DE102021127448A1 - LIDAR assembly and method of coating a lens of a LIDAR assembly - Google Patents

Abstract

The invention relates to a LIDAR assembly (2) for a motor vehicle, which has at least two light components (s1, s2, s3) and a transparent cover pane (4), through which the light beams of the light component (s1, s2, s3) pass through, with the light components (s1, s2, s3) having optical axes (5, 6, 8) which are skewed or at an angle to one another, with only a single anti-reflection coating (10) with different layer thicknesses on the cover pane (4). (d1, d2, d3) is provided.

Description

According to patent claim 1, the invention relates to a LIDAR assembly for a motor vehicle. According to patent claim 7, the invention also relates to a method for coating a cover pane of a LIDAR assembly.

Out of EP 0 533 044 81 discloses a method for the protective coating of a metallized headlight reflector by means of plasma polymerisation with at least one gaseous organosilicon compound. In the process, a plasma is generated in a vacuum chamber by means of a DC-free electromagnetic alternating field. A gas is supplied with the anti-reflection coating forming compound. Periodic amplitude modulation of the alternating field largely prevents the formation of powdery components on the protective layer.

Furthermore, in the field of motor vehicles, distance determination by means of LIDAR is known, in which two light components are provided. One light component is a transmitter unit and the other light component is a receiver unit. The transmission unit has a LIDAR emitter with which a laser beam can be emitted. The laser beam is guided through the transparent cover pane and reflected or scattered outside the motor vehicle by object surfaces that lie in the beam path of the laser beam. The receiver unit detects the laser beam so that the distance to the object surface can be determined from the transit time of the laser beam.

The object of the invention is to create a LIDAR assembly with multiple light components that can be positioned relatively freely behind a transparent cover pane without the quality of the distance determination suffering from the positioning of the light component. It is also an object of the invention to create a method for coating a transparent cover panel of a LIDAR assembly in such a way that several light components can be positioned relatively freely behind the cover panel without the quality of the distance determination being affected by the positioning of the light component suffers.

According to the invention, in a LIDAR assembly for a motor vehicle, the LIDAR assembly has at least two light components and a transparent cover pane, through which the light beams of the light component pass, the light components having optical axes that are skewed or im Angles are to each other, with an anti-reflection coating is provided with different layer thicknesses on the cover plate. Due to the difference in the layer thicknesses of the anti-reflection coating, the layer thicknesses can be dimensioned in such a way that the transmittance is optimized for the respective light incidence angles of the light components.

In order not to negatively influence the transmittance through other coatings and in order not to damage the anti-reflection coating through other chemical and/or thermal coating processes, it can be provided that only the one anti-reflection coating is provided on the cover pane, which in this respect represents the only coating of the cover pane.

The anti-reflective coating preferably comprises hexamethyldisiloxane, also referred to as HMDSO. HMDSO has good thermal properties and is an optically effective medium in combination with organic glasses. In this respect, the cover plate can preferably consist of polycarbonate.

So that the antireflection coating is particularly effective, it can be arranged on the side of the cover pane facing the light component.

The light components can be two or three laser transmitter units or laser receiver units. It is also possible to arrange one or more LIDAR modules behind the cover pane, each of which has both a laser transmitter unit and a laser receiver unit. In this respect it can be provided that the light beams are laser beams. Furthermore, the antireflection coating can be optimized with regard to a degree of transmission of the laser beams. The layer thicknesses of the anti-reflection coating are defined as a function of the angles of incidence of the laser beams on the cover pane.

