Patent Application
20240159943
This application claims the right of priority of German Patent Application No. DE 10 2022 129 959.7, filed Nov. 11, 2022, the contents of which are incorporated by reference herein in their entirety.
The invention relates to a method according to claim 1 and an optical module according to claim 7.
Optical modules are used in various applications to direct or focus light beams. In imaging optical systems with a camera, such an optical module can be designed as a collecting optical system that generates an optical image of an object that can be captured by means of an image sensor. One possible application of such optical modules is related to mobile phones. It is desirable to be able to change the optical properties of such an optical module as required in order to be able to react to variable operating conditions.
In order to be able to guarantee the economic usability of optical modules in mobile phones, it must furthermore be ensured in the production of the optical modules that they are manufactured with low scrap rates. Therefore, achieving a high-yield optical module is critical to push the boundaries of mobile phone cameras. At the same time, it is desired to keep production costs low. Since image sensors have increased in size while pixels are becoming smaller the requirements for optical modules have developed to a point where it has become challenging to achieve the required specifications.
It is an objective of the invention to propose a method for the manufacture of an optical module as well as an optical module that allow the existing requirements to be met.
The objective is solved by a method according to claim 1 and an optical module according to claim 7. Preferred embodiments are subject-matters of dependent claims.
According to the invention, the method for manufacturing an optical module, comprises the following steps
In the following, examples of the present invention and its preferred embodiments are described with reference to the accompanying drawings.
It is an advantage of the invention, that a tunable optical component is used to set the optical properties of the optical module in a simple manner. Furthermore, it is an advantage that said tunable optical component, which is quality critical for the optical module, can be controlled with respect to its quality before it is assembled with further components of the optical module. Particularly, a higher production yield can be achieved. At the same time, the overall height of the optical assembly is reduced.
According to the invention, the tunable optical component has at least one optical property, which can be adjusted by altering the shape of the internal space. The invention is not limited to a specific design of the tunable optical component or which optical property is adjustable. Preferably, the first optical surface and the second optical surface are each at least partly transparent in an area that is arrangeable in an optical path of the tunable optical component. The invention is not limited to how the optical path of the optical module extends. Rather, it is within the scope of the invention that the optical path is linear or angular. At least in the context of the invention described here, in the case of a linear optical path, the term optical axis can be used synonymously.
Preferably, the first optical surface and the second optical surface are relatively displaceable to each other. A deformation of the internal space can therefore basically take place by completely or partially displacing the first optical surface and the second surface relative to each other. Preferably, the internal space in relation to the optical path of the optical tunable component is laterally limited by a circumferential element, such as a bellow, which may be flexible. By deforming the internal space, an optical property of the tunable optical component is adjusted such that the quality of a captured image may be improved effectively, if the optical module is part of an optical imaging system.
Preferably, in at least one state of the tunable optical component, the first optical surface and/or the second optical surface are flat and spaced parallel to each other. It is also within the scope of the invention that, in at least one state of the imaging optical system, the first and/or the second optical surface each have a curved shape. The invention is not limited to a specific transparent liquid, which, in a simple embodiment, may be an optical oil or another suitable liquid. By deforming the internal space, it is possible to influence a light beam entering the optical imaging system along the optical path.
It is also within the scope of the invention that the first optical element is at least partially transparent and arranged in an optical path that impinges both the first and the second optical surface. It is an advantage that a transparent window, in particular a flat glass window, can be used as the first optical element. The flat glass allows for a reduced requirement on the centering of the glass and therefore for a higher production yield.
The second optical element can be used to refocus and/or redirect a beam of light that passes through the tunable optical component and the first optical element along the optical path. The second optical element can be an optical folding element such as a prism or a mirror. Alternatively, the second optical element may also be a solid lens. Regardless of the embodiment of the second optical element, it is an advantage that no air gap is formed between the first and the second optical element. This makes it possible to achieve a compact design of the optical module.
It is essential to the invention that the optical property of the tunable optical component is measured before the first and second optical elements are joined in step D). This makes it possible to first ensure that quality-critical components of the optical module are of the required quality before they are assembled with other components to form the optical module. If it is determined during the measurement that the optical properties of the tunable optical component are not as desired, the tunable optical component can be excluded from the assembly process. This can prevent costly processing or manufacturing steps from being carried out on or with defective components.
