Device for mounting and adjusting an optical element

Abstract

The invention relates to a device for mounting an optical element (11) and adjusting same along the optical axis thereof, having a mount (12), in particular a cylindrical mount (12), for the optical element, wherein the mount (12) is mounted radially in a housing (15) by means of at least two diaphragm springs (13, 14) and the diaphragm springs (13, 14) are produced from a disc-shaped material having a modulus of elasticity which is greater than the modulus of elasticity of high-grade steel.

Description

[0001] Device for storing and adjusting an optical element

[0002] The mounting and adjustment of an optical element, particularly a lens or lens group, along its optical axis has already been achieved in various ways. Frequently, the optical element is held in a cylindrical mount, and the mount is guided longitudinally within a housing or other device component. By adjusting the mount, the distance of the optical element from an object to be recorded by a camera, for example, or from a workpiece to be processed by a laser beam, can be changed, and thus, in particular, the position of the optical element's focal point can be adjusted.

[0003] The socket can be radially mounted in the housing or device component using diaphragm springs, as the adjustment ranges are small and diaphragm springs allow deflection in both directions. Typically, stainless steel diaphragm springs with symmetrically arranged slots are used. However, it has been found that these stainless steel diaphragm springs have limited lateral stiffness. This leads to disadvantages regarding the size and the possible adjustment range of the diaphragm springs.

[0004] The invention is based on the objective of providing a device for the wear-free storage and adjustment of an optical element, which in particular has a higher transverse stiffness.

[0005] Description of the invention

[0006] This problem is solved according to the invention by a device for mounting an optical element and adjusting it along its optical axis with a socket, in particular a cylindrical socket, for the optical element, wherein the socket is radially mounted in a housing by at least two diaphragm springs and wherein the device is characterized in that the diaphragm springs are made of a disc-shaped material with a modulus of elasticity that is greater than the modulus of elasticity of stainless steel.

[0007] The higher modulus of elasticity allows the use of diaphragm springs with a smaller outer diameter than conventional stainless steel springs. The smaller surface area of ​​the diaphragm springs, resulting from a smaller outer diameter or a larger inner diameter, also allows for a larger free aperture. The device can therefore also be used for applications with high laser power. Furthermore, by using at least two diaphragm springs, a moment-free bearing arrangement can be achieved.

[0008] Preferably, the diaphragm springs can be made of a fiber-reinforced plastic, in particular a carbon fiber-reinforced plastic (CFRP). This allows the diaphragm springs to be manufactured thin yet very stable due to the embedded fibers, so that the required high elasticity can be achieved while still maintaining good transverse stiffness.

[0009] Further improvements in elasticity with good lateral stiffness can be achieved if the diaphragm springs are provided with several spiral slots.

[0010] If a diaphragm spring is arranged at both the upper and lower ends of the socket, the socket can be securely mounted against lateral displacement or tilting movements.

[0011] A drive device for adjusting the optical element along its optical axis can be attached to the mount in a manner known per se. It is advantageous if the drive device is positioned between two diaphragm springs on the mount. This minimizes the tilting moment during adjustment of the optical element. The mount is centered on both sides of the drive device by the diaphragm springs. The drive device is preferably a linear drive. This allows for very rapid shifts of the optical element's focal point within a small installation space.

[0012] If the drive device is also designed as a voice coil actuator, high repeatability and positioning accuracy can be achieved when adjusting the optical element. Furthermore, these actuators are wear-free and enable high accelerations.

[0013] Preferably, the inner diameter of the diaphragm springs can be greater than 10 mm, resulting in a larger free aperture of the device. This makes the device suitable for applications with high laser power.

[0014] The invention also relates to a laser processing system with at least one device according to the invention.

[0015] Preferably, the device can be used to adjust the focal point of a laser beam in the z-direction. This allows the focal point to be precisely positioned on a workpiece surface, for example, for laser cutting or laser welding. If the distance between the workpiece and the laser processing head of the system changes during processing, the position of the laser beam's focal point can be quickly adjusted. Typically, adjustment ranges of ± 8 mm for the optical element are sufficient for this purpose.

[0016] Advantageously, the device allows the adjustment of the laser beam's focal point in the z-direction to be performed at the same speed as a lateral adjustment of the laser beam using a galvanic scanner of the laser processing system. This enables the laser processing system to position the laser beam in three-dimensional space at high speed. Further features and advantages of the invention will become apparent from the description, the claims, and the drawing. According to the invention, the aforementioned and further described features can each be used individually or in any suitable combination. The embodiments shown and described are not to be understood as an exhaustive list, but rather serve as examples for illustrating the invention.