However, it is also possible that one of the light components emits visible light to illuminate the roadway or for display (rear light, parking light, indicator light). Visible light is also better transmitted as a result of the anti-reflection coating. This applies in particular if the said light component for visible light is combined with an infrared laser transmitter unit of a LIDAR.

berechnet sind,

• - wobei α₀ ein optimierter Transmissionswinkel der Laserstrahlen ist, der sich als gewichtetes arithmetisches Mittel einzelner Einfallswinkel α ergibt, mit denen Strahlenbündel quasi-kollimierter Laserstrahlen der Licht-Komponenten auf den jeweils betrachteten Teilbereich auftreffen,
• - wobei λ die Wellenlänge der Laserstrahlen ist,
• - wobei n₁ die Brechzahl des Materials der Antireflexionsbeschichtung ist und
• - wobei n₀ die Brechzahl von Luft ist.

The layer thickness d of individual sub-areas of the anti-reflection coating can be calculated particularly advantageously at different points on the cover pane by changing the layer thickness d of the anti-reflection coating on the individual sub-areas of the anti-reflection coating tion distinguishes at least two sub-areas according to the formula $$\mathrm{i.e}=\frac{\mathrm{<figure-callout\; id="4"\; label="\lambda "\; filenames="DE102021127448A1\_0008.png,DE102021127448A1\_0009.png"\; state="\{\{state\}\}">\lambda </figure-callout>}}{4}\cdot \frac{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DE102021127448A1\_0011.png"\; state="\{\{state\}\}">n</figure-callout>}}_1\text{cos}({\text{sin}}^{-1}\left(\text{sin}{\propto }_0\cdot \frac{n_0}{n_1}\right))}{si{n}^2\left(a_0\right)-{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DE102021127448A1\_0011.png"\; state="\{\{state\}\}">n</figure-callout>}}_1{}^2}$$

are calculated

• - where α ₀ is an optimized transmission angle of the laser beams, which results from the weighted arithmetic mean of individual angles of incidence α, with which bundles of rays of quasi-collimated laser beams of the light components impinge on the respective partial area under consideration,
• - where λ is the wavelength of the laser beams,
• - where n ₁ is the refractive index of the material of the anti-reflection coating and
• - where n ₀ is the refractive index of air.

The refractive index of air is relevant since air is preferably arranged between the light component and the cover pane. The layer thickness of the anti-reflection coating on the cover pane is thus dynamically distributed according to the average sum of the angles of incidence of the light components.

• - die Abdeckscheibe und eine bewegliche Schablone so zueinander positioniert werden, dass die Schablone zwischen der Abdeckscheibe und einem Emitter für ein Material der Antireflexionsbeschichtung angeordnet ist,
• - in einem ersten Beschichtungsschritt vom Emitter das Material emittiert wird und anschließend gasförmig durch zumindest eine erste Ausnehmung der Schablone geleitet wird und als ein erster Teilbereich der Antireflexionsbeschichtung auf der Abdeckscheibe abgeschieden wird,
• - eine weitere Ausnehmung, die hinsichtlich der Form und/oder Größe von der ersten Ausnehmung der Schablone abweicht, zwischen der Abdeckscheibe und dem Emitter positioniert wird, und
• - in einem weiteren Beschichtungsschritt vom Emitter das Material emittiert wird und anschließend gasförmig durch zumindest die weitere Ausnehmung geleitet wird und auf der Abdeckscheibe als ein weiterer Teilbereich abgeschieden wird, der zumindest teilweise mit dem ersten Teilbereich überlappt und/oder einen zuvor unbeschichteten Oberflächenbereich der Abdeckscheibe bedeckt.

In a method according to the invention for coating a cover plate of a LIDAR assembly, it is provided that

• - the cover plate and a movable stencil are positioned relative to one another in such a way that the stencil is arranged between the cover plate and an emitter for a material of the anti-reflection coating,
• - In a first coating step, the material is emitted by the emitter and is then conducted in gaseous form through at least a first recess in the stencil and is deposited on the cover pane as a first partial area of the anti-reflection coating,
• - a further recess, which differs in shape and/or size from the first recess of the template, is positioned between the cover disk and the emitter, and
• - In a further coating step, the material is emitted by the emitter and is then conducted in gaseous form through at least the further recess and is deposited on the cover pane as a further sub-area which at least partially overlaps with the first sub-area and/or covers a previously uncoated surface area of the cover pane .

