser engraving does not damage the surface. As a result, the surface is easy to clean and does not tend to stain. As a result, the illustrated optical light scattering unit or a surface radiator realized thereby is predestined for outdoor use. For example, it is not difficult to realize a display unit or a display with the aid of the light scattering unit. It is also possible to produce lamps, wall elements, etc.

The scattering body 1 can be made of the previously described materials such as glass, plastic or crystalline materials and mixtures become. For example, it is conceivable to manufacture the scattering body 1 as a scattering plate or diffuser made of, for example, acrylic glass, glass, PVC, PET.

In the variant according to FIG. 2, the light source 2 and the light 4 emitted by it, as well as the scattered light 5, have a substantially coincident direction, the scattering body or the scattering plate or diffusing screen 1 being interposed. In contrast, Fig. 1 follows a variant in which the light source 2 and the emitted light 4 and the scattered light 5 at an angle, z. B. predominantly rectangular, are arranged to each other. In this way, it is achieved that the light 4 entering the scattering body or the scattering disk 1 via the narrow side 1c emerges after the scattering at the inhomogeneities or scattering centers 3 on the two broad sides 1a and 1b and can also exit. An additional reflection layer 6 spaced from the diffusing screen 1 may ensure that the scattered light 5 exits primarily from the front surface 1b and undergoes a directed guidance to the right in the illustration in FIG.

Finally, FIG. 1 indicates that the inhomogeneities or scattering centers 3 can have a varying density in the interior of the scattering body 2. In fact, the design is such that the density of the inhomogeneities or scattering centers 3 increases with increasing distance from the light source 2. Alternatively or additionally, however, the size or shape of the scattering centers 3 can also change with increasing distance from the light source. In any case, in this way a growing scattering of the light 4 emitted or emitted by the light source 2 at the inhomogeneities or scattering centers 3 can be taken into account. Because of this fact, the brightness of the emitted light beams 4 in the interior of the scattering body 1 decreases with increasing distance from the light source 2.

In order to compensate for this effect or weaken it is worked with increasing distance from the light source 2 with a growing number of scattering centers 3. Alternatively or additionally, however, the size and / or shape of the scattering centers 3 can also be changed. As a result, will Even with the embodiment according to FIG. 1, with the light source 2 attached as it is laterally, the light intensity of the scattered light 5 across the exit surface 1a, 1b is essentially the same. D. h., Even in the variant of Fig. 1, a homogeneous surface radiator is ultimately provided.

Within the scope of the variant according to FIGS. 3 to 5, an optical light scattering unit is likewise shown which has differently designed scattering bodies 1 and at least one light source 2. In accordance with the example according to FIGS. 1 and 2, the inhomogeneities 3 are present unchanged in the interior of the diffuser 1, but in the present case and predominantly on its surface. That is, the inhomogeneities 3 have the already mentioned opening 3a to the surface. In this case, the design will be such that the inhomogeneities 3 with their indentation 3b extend into the interior of the scattering body 1, that is still present in the interior of the scattering body 1. In fact, the inhomogeneities 3 according to FIGS. 3 to 5 are material depressions which have been introduced into the surface of the scattering body 1 with the aid of the electromagnetic radiation. For this purpose, laser radiation is used again. Most of the time you will fall back on a CO ₂ laser in combination with a light deflection unit (for example, a galvanometer scanner). In principle, this light deflection unit can also be used in conjunction with the Nd: YAG laser already described.

In any case, the inhomogeneities in question 3, as shown in FIGS. 3 and 4, are found again in the interior of the diffuser 1, in the form of recesses which face the surface with their openings 3a, whereas the corresponding indentation 3b enters the interior of the diffuser body 1 has or is present in the interior. The openings 3a are, for example, formed on a longitudinal side or broad side 1a, 1b of the diffuser 1. Typically, the diameters of the openings 3a are in the range of 1 .mu.m to 500 .mu.m, preferably in the range of 5 .mu.m to 100 .mu.m. This depends on the focus diameter of the laser used below a down focusing lens. The depth of the indentation 3b may be a few microns up to a few mm.

Depending on the pattern of movement of the respective inhomogeneity 3 in the litter 1 inscribing laser or generally the electromagnetic radiation, quite different structures and forms of the respective inhomogeneity 3 can be defined. Thus, it is conceivable, for example, to be able to introduce punctiform formations, circles, squares, lines, triangles, characters, numbers, letters, logos, etc., as shown by way of example in FIG. 5A for individual differently formed inhomogeneities 3. In this way, the light emitted into the scattering body 1 and from the light source 2 can be coupled in quite different ways and scattered out of the scattering body 1.

In fact, the light 4 emitted by the light source 2 in the example cases according to FIGS. 3 and 4 enters a narrow side 1c or both narrow sides 1c, 1d of the diffuser 1. It is also possible for two light sources 2 to couple the correspondingly emitted light 4 into the diffuser 1 in question via the two opposite narrow sides 1c, 1d, as FIG. 4 shows.