[0017] Detailed description of the invention and drawing

[0018] Fig. 1 shows a prior art device for storing and adjusting an optical element;

[0019] Fig. 2 shows a cross-section through a device according to the invention;

[0020] Fig. 3 shows a detailed view of a diaphragm spring of the device from Fig. 2.

[0021] Fig. 1 shows a prior art device 1 for adjusting a lens 2 in the z-direction. The lens 2 is held in a cylindrical housing 3. The housing 3, in turn, is mounted in a housing (not shown) by means of two diaphragm springs 4, 5. The diaphragm springs 4, 5 are made of stainless steel and each has a plurality of arcuate slots 4.1, 5.1. These slots 4.1, 5.1 increase the elasticity of the diaphragm springs 4, 5, but reduce their transverse stiffness. The adjustment of the lens 2 in the z-direction is effected by means of a drive unit acting at the end of the housing 3, of which a moving coil 6 is shown.

[0022] Fig. 2, in contrast, shows a device 10 according to the invention. In the device 10, an optical element 11 is also held in a cylindrical socket 12. This cylindrical socket 12 is supported wear-free by two diaphragm springs 13, 14 in a housing 15. In the illustrated example, the housing 15 is part of a laser processing head of a laser processing system (not shown). The diaphragm springs 13, 14 are made of a fiber-reinforced plastic and can therefore be manufactured with a smaller outer diameter and / or a larger inner diameter than the stainless steel diaphragm springs 4, 5 according to the prior art. The more precise appearance of the diaphragm springs 13, 14 will be explained in more detail with reference to Fig. 3. To adjust the optical element 11 in the z-direction and thus the focal point of a laser beam 16, a linear drive 17, which here is designed as a voice coil actuator, engages the socket 12.This type of drive enables very fast and wear-free movements of the socket 12. In contrast to the prior art, the linear drive 17 is arranged between the two diaphragm springs 13, 14 and not at one end of the socket 12, so that the socket 12 and thus the optical element 11 can be driven without tilting moment.

[0023] The device shown is suitable for movements of the optical element 11 of ±10 mm and high laser beam powers 16. The device 10 is therefore particularly suitable for high-power laser processing systems. A displacement measuring device (not shown) is provided on the housing 15 for measuring the adjustment path of the optical element 11.

[0024] The detailed view of the diaphragm spring 13 from Fig. 2 in Fig. 3 shows that the diaphragm springs 13, 14 are each provided with spiral slots 19, which contribute to increasing the elasticity of the diaphragm springs 13, 14 without impairing their lateral stability. The diaphragm springs 13, 14 are made of a fiber-reinforced plastic, preferably a CFRP material. However, other materials with a higher modulus of elasticity than stainless steel could also be used. Furthermore, the slots 19 do not necessarily have to be spiral in shape. Depending on the desired lateral stiffness, other configurations can be chosen.

Claims

Patent claims 1. Device for mounting an optical element (11) and adjusting it along its optical axis with a socket (12), in particular a cylindrical socket (12), for the optical element, wherein the socket (12) is radially mounted in a housing (15) by at least two diaphragm springs (13, 14), characterized in that the diaphragm springs (13, 14) are made of a disc-shaped material with a modulus of elasticity that is greater than the modulus of elasticity of stainless steel.

2. Device according to claim 1 , characterized in that the diaphragm springs (13, 14) are made of a fiber-reinforced plastic.

3. Device according to claim 1 or 2, characterized in that the diaphragm springs (13, 14) are provided with several spiral slots (19).

4. Device according to one of the preceding claims, characterized in that a diaphragm spring (13, 14) is arranged at the upper end and at the lower end of the socket (12).

5. Device according to one of the preceding claims, characterized in that a drive device (17) for adjusting the optical element (11) along its optical axis engages the socket (12).

6. Device according to claim 5, characterized in that the drive device (17) engages the socket (12) between two diaphragm springs (13, 14).

7. Device according to claim 5 or 6, characterized in that the drive device (17) is a linear drive device.

8. Device according to claim 7, characterized in that the drive device (17) is a voice coil actuator.

9. Device according to one of the preceding claims, characterized in that the inner diameter of the diaphragm springs (13, 14) is greater than 10 mm.

10. Laser processing system with a device (10) according to one of claims 1 to 9.

11. Laser processing system according to claim 10, characterized in that the device (10) is used to adjust the focus point of a laser beam (16) in the z-direction.

12. Laser processing system according to claim 11, characterized in that the device (10) makes it possible to adjust the focus point of the laser beam (16) in the z-direction at the same speed as a lateral adjustment of the laser beam (16) by means of a galvano-scanner of the laser processing system.

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