In order to enable a quick change between the coating steps, provision can be made for the first and the further recess to be arranged on a common template and for the template to be moved for a change between the coating steps.

In order to enable an even faster change between the coating steps, it can be provided that the stencil is partially wound onto a roll and/or partially unwound from a roll when changing the recess.

Advantageously compared to plasma polymerisation, in which a gas forms the starting material for a plasma, it can be provided that the emitter is a solid body which is heated in order to emit the gaseous material for the anti-reflection coating.

In order to influence the layer thicknesses and the transitions of the partial areas of the coating, it can advantageously be provided that a coating parameter is changed between the first and the second coating step, with this coating parameter being the coating time and/or the distance between the stencil and the cover pane .

Further features, possible applications and advantages of the invention result from the following description of exemplary embodiments of the invention, which are explained with reference to the drawing.

• 1 schematisch eine LIDAR-Baugruppe in einem Schnitt entlang einer Horizontalebene eines Kraftfahrzeugs, wobei die LIDAR-Baugruppe eine Abdeckscheibe und drei Licht-Komponenten umfasst,
• 2 Teile der LIDAR-Baugruppe aus 1, wobei zusätzlich ein Lichtkegel der ersten Licht-Komponente dargestellt ist,
• 3 eine Darstellung analog zu 2, wobei ein Lichtkegel der zweiten Licht-Komponente dargestellt ist,
• 4 eine Darstellung analog zu 2 und 3, wobei ein Lichtkegel der dritten Licht-Komponente dargestellt ist,
• 5 bis 7 in Darstellungen analog zu 2 bis 4 die Abdeckscheibe mit verschiedenen Teilbereichen einer Antireflexionsbeschichtung, auf die quasi-kollimierte Strahlenbündel der Licht-Komponenten in Einfallswinkeln auftreffen,
• 8 ein Diagramm, in dem der Transmissionsgrad in Abhängigkeit vom Einfallswinkel dargestellt ist,
• 9 die Abdeckscheibe mit der Antireflexionsbeschichtung und Formelbuchstaben,
• 10 eine Tabelle, in der dem Einfallswinkel Gewichtungsfaktoren zugeordnet sind,
• 11 eine Tabelle zur Verdeutlichung der Berechnung eines optimierten Transmissionswinkels aus dem gewichteten arithmetischen Mittel der einzelnen Einfallswinkel der Strahlenbündel,
• 12 in einer perspektivischen Ansicht eine bewegbare Schablone, und
• 13 bis 19 schematisch eine Vorrichtung zur Durchführung eines Verfahrens zur Beschichtung einer Abdeckscheibe nach 1 bis 11.

Show it:

• 1 schematically a LIDAR assembly in a section along a horizontal plane of a motor vehicle, the LIDAR assembly comprising a cover panel and three light components,
• 2 parts of the lidar assembly 1 , whereby a light cone of the first light component is also shown,
• 3 a representation analogous to 2 , where a light cone of the second light component is shown,
• 4 a representation analogous to 2 and 3 , where a light cone of the third light component is shown,
• 5 until 7 in representations analogous to 2 until 4 the cover pane with various sections of an anti-reflection coating onto which quasi-collimated rays bundles of light components impinge at angles of incidence,
• 8th a diagram in which the transmittance is shown as a function of the angle of incidence,
• 9 the cover plate with the anti-reflection coating and formula letters,
• 10 a table in which weighting factors are assigned to the angle of incidence,
• 11 a table to clarify the calculation of an optimized transmission angle from the weighted arithmetic mean of the individual angles of incidence of the beam of rays,
• 12 a movable template in a perspective view, and
• 13 until 19 schematically shows a device for carrying out a method for coating a cover plate 1 until 11 .