In the interior of the scattering body 1, after the scattering of the coupled-in light 4 at the inhomogeneities or scattering centers 3, a light exit or the scattered light 5 occurs. If the inhomogeneities 3 are present, for example, on only one broad side 1a, then the coupled-in light 4 emerges predominantly on the other broad side 1b as scattered light 5, as FIG. 4 shows. This can essentially be attributed to the total reflection occurring inside the scattering body 1. Because the coupled-in light 4 runs zigzag between, for example, the two surfaces 1a and 1b and the associated plate surfaces of the scattering body 1 back and forth. In this way, the coupled-in light 4 can emerge completely or partially from the diffuser 1 not only on the broad side 1b, but also on the broad side 1a with the inhomogeneities 3 present there (see FIG. 4). However, as soon as the coupled-in light 4 strikes the respective inhomogeneity 3, depending on the design of the inhomogeneity 3, the light 4 is reflected thereon in such a way that it leaves the scattering body 1, for example, on the opposite surface 1b. Because then the angle condition for total reflection is no longer respected.

It is clear from the plan view according to FIG. 5B that the density of the inhomogeneities or scattering centers 3 can change as seen over the surface of the scattering body 1. In addition, in the context of the example according to FIG. 5A, different structures of the respective inhomogeneities 3 are used. In this way, the inhomogeneities 3 can be arranged distributed anisotropically in the interior of the scattering body 1 or on its surface. In this case, it is usually possible to change both the density and the topological structure of the individual scattering centers or inhomogeneities 3. This also applies to their spatial orientation.

Of course, the depth of the indentation 3b, as well as the shape of the inhomogeneity 3 as a whole, can undergo a change. These various possibilities are shown in FIGS. 5A and 5B. FIG. 5C now describes a diagram of the intensity distribution of the light I (X, Y) emerging from the scattering body 1 in accordance with FIG. 5B.

On the basis of this sketch 5C it can be seen that, depending on the orientation of the inhomogeneities or scattering centers 3, the light in the example case according to FIG. 5B is mainly scattered and reflected in the direction X, but less in the direction Y. This is due to the orientation of the linear inhomogeneities 3 achieved in the illustrated example of FIG. 5B, which extend in the Y direction.

In fact, these are linear inhomogeneities 3 introduced in the area of the surface or the surface 1a of the diffuser 1 in the arrangement and distribution according to FIG. 5B. Once from the two light sources 2 light 4 coupled into the scattering body 1 via the narrow sides 1c or 1d, the light 4 in question and coupled in is preferably scattered and reflected in the direction X. On the other hand, scattering and reflection in direction Y are less or not at all observed. In this way, an angle-dependent light emission can be generated and used, for example, to avoid unwanted glare or reflections. This is for applications of the scatter body 1 as a display of particular importance.

The length of the arrows according to the sketch according to FIG. 5C stands for the intensity of the light intensity I (X, Y) in the indicated direction X or Y. It can be seen that more light is passed through the scatter body 1 in the X direction and this leaves as in the Y direction. For intermediate angles, a corresponding transition is observed. This indicates the respective intensity dependent on the direction I (X, Y) in FIG. 5C. The coupled-in light 4 enters the scatter body 1 or its narrow sides 1c, 1d in the X direction. Following this, the coupled-in light 4 is partially scattered or reflected at the inhomogeneities 3 and leaves the scattering body 1 via its broad sides 1a, 1b as scattered light 5 in the Y direction.

The length of the arrows in the sketch according to FIG. 5C stands for the intensity of the light intensity in the indicated direction X or Y. It can be seen that more light is guided through the diffuser 1 in the X direction than in the Y direction. For intermediate angles, a corresponding transition is observed. This indicates the respective intensity-dependent intensity I (X, Y) in FIG. 5C. The coupled-in light 4 enters the scatter body 1 or its narrow sides 1c, 1d in the X direction. Following this, the coupled-in light 4 is partially scattered or reflected at the inhomogeneities and leaves the scattering body 1 via its broad sides 1a, 1b as scattered light 5 in the vertical direction or Y-direction. However, since only a more or less small part of the light is scattered, it can be explained that the light intensity I (X, Y) in the X-direction is greater than that in the Y-direction. As a material for the scattering body 1, in principle, transparent materials are recommended, ie those which are continuous for the light emitted, for example, by LEDs. These are by way of example and not restrictive to glass, plastic, such as polycarbonate, etc. Of course, the scattering body 1 can also be colored. In addition to LEDs as light source 2 and OLEDs, fluorescent tubes or similar light sources 2 can be used.

