US-12619012-B2 - Optical device and injection molding method for producing same

US12619012B2US 12619012 B2US12619012 B2US 12619012B2US-12619012-B2

Abstract

An optical device includes: a transparent substrate and a coherent transparent layer enclosing the substrate in at least three places, which: forms a plurality of first optical lenses on a first surface and forms a plurality of second optical lenses on a second surface of the substrate arranged opposite the first surface, the transparent layer having a predetermined thickness. A method of manufacturing the optical device is also provided.

Inventors

Steffen Jentsch
Martin Mueller
Horst Wodak
Martin Rümmelein

Assignees

FEV Group GmbH
UPT-OPTIK WODAK GMBH

Dates

Publication Date: 20260505
Application Date: 20231108
Priority Date: 20210508

Claims (11)

1 . An optical device comprising: a transparent substrate; a coherent transparent layer enclosing the substrate in at least three places, which forms a plurality of first optical lenses on a first surface and forms a plurality of second optical lenses on a second surface arranged opposite the first surface of the substrate, the transparent layer having a predetermined thickness; and an image-bearing layer arranged between the substrate and at least one lens-forming portion of the transparent layer.
2 . The optical device according to claim 1 , wherein the transparent layer is produced by overmolding the substrate.
3 . The optical device according to claim 1 , wherein the transparent layer comprises an injection point on a substrate side facing away from the lenses.
4 . The optical device according to claim 1 , wherein the transparent layer has a thickness in a range of 0.5 mm to 5 mm.
5 . The optical device according to claim 1 , wherein the transparent layer has a thickness such that at least one second optical lens lies in a focal point of a first optical lens and at least a partial region of the image-bearing layer lies in the focal point of the at least one second optical lens.
6 . The optical device according to claim 1 , wherein the substrate consists of a substrate material and the transparent layer consists of at least one layer material which has a lower melting and/or glass transition temperature than the substrate material.
7 . The optical device according to claim 1 , wherein the first optical lenses and the second optical lenses have the same dimensions.
8 . The optical device according to claim 7 , wherein: the first optical lenses consist of a first layer material with a first refractive index and the second optical lenses consist of a second layer material with a second refractive index; the first refractive index is so large that at least one second optical lens lies in a focal point of a first optical lens; and the second refractive index is so great that at least a partial region of the image-bearing layer lies in the focal point of the at least one second optical lens.
9 . A method of manufacturing an optical device, comprising the steps of: S 1 : applying an image-bearing layer to a transparent substrate; S 2 : positioning the substrate in an injection mold; and S 3 : injection molding of a layer-forming material into the injection mold, so that the layer-forming material, by solidifying, forms a coherent transparent layer which encloses the substrate on at least three sides and which forms a plurality of first optical lenses on a first surface and which forms a plurality of second optical lenses on a second surface arranged on a side of the substrate opposite to the first surface.
10 . The method according to claim 9 , wherein during injection molding in step S 3 liquid layer-forming material flows around the substrate simultaneously on at least three sides.
11 . The method according to claim 9 , wherein the injection molding in step S 3 comprises the sub-steps: S 3 a : injection molding of a first portion of the transparent layer comprising the first optical lenses, S 3 b : repositioning the substrate and/or an injection molding tool, S 3 c : injection molding of a second partial region of the transparent layer, comprising the second optical lenses, wherein the second partial region is bonded to the first partial region in a material-locking manner.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/DE2022/100306, filed on Apr. 22, 2022, which claims priority to and the benefit of DE 102021002458.3 filed on May 8, 2021. The disclosures of the above applications are incorporated herein by reference. FIELD The present disclosure relates to an optical device and a method of manufacturing an optical device. BACKGROUND The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. DE102015121691 A1 discloses a method for producing a micro-lens array comprising at least one light-permeable base body with a flat extension, wherein the base body has a micro-lens structure on at least one base surface. At least one base body is produced with an injection molding tool in an injection molding process, so that the micro-lens structure is molded from a negative structure in the injection molding tool. SUMMARY This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features. The optical device according to the disclosure of the present application includes a transparent substrate, and a coherent transparent layer enclosing the substrate on at least three sides, which forms a plurality of first optical lenses on a first surface, and forms a plurality of second optical lenses on a second surface arranged opposite the first surface of the substrate. The transparent layer has a predetermined thickness. Substrates and/or layers that are permeable to a certain proportion of incident light of a certain wavelength are regarded as “transparent”. Preferably, the specific proportion of transmitted light in a wavelength range between 400 nm and 750 nm is greater than 90%. The invention is intended specifically for use as a microscope projector. It is based on the task of creating a low-cost optical element with a small installation space, which can project a sharp, undistorted image. Since the coherent transparent layer encloses the substrate on at least three sides and has a predetermined thickness, the optical device according to the disclosure of the present application can be produced by overmolding the substrate with a layer-forming material. During overmolding, flowable layer-forming material can be distributed over a layer-forming injection molding space around the substrate and enclose it. This results in a substrate-enveloping layer during solidification, which gives the optical device a high mechanical robustness and prevents individual lenses from detaching. Preferably, the optical device according to the disclosure of the present application includes an image-bearing layer which is arranged between the substrate and at least one lens-forming portion of the transparent layer. This makes it possible to use the optical device as a projector. Preferably, the transparent layer includes an injection point on a substrate side facing away from the lens. From the injection point, a flowable layer-forming material is distributed in the layer-forming injection molding space during a manufacturing process. The fact that the injection point is located on a substrate side facing away from the lens ensures that an optically functional area of the optical device is not impaired by injection defects and/or production-related artifacts, such as injection webs. Preferably, the transparent layer of the optical device according to disclosure of the present application has a thickness in the range of 0.5 mm to 5 mm. Particularly preferably, the thickness is between 0.5 mm and 1 mm. As a result, a sufficient material flow can be ensured in a manufacturing process with an injection molding process. Preferably, the transparent layer of the optical device according to the disclosure of the present application is so thick that at least one second optical lens lies in a focal point of a first optical lens and at least a partial area of the image-bearing layer lies in the focal point of the at least one second optical lens. This enables sharp projection of image information stored in the image-carrying layer. Particularly preferably, the substrate of the optical device according to the disclosure of the present application consists of a substrate material, such as glass, and the transparent layer consists of a layer material which has a lower melting and/or glass transition temperature than the substrate material, such as polycarbonate (PC), polymethyl methacrylate (PMMA), cycloolefin polymer (COP), cycloolefin copolymer (COC) or other optically transparent plastics, in particular polymers with thermoplastic behavior. This makes it possible to manufacture the optical device in a process temperature range in which the substrate material is temperature-stable and the coating material is injection-moldable. As a result, temperature-induced damage to the substrate, such as deformation or melting