1 shows a LIDAR assembly 2 for a motor vehicle. The LIDAR assembly 2 can in particular be a headlight module or a rear light module and in this respect can be attached to the front or the rear of a motor vehicle.

In the exemplary embodiment, the LIDAR assembly 2 has three light components s 1 , s 2 , s 3 , which are arranged within a housing 3 that is covered by a transparent cover plate 4 . In the idealized representation, the cover plate 4 is shown in a planar plane. In the case of a LIDAR assembly 2 implemented on the motor vehicle, the cover pane has a complex spatial curvature.

The three light components s1, s2, s3 are preferably designed as LIDAR components. However, at least one of the light components could also be in the form of a low beam and/or a high beam and/or a rear light and/or a reversing light and/or a brake light and/or a turn signal and/or a matrix headlight.

Light components s1, s2, s3 have lenses that are not shown in more detail in the drawing, so that each of the light components s1, s2, s3 is assigned an optical axis 5, 6, or 8, respectively. The light components s1, s2, s3 are part of individual modules that include a transmitter unit and a receiver unit. The transmission unit has a LIDAR emitter and a lens. The receiver unit for the laser beam has a sensor and an objective.

The laser beam can be emitted with the transmission unit of the respective individual module, the wavelength of which is in the infrared light range, in the near infrared light range (NIR) or in the ultraviolet range. The laser beam is passed through the transparent cover plate 4 and out of the housing and is reflected or scattered outside of the motor vehicle by surfaces which lie in the beam path of the laser beam.

A portion of the laser beam reflected or scattered by the surfaces is directed through the cover plate 4 and into the LIDAR assembly 2 . The backscattered laser beam is detected with the receiver unit. The distance to the surface of the object from which the backscattered laser beam emanates is determined on the basis of the travel time of the laser beam. The LIDAR assembly and an associated electronic evaluation unit are thus used in the motor vehicle in order to recognize people and objects in the area surrounding the motor vehicle and to determine their distance. A three-dimensional image of the environment is calculated.

The optical axes 5, 6, 8 of the light components s1, s2, s3 are at an angle or skewed to one another. Thus, the optical axes 5, 6, 8 are neither parallel nor congruent to each other. In the example, the optical axes 5, 6, 8 are arranged symmetrically to one another with an angular offset of 45° in the horizontal plane, this horizontal plane relating to the installation position of the LIDAR assembly in the motor vehicle. However, the angular offset of the axes 5, 6, 8 relative to one another can also be asymmetrical in another exemplary embodiment.

• - die Brennweiten und Linsenabstände innerhalb des jeweiligen Objektivs,
• - der Öffnungsdurchmesser einer gegebenenfalls vorgesehenen Blende und
• - die geometrischen Abmessungen der jeweiligen Licht-Komponente s1, s2, s3.

Out of 2 until 4 It can be seen that the light components s1, s2, s3 have different optical opening cones k1, k2, k3, the cone axes of which are formed by the optical axes 5, 6, 8. The size of the optical aperture cone k1 or k2 or k3 is specified by a number of variables. These sizes include

• - the focal lengths and lens distances within the respective lens,
• - the opening diameter of an optional screen and
• - the geometric dimensions of the respective light component s1, s2, s3.

In the embodiment after 2 until 4 the aperture cones are k1=50°, k2=80° and k3=20°.

Out of 5 it can be seen that the cover plate 4 has an antireflection coating on the side facing the light components s1, s2, s3 device 10, which is the exclusive and only anti-reflective coating 10 on that side. That is, the anti-reflective coating 10 is a single layer coating. The anti-reflective coating 10 comprises hexamethyldisiloxane, which is abbreviated to "HMDSO". The cover plate 4 comprises an organic glass, which can be polycarbonate, for example.

5 until 7 show different randomly selected partial areas b21, b321, b1 of the anti-reflection coating 10.