Quite apart from that, the described scattering body 1 can be combined with a mirror or a mirror-like structure. In this case, the inhomogeneities 3 can be introduced either on a reflective side or on the opposite side or on both sides. D. h., Taking into account the embodiment of FIG. 3 can be applied to the surface 1 a, on the surface 1 b or on both surfaces 1 a, 1 b, a reflective surface. If the structure or the inhomogeneities 3 are introduced into the scattering body 1 before the deposition or vapor deposition of the reflecting layer, they can be mirrored with it. As a result, a particularly intense light scattering and reflection will be observed. In this way, mirrors produced in this way can be illuminated via, for example, the narrow sides 1c and / or 1d. As a result, the light intensity exiting the unstructured and uncoated surface 1b is high. As a result, mirrors with integrated lighting can be realized by laterally coupled-in light.

Another possibility is to equip displays, gauges or general screens or monitors with a homogeneous illumination of the background. In this case, the light is coupled via, for example, the two surfaces or narrow sides 1c and 1d in a transparent surface light guide behind an associated display. This can be done via one or more LEDs. The surface light guide is a diffusion plate of the structure described. Since such surface light guides usually have a considerable extent, it is advisable to vary the density of the inhomogeneities 3. For example, the density of the inhomogeneities 3 or scattering centers 3 may increase with the distance from the associated light source 2 because the light intensity decreases exponentially with a greater distance from the light source 2. Mostly one will encounter this with an exponential increase in the density of the inhomogeneities 3 or scattering centers 3 as a function of the distance to the light source 2. Alternatively or additionally, the size and / or structure and / or depth of the respective inhomogeneities or scattering centers 3 can be changed as a function of the distance to the light source 2 such that the scattered light increases with the distance from the light source 2, and also exponentially , As a result, a homogeneous light extraction can be realized in summary. The area illuminated in this way appears uniformly bright, although the light is coupled in only on one side, for example via the side 1c or via both sides 1c, 1d. Such a situation is illustrated in FIG. 5B.

It can be seen from FIG. 5B that the density of the inhomogeneities 3 increases exponentially with increasing distance from the light source 2 and is maximal in the central region of the scattering body 1. In the present case, two opposing light sources 2 are used, which are respectively coupled into the opposite narrow sides 1c, 1d.

Claims

claims

1. Optical light scattering unit, with a transparent scattering body (1), and with at least one light source (2) whose emitted light (4) coupled into the scattering body (1) and scattered in its passage to inhomogeneities present in the interior (3) is, characterized in that the inhomogeneities (3) as by electromagnetic radiation in the scattering body (1) introduced surface markings and / or sub-surface markings are formed.

2. Optical light scattering unit according to claim 1, characterized in that the inhomogeneities (3) are designed as laser markings, which are introduced by means of a the damage threshold in the scattering body (1) punctually crossing laser beam.

3. Optical light scattering unit according to claim 1 or 2, characterized in that the inhomogeneities (3) scatter the incident light (4) anisotropically in predetermined spatial directions.

4. Optical light scattering unit according to claim 3, characterized in that the inhomogeneities (3) in the interior of the scattering body (1) describe a predetermined density and / or topological structure.

5. Optical light scattering unit according to one of claims 1 to 4, characterized in that the transparent scattering body (1) as a scattering plate (1) is formed.

6. Optical light scattering unit according to one of claims 1 to 5, characterized in that the of the light source (2) emitted light (4) and the scattered light (5) have a substantially coincident direction, wherein preferably the light source (2) as Projector (2) and the scattering body (1) are designed as a projection surface.

7. Optical light scattering unit according to one of claims 1 to 6, characterized in that the emitted light (4) and the scattered light (5) are arranged at an angle, predominantly rectangular, to each other.

8. Optical light scattering unit according to one of claims 1 to 7, characterized in that the emitted light (4) via at least one edge (1c, 1d) is coupled into the scattering body (1).

9. Optical light scattering unit according to one of claims 1 to 8, characterized in that the inhomogeneities (3) have a varying density in the

Have inside the scattering body (1).

10. Optical light scattering unit according to claim 9, characterized in that the density of the inhomogeneities (3) with increasing distance from the light source (2), for example, increases exponentially to compensate for increasing scattering of the emitted light (4) in whole or in part.

11. Optical light scattering unit according to one of claims 1 to 10, characterized in that the scattering body (1) is made of a glass, plastic or a crystalline transparent material.

12. Optical light scattering unit according to one of claims 1 to 11, characterized in that the scattering body (1) is designed to be reflective at least on one side and / or the scattering body (1) at least one reflective surface (6) is associated.

13. Optical light scattering unit according to one of claims 1 to 12, characterized in that the inhomogeneities (3) describe a geometric body or numbers, letters, characters, logos, etc.

14. A method for producing an optical light scattering unit, according to which surface markings and / or sub-surface markings for producing a transparent scattering body (1) by means of electromagnetic radiation are used. In addition, emitted light (4) of a light source (2) is coupled into the scattering body (1), and then the size and / or density and / or spatial extent of the generated inhomogeneities (3) Given a desired spatial scattered light distribution outside of the scattering body (1) is set during the process or production process in terms of a scheme.

15. Area radiator, characterized by an optical light scattering unit according to one of claims 1 to 13.