According to a preferred embodiment of the invention, in step D) the second optical element is at least partially brought in direct contact with the first optical element. In particular, the joining of the second optical element with the first optical element comprises a formation of a van-der-Waals-bond and/or a chemical bond, in particular an adhesive chemical bond, and/or a plasma activated bond.
Investigations have shown that the aforementioned joining methods can be used to create a reliable connection between the first and second optical elements. At the same time, impairment of the optical properties of the first and second optical elements can be avoided, since the joining methods mentioned are particularly non-damaging or harmful with regard to the first and second optical elements.
According to a preferred embodiment, in step D) the second optical element and the first optical element are free of an antireflection coating, particularly in a contact zone.
It is an advantage of the above-described further development that additional process steps, in which the first and the second optical element are coated are avoided in the manufacture of the optical module. This saves material costs, in particular because no costly anti-reflective coatings need to be used, compared to arrangements with an air gap. In addition, the time required to assemble the optical module can be reduced.
According to another preferred embodiment, in step B) a quality information of the tunable optical component and/or the first optical element is determined as a function of the measured optical property. In particular, step B) comprises an optical measurement of the optical property of the tunable optical component and/or the first optical element.
An optical measurement of the tunable optical component and/or the first optical element allows a quality control that is both reliable and easy to automate. This further improves the production of the optical module.
As mentioned above, the invention also relates to an optical module according to claim 7.
According to the invention, the optical module comprises a tunable optical component at least with two optical surfaces and a deformable internal space between the two optical surfaces. The internal space is filled with a transparent liquid, and wherein an optical property of the tunable optical component is adjustable by altering a shape of the internal space. The optical module also comprises a first optical element that is attached to one of the optical surfaces facing away from the internal space. A second optical element is kitted to the first optical element via a van-der-Waals-bond and/or a chemical bond, in particular an adhesive chemical bond, and/or a plasma activated bond.
Preferably, the optical module is manufacturable by a method according to the invention or a preferred embodiment of the method. In this respect, with regard to the advantages that can be achieved with the optical module according to the invention, the explanations on the method according to the invention or an advantageous further development thereof apply accordingly.
According to a preferred embodiment, a contact zone between the first optical element and the second optical element is free of an antireflection coating. This reduces the manufacturing costs for the optical module.
According to another preferred embodiment, the tunable optical component is a tunable lens, wherein in particular the optical surfaces of the tunable optical component each are deformable membranes. Moreover, the first optical element is a transparent window that is attached to one of the deformable membranes.
By means of the above described embodiment, a deformation of at least one of the membranes may serve to deform the internal space and to change at least one optical property of the tunable optical component. An relative adjustment of the first optical element with respect to the tunable optical component serves to change the pressure of the liquid in the internal space and thereby cause a curvature of one of the membranes. It is within the scope of the preferred embodiment that the tunable optical component is moveable with respect to the first optical component.
According to another preferred embodiment, the tunable optical component is a tunable prism, wherein in particular the optical surfaces of the tunable optical component each are rigid optical windows. By adjusting the rigid optical windows relative to each other, an optical property of the tunable optical component can be set.
According to a preferred embodiment, the second optical element is a folding element, in particular a rigid prism or a mirror. The folding element can be considered as an optical component that deflects and/or diverges the path of a light beam. Preferably, the first folding element defines a first light entry axis and a first light exit axis that enclose a folding angle of at least 30°, preferably at least 45°, highly preferred 90°.
According to another preferred embodiment, the second optical component is a ridig lens. Such a rigid lens preferably has an optical axis, which in at least one state is substantially coaxial with the optical axis of the tunable optical component. The rigid lens may be part of a lens barrel comprising a plurality of rigid lenses.
In a preferred embodiment, the tunable optical component and the first optical element are moveably mounted with respect to each other. At least one actuator is designed to cause a relative displacement and/or a relative rotation between the tunable optical component and the first optical element in order to change at least one optical property of the tunable optical component.
In a simple embodiment, the actuator is electromechanical and comprises at least one electric coil and at least one magnet. In particular, the magnet can be mechanically coupled to the tunable optical component. Preferably, the magnet is arranged in such a way that when a current flow is generated in the coil, a force is exerted on the magnet and this force is transmitted to the tunable optical component. This can generate a relative displacement between the tunable optical component and the first optical element. In particular, the tunable optical component can be moved towards or from the first optical element in such a way that the internal space is deformed.