Quasi-collimated laser beams of one or more of the light components s1, s2, s3 impinge on the antireflection coating 10 in the beam c1 or c2 or c3. Laser beams that are parallel to one another or have only a small angular deviation from one another in relation to the geometric arrangement of the system are referred to here as quasi-collimated laser beams.

Out of 5 it can be seen that both the first bundle of rays c1 of the first light component s1 and the second bundle of rays c2 of the second light component s2 impinge on the first partial area b21 of the antireflection coating 10 or the coated cover pane 4 .

• - sowohl das erste Strahlenbündel c1 der ersten Licht-Komponente s1
• - als auch das zweite Strahlenbündel c2 der zweiten Licht-Komponente s2
• - als auch das dritte Strahlenbündel c3 der dritten Licht-Komponente s3 auftrifft.

Out of 6 it can be seen that on the second partial area b321 of the anti-reflection coating 10 or the coated cover plate 4

• - Both the first bundle of rays c1 of the first light component s1
• - As well as the second bundle of rays c2 of the second light component s2
• - As well as the third bundle of rays c3 of the third light component s3 impinges.

Out of 7 it can be seen that the first bundle of rays c1 strikes the third partial region b1 of the antireflection coating 10 or the coated cover pane 4 with a relatively flat angle of incidence α. In contrast, the angle of incidence α of the first bundle of rays c1 on the first partial area b21 ( 5 ) and the second partial area b321 ( 6 ) steeper.

From a synopsis of 5 and 6 it can be seen that the angle of incidence α of the first bundle of rays c1 on the second partial area b321 ( 6 ) hits flatter than the first partial area b21 ( 5 ).

From the diagram after 8th it can be seen that the size of this angle of incidence α has an increasingly significant importance for the transmittance of the laser beam through the antireflection coating 10 from an excess of 40°. The transmittance of HMDSO on polycarbonate falls increasingly sharply at an angle of incidence α above 40° and is zero at an angle of incidence α=90°.

ist, wobei λ die Wellenlänge des zu transmittierenden Laserstrahls ist. Die Transmission ist hierbei abhängig vom Einfallswinkel α, da bei konstanter Schichtdicke die $\frac{\lambda }{4}-\text{Bedingung}$

nur dann erfüllt ist, wenn die Laserstrahlen orthogonal auf der Antireflexionsbeschichtung 10 auftreffen.In principle, ideal transmission takes place precisely when the layer thickness d of the anti-reflection coating is exact, taking into account the refractive index of the material of the anti-reflection coating $\frac{\lambda }{}$$\frac{}{4}$

where λ is the wavelength of the laser beam to be transmitted. The transmission is dependent on the angle of incidence α, since the layer thickness is constant $\frac{\lambda }{}$$\frac{}{4}-\text{Condition}$

is only satisfied if the laser beams strike the anti-reflection coating 10 orthogonally.

bei schrägem Einfall ergibt sich nach folgender Form: $$\frac{\lambda }{2}=n_1\left(w_1+w_{1r}\right)-n_0\cdot x$$

The fulfillment of $\frac{\mathrm{<figure-callout\; id="4"\; label="\lambda "\; filenames="DE102021127448A1\_0008.png,DE102021127448A1\_0009.png"\; state="\{\{state\}\}">\lambda </figure-callout>}}{4}-\text{Condition}$

in the case of oblique incidence, this results in the following form: $$\frac{\mathrm{<figure-callout\; id="2"\; label="\lambda "\; filenames="DE102021127448A1\_0008.png,DE102021127448A1\_0011.png"\; state="\{\{state\}\}">\lambda </figure-callout>}}{2}=n_1\left({\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="DE102021127448A1\_0011.png"\; state="\{\{state\}\}">w</figure-callout>}}_1+{\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="DE102021127448A1\_0011.png"\; state="\{\{state\}\}">w</figure-callout>}}_{1\mathrm{right}}\right)-n_0\cdot x$$

• - n₁ die Brechzahl des Material der Antireflexionsbeschichtung 10 und
• - n₀ die Brechzahl des Ursprungsmediums, hier Luft, die eine Brechzahl n₀ = 1,0003 hat.

The meaning of the formula letters 9 be removed. Anyway is

• - n ₁ the refractive index of the material of the anti-reflection coating 10 and
• - n ₀ the refractive index of the original medium, here air, which has a refractive index n ₀ = 1.0003.

In order to achieve a smoothing of the transmission curve, it is necessary for the antireflection coating 10 not to be constantly applied to the cover pane 4 with the same layer thickness d. Therefore, the antireflection coating 10 instead has b321 or b21 or b1 ( 5 until 7 ) different layer thicknesses d.

In order to optimize the layer thickness d of the anti-reflection coating of the respective sub-area b321 or b21 or b1 with regard to the different angles of incidence α, with which the beams of rays c1 to c3 are incident on the surface of the anti-reflection coating 10, the angles of incidence α are first determined according to the table 10 weighted. A weighting factor results for each angle of incidence α. The weighting factors are assigned to the angles of incidence α in a graduated manner. In other words, a first weighting factor is assigned to a range of the angle of incidence α, whereas a different weighting factor is assigned to another range of the angle of incidence α.

Alternatively, it is also possible to specify a function that uniquely assigns only a single angle of incidence α to each weighting factor. The Ver division of the weighting factors determines the course of the curve after the in 8th diagram shown.

In any case, an optimized transmission angle α ₀ of the laser beams can be determined, which results from the weighted arithmetic mean of the angles of incidence α, with which the quasi-collimated beams of rays c1, c2, c3 of the light components s1, s2, s3 hit the respective sub-area under consideration b321, b21, b1 strike.

11 shows the calculation of the optimized transmission angle α ₀ using a table for the three sub-areas b321, b21, b1. In this way, the optimized transmission angle α ₀ can be determined for the entirety of all affected light components s1, s2, s3 for the respective partial area b321 or b21 or b1.

The optimized transmission angle α ₀ is used in the following formula to calculate the layer thickness d for the respective sub-area b321 or b21 or b1, which is necessary to achieve the best possible degree of transmission for the entirety of the beams c1, c2, c3 . $$\mathrm{i.e}=\frac{\mathrm{<figure-callout\; id="4"\; label="\lambda "\; filenames="DE102021127448A1\_0008.png,DE102021127448A1\_0009.png"\; state="\{\{state\}\}">\lambda </figure-callout>}}{4}\cdot \frac{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DE102021127448A1\_0011.png"\; state="\{\{state\}\}">n</figure-callout>}}_1\text{cos}({\text{sin}}^{-1}\left(\text{sin}{\propto }_0\cdot \frac{n_0}{n_1}\right))}{si{n}^2\left(a_0\right)-{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DE102021127448A1\_0011.png"\; state="\{\{state\}\}">n</figure-callout>}}_1{}^2}$$

The following is based on 12 until 16 explains how the antireflection coating 10 is applied, which has the partial areas of different layer thickness d.

12 shows a perspective view of a movable template 12, which is designed as a sheet metal strip that is so thin and flexible that it can be wound on and off two rolls 14, 16. For this purpose, the rollers 14, 16 can be rotated about axes of rotation 17 in two directions of rotation, of which only one direction of rotation 28, clockwise, is shown in the drawing by means of an arrow. Each of the two ends of the sheet metal strip is connected to one of the rollers 14, 16 respectively.

The template has a plurality of geometrically defined recesses 18, 20, 22, 24, 26 which differ from one another in terms of shape and/or size. If the rollers 14, 16 are rotated together in one direction of rotation 28, the recesses 18, 20, 22, 24, 26 change their position in relation to the rollers 14, 16.