According to a preferred embodiment, the tunable optical component and the first optical element are displaceable along an optical axis of the optical module. The actuator is designed to cause a linear displacement between the tunable optical component and the first optical element, in particular to change a focal power of the tunable optical component.
An advantage of the advantageous further development described above is that it is possible to map a focusing function by means of the optical module by changing the focal power. This is particularly advantageous when the optical module is used as a part of an imaging optical system.
According to another preferred embodiment, the tunable optical component and the first optical element are displaceable about at least one tilt axis that runs perpendicular to the optical axis of the optical module. The actuator is designed to cause a rotation between the tunable optical component and the second optical element about the tilt axis, in particular to cause an optical image stabilization with the optical module.
An advantage of the further development described above is that the optical module can be used in mobile devices such as mobile phones. In order to improve the image quality, it is possible to compensate for the negative influence of an unsteady guidance of the mobile phone by performing an optical image stabilization.
For a better understanding, the reference numerals as used in
Regardless of the specific form of application, the optical module 1 comprises at least one optical property that be changed in a simple manner. In particular, the optical module 1 shown can be used to change its focal power as required and thus achieve an autofocus function. It is also possible to perform optical image stabilisation and thus compensate for undesired movements of the optical system in which the optical module 1 is used. This can significantly improve the image quality. The optical module 1 is also advantageous because its design allows the quality of optical systems, in which the optical module 1 is applied, to be improved.
The optical module 1 shown in
By adjusting the two optical surfaces 3 and 4 relative to each other or by deforming at least one of the optical surfaces 3 or 4, it is possible to change at least one optical property of the optical module 1 and thereby, as mentioned above, to change a focal power or to achieve optical image stabilisation.
On a side facing away from the internal space, the second optical surface 4 is connected to a first optical element 8. The first optical element is designed as a transparent window, which is also arranged along the optical path 6.
As will be explained in detail below, the first optical element 8 is mounted in a resting position relative to the tunable optical component 2. In other words, the tunable optical component 1 can be moved relative to the first optical element 8. By applying an adjusting force or torque to the tunable optical component 2, it is possible to move it towards or away from the first optical element 8 and thereby cause a deformation of the internal space.
It is essential to the optical module 1 shown in
The first optical element 8 and the second optical element 9 have a common contact zone 10. In the contact zone 10, the first optical element 8 and the second optical element 9 are connected to each other by means of an adhesive bond. In an alternative embodiment, the first optical element 8 and the second optical element 9 can also be at least partially connected to each other by means of a van der Waals connection or a plasma-activated connection.
An important advantage of the connection between the first optical element 8 and the second optical element 9 is that the tunable optical component 2 and the first optical element 8 can be assembled first and tested for their quality. Afterwards, the joining process takes place, in which the first optical element 8 and the second optical element 9 are joined together in the common contact zone 10.
By performing a quality control, which may include an optical measurement of the tunable optical component, prior to the joining step, a defective tunable optical component 2 can be excluded from the further assembly of the optical module. This means that value-adding production steps on defective components can be avoided, making production more efficient overall.
Furthermore, in the embodiment shown here, the contact zone 10 is free of an anti-reflection coating. This means that a corresponding coating process can be avoided, which saves both time and material costs.
In addition, the connection between the first optical element 8 and the second optical element 9 allows an air gap to be avoided, which reduces the overall height of the optical module 1.
For a relative adjustment of the tunable optical component 2 with respect to the first optical element 8, the optical module 1 comprises an actuator 11, which in this case has a plurality of magnets 12 and a plurality of coils 13. For a better overview, only one of the magnets and only one of the coils is marked with reference signs.
The magnets 12 are mechanically coupled to the tunable optical component 2 so that a movement of the magnets 12 can be transmitted to the tunable optical component 2.
The coils 13 are mounted at least in pairs with respect to the magnets 12 in such a way that, when an electric current is flowing, they can exert a magnetic field force on at least one of the magnets 12 in order to move it in a desired manner.
In particular, by moving the magnets 12, it is possible to cause the tunable optical component 2 to move parallel to the optical path 6 shown in
The settings of the tunable optical component 2 described above can be seen in
By adjusting the two optical surfaces 3 and 4 relative to each other or by deforming at least one of the optical surfaces 3 or 4, it is possible to change at least one optical property of the optical module 1 and thereby, to change a focal power or to achieve optical image stabilisation.
According to the optical module 1 shown in
By means of the optical module 1 shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2022 129 959.7 | Nov 2022 | DE | national |