13 shows a device for the anti-reflection coating of the cover plate 4 in a view in the direction of the axes of rotation of the rollers 14, 16 12 . This device is arranged in a housing not shown in detail. A vacuum can preferably be created within this housing.

The template 12 is at a distance z1 from the cover plate 4, which, contrary to the illustration in 13 can vary over the length of the portion of the template 12 spanned between the rollers 14, 16 since the cover disk 4 of the LIDAR assembly is preferably curved.

The template 12 is arranged between the cover plate 4 and an emitting device 30 . The emitting device 30 comprises a heat source, not shown in detail, an evaporator shell 32 and an emitter 34 which is a solid and which is located in the evaporator shell 32 . The evaporator shell 32 has an opening 36 which faces the template 12 and the cover plate 4 .

In 14 a first coating step is shown in which the evaporator shell 32 and thus also the emitter 34 are heated by means of the heat source, so that the material of the emitter 34 changes from the solid to the gaseous state.

The gaseous material is conducted at least through the first cutout 18 of the stencil 12 and is deposited on the cover pane 4 as a first partial area 38 of the anti-reflection coating 10 . Additional gaseous material is retained at the edge portions of template 12 surrounding first recess 18 . As the coating time progresses, the first layer thickness d1 of the partial area 38 or its material thickness increases. The layer thickness d1 can thus be determined over the coating time in nm/s.

At the latest when the first partial area 38 has reached the desired first layer thickness d1, the rollers 14, 16 are rotated about their axes of rotation 17 and the first recess 18 and the second recess 24 thus change their position.

In the subsequent further coating step, the state results 15 , in which the second recess 24 is positioned between the cover plate 4 and the emitter 34 . The second recess 24 is larger than the first recess 18. The material is emitted by the emitter 34 and then passed through the second recess 24 in gaseous form. The material is then deposited in solid form on a previously uncoated surface area 42 of cover pane 4 . In addition, the material forms a second portion 40, the first part rich 38 overlapped. The two partial areas 38, 40 produced in the first coating step and the second coating step partially overlap in the middle. The coating time is longer for further coating steps than for the first coating step.

The further coating step can be repeated once more or several times, so that, for example, a third, a fourth, etc. coating step is carried out.

16 12 shows an example of the case in addition to the second coating step 15 a third coating step is also carried out. In this example, an antireflection coating is formed which has three partial areas of different layer thicknesses d1, d2, or d3. The largest layer thickness d3 is formed from the two underlying layer thicknesses d1 and d2, so that d3 = d1 + d2 applies. A defined distribution of the different layer thicknesses d1, d2, d3 takes place in different geometric areas of the cover plate 4.

The defined distribution of the layer thickness can thus take place sequentially by carrying out one coating step after the other. In this respect, a correspondingly shaped recess of the template 12 can be positioned between the emitter 34 and the cover plate 4 for each partial area.

However, the defined distribution of the layer thicknesses does not necessarily have to be sequential. Instead, it is also possible to apply the antireflection coating to the cover pane 4 precisely using an individual combination of coating time, movement speed of the movable template 12 and the geometry of the cutouts 18, 20, 22, 24, 26. The speed of movement of the movable template 12 can be a rotational speed of the rollers 14, 16 in particular. However, the movement speed can also be a linear movement of a template that is not rolled up. In any case, the stencil is also moved in this case while the cover plate 4 is being coated through a recess in the stencil.

By varying the distance z between the movable template and the cover plate 4, it is also possible to change the gradient of the layer thickness d. Out of 17 it can be seen that with a large distance z2, there is a very smooth transition from maximum layer thickness to a standard distance z3, which consists of 18 is evident.

Figure 19 shows the anti-reflection coating method for a small distance z3. The layer thickness decreases with a hard gradient at the edges of the partial areas. In this respect, clear steps are formed.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 053304481 [0002]

Claims (11)

LIDAR assembly (2) for a motor vehicle, which has at least two light components (s1, s2, s3) and a transparent cover plate (4) through which the light beams of the light component (s1, s2, s3) pass, the Light components (s1, s2, s3) have optical axes (5, 6, 8) that are skewed or at an angle to one another, with an anti-reflection coating (10) with different layer thicknesses (d1, d2, d3 ) is provided. LIDAR assembly after claim 1 , characterized in that the one anti-reflection coating (10), in particular in the area in which the light beams of the light components (s1, s2, s3) occur, is the only coating of the cover plate (4). LIDAR assembly according to one of the preceding claims, characterized in that the anti-reflection coating (10) comprises in particular hexamethyldisiloxane and that the cover plate (4) comprises in particular polycarbonate. LIDAR assembly according to one of the preceding claims, characterized in that the antireflection coating (10) is arranged on the side of the cover plate (4) facing the light component (s1, s2, s3). LIDAR assembly according to one of the preceding claims, characterized in that the light beams are laser beams, that the anti-reflection coating (10) is optimized in terms of a transmittance of the laser beams and that the layer thicknesses (d1, d2, d3) of the anti-reflection coating (10) depending on the angles of incidence (α) of the laser beams on the cover plate (4) are fixed. LIDAR assembly after claim 5 , characterized in that the layer thickness (d) of the anti-reflection coating is different on individual sub-areas (b1, b21, b321) of the anti-reflection coating (10) and that the layer thickness (d) on at least two sub-areas (b1, b21, b321) after the formula $$\mathrm{i.e}=\frac{\lambda }{4}\cdot \frac{n_1\text{cos}({\text{sin}}^{-1}\left(\text{sin}{\propto }_0\cdot \frac{n_0}{n_1}\right))}{si{n}^2\left(a_0\right)-n_1{}^2}$$

determined, - where α ₀ is an optimized transmission angle of the laser beams, which results as the weighted arithmetic mean of individual angles of incidence α, with which beams (c1, c2, c3) of quasi-collimated laser beams of the light components (s1, s2, s3) on impinge on the sub-area under consideration (b1 or b21 or b321), - where λ is the wavelength of the laser beams, - where n ₁ is the refractive index of the material of the anti-reflection coating (10) and - where n ₀ is the refractive index of air. Method for coating a cover plate (4) of a LIDAR assembly (2), in particular according to one of Claims 1 until 6 , characterized in that - the cover plate (4) and a movable stencil (12) are positioned relative to one another in such a way that the stencil (12) is arranged between the cover plate (4) and an emitter (34) for a material of the anti-reflection coating (10). - in a first coating step, the material is emitted by the emitter (34) and is then conducted in gaseous form through at least a first recess (18) in the stencil (12) and as a first partial area (38) of the anti-reflection coating (10) on the cover pane (4) is deposited, - a further recess (24), which differs in shape and/or size from the first recess (18) of the stencil (12), is positioned between the cover plate (4) and the emitter (34). , and - in a further coating step, the material is emitted by the emitter (34) and is then conducted in gaseous form through at least the further recess (24) and is deposited on the cover pane (4) as a further partial region (40) which is at least partially overlaps the first partial area (38) and/or covers a previously uncoated surface area (42) of the cover pane (4). procedure after claim 7 , characterized in that the first and the further recess (18, 24) are arranged on a common template (12) and that the template (12) is moved for a change between the coating steps. procedure after claim 8 , characterized in that the template (12) when changing the recess (18, 24) is partially wound onto a roll (14 or 16) and/or partially unwound from a roll (16 or 14). Procedure according to one of Claims 7 until 9 , characterized in that the emitter (34) is a solid which is heated to emit the gaseous material for the anti-reflective coating (10). Procedure according to one of Claims 7 until 10 , characterized in that a coating parameter between the first and the second coating step is changed, this coating parameter being the coating time and/or the distance (z1, z2, z3, z4) between the template (12) and the cover plate (4).

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