WO2005040865A1

WO2005040865A1 - Optical element for variable setting of the focal length on an optical device and optical device

Info

Publication number: WO2005040865A1
Application number: PCT/EP2004/011930
Authority: WO
Inventors: Dr. Andreas Obrebski
Original assignee: Carl Zeiss Surgical Gmbh
Priority date: 2003-10-23
Filing date: 2004-10-21
Publication date: 2005-05-06
Also published as: DE10349467A1

Abstract

An optical element (60) for variable setting of the focal length in an optical device is disclosed, with a housing container (62) which has a first medium (66) which is flexible in form and a second medium (67) which is flexible in form, whereby said media are non-miscible, the media are spatially located in the housing container (62), the second medium (67) at least partly rests on at least one support surface (68) within the housing container (62) and both media are in contact at at least one boundary surface (69). Means (70) for altering the size and/or the shape of the boundary surface (69) between the two media are also provided. According to the invention, the above may be achieved with a simple construction and in an energy-sparing manner, whereby the means (70) for altering the boundary surface(s) (69) is embodied to act on the first and/or second medium (66, 67), the means (70) for altering the boundary surface(s) (69) is embodied for the generation of a pressure on the first and/or second medium (66, 67) and that one medium may be displaced, in particular, pressurised by said means (70) at at least one boundary surface (69) in at least one preferred direction (61) towards the other medium.

Description

description

Optical element for variably adjusting the focal length in an optical device and optical device

The present invention initially relates to an optical element for variably adjusting the focal length in an optical device according to the preamble of claim 1 and according to the preamble of claim 8. Furthermore, the invention relates to an optical device.

Variable optical elements are already known from the prior art. Such a known solution is shown in FIG. 1. The known optical element 10 has a drop 13 of a conductive liquid which is applied to an insulation layer 12. The insulation layer 12 in turn covers a flat electrode 11. In the presence of an electrical field 14, which is caused by a voltage applied between the conductor liquid 13 and the electrode 11, the wetting can be significantly increased. As can be seen from FIG. 1, the drop 13 of conductor liquid in the idle state (FIG. 1a) has a considerably more compact and smaller contour than in the case of the application of a voltage (FIG. 1b). This well-known phenomenon is also known as electro-wetting.

An implementation of this phenomenon is known for example from US-A-5, 659,330. A display device is described therein, in which individual drops of a conductor liquid are arranged on an insulation layer. Electrodes are present below this insulation layer. By selectively creating an electric field, the shape of each drop of conductor fluid can be varied, thereby creating a colored pixel of an image. However, this known solution is unsuitable for optical elements in the form of adjustable lens elements. In particular, transparent electrodes would be required for such an application, so that the optical elements as a whole would be structurally complex and cost-intensive.

A solution of how the type of optical elements described above can also be used in the area of lens elements is described in DE 698 04 119 T2. The invention described therein, which is also shown by way of example in FIG. 2, lies in the field of adjustable focus lenses, and there in particular in the field of liquid lenses with an adjustable, electrically controlled focus. It should be possible to use the lens element described there to continuously adjust the focus with the aid of so-called “electrical wetting”. According to this known solution, an optical element 20 for changing the focal length is provided in conjunction with FIG. 2 generally the distance of the focal point to the plane of the optical element, for example to the lens plane.

The optical element 20 consists of a receptacle 22 which contains a first, electrically conductive liquid 28 and a drop of a second, insulating liquid 29. The two liquids 28, 29 are immiscible and spatially fixed in the receptacle 22. The two liquids 28, 29 touch one another at an interface 30. The drop of the second liquid 29 is arranged concentrically around the optical axis 21 of the optical element 20, the optical axis 21 likewise through a transparent region 24 of the bottom 23 of the receiving container 22 runs. The second liquid 29 bears at least in regions on electrodes 25 which are located within the receptacle 22. The electrodes 25 are in turn provided with an insulating layer 26. Finally, the known optical element 20 has means 31 for changing the interface 30 between the liquids 28, 29. An electrical field 27 can be generated between the conductive liquid 28 and the electrodes 25 via these means 31. This changes the wettability of the liquid 28, so that the shape of the drop of the second, insulating liquid 29 also changes. In the example shown in Figure 2 changes the shape of the drop of the liquid 29 in the presence of the electric field 27 from the flat shape shown in the form of a solid line to the curved shape shown in the form of a broken line, the broken lines each representing the interface 30 between the two liquids 28, 29 , The focus of the optical element can be continuously adjusted by varying the size and / or shape of the interface 30 between the two liquids 28, 29. Another known solution based on the principle of "electrical wetting" is described in WO 01/069380 A1.

Even if these known optical elements already represent an advantageous embodiment of a flexible lens element, the known solutions still have some disadvantages. For example, all systems operating on the principle of "electrical wetting" require relatively high voltages in the range from 100 to 170 V in order to achieve the desired effects.

In other solutions known from the prior art according to JP 60051801 A and JP 01302301A, optical elements are described in which an elastic film is arranged between two liquids. The two liquids are separated by this impenetrable film. The volumes of the liquids can be varied using pumps, which changes the curvature of the film. In the known solutions according to DE 19710668 A1, DE 298 23 857 U1 and JP 61056303 A, optical elements are described in which only one liquid is used at a time, which is located in a receptacle, which is covered on two sides by transparent films is limited.

Starting from the prior art mentioned, the present invention is therefore based on the object of developing an optical element of the type mentioned at the outset in such a way that the disadvantages described in relation to the prior art can be avoided. In particular, an optical element is to be provided with which a change in the focal length in an optical device can be implemented in a simple manner with at the same time low energy consumption. Furthermore, a correspondingly improved optical device is to be provided. This object is achieved according to the invention by the optical element with the features according to independent patent claims 1 and 8, the optical device with the features according to independent patent claim 24 and the advantageous uses according to independent patent claims 25 and 26. Further advantages, features, details, Aspects and effects of the invention result from the subclaims, the description and the drawings. Features and details that are described in connection with the optical elements according to the invention naturally also apply in connection with the optical device according to the invention and vice versa. The same applies to the uses according to the invention.

According to a first aspect of the invention, an optical element for variably adjusting the focal length is provided in an optical device, with a receptacle that contains a first flexible medium and a second flexible medium, the media being immiscible, the media in the receptacle are spatially fixed, the second medium abutting at least in regions on at least one contact surface within the receptacle and the two media touching at least one interface, and with means for changing the size and / or shape of the interface (s) between the two media , According to the invention, it is provided that the means for changing the interface (s) are designed to act on the first and / or second medium, and that the means for changing the interface (s) are designed to generate pressure on the first and / or second medium are formed and that a medium is displaced, in particular pressed, at least at one interface in at least one preferred direction in the direction of the respective other medium.

The present invention is based on the teaching according to DE 698 04 119 T2, the disclosure content of which is included in the description of the present invention. In this known solution, which works on the principle of "electrical wetting", the means for changing the interface between the two media act on the electrically conductive medium An electrical voltage changes the wettability of this electrically conductive medium, so that the contour of the electrically insulating medium can also change indirectly as a result.

In the solution according to the invention, on the other hand, the means for changing the interface act on the first and / or second medium in such a way that the corresponding medium is displaced by these means at the interface between the two media in at least one preferred direction in the direction of the first medium , in particular is or can be pressed. As will be described in more detail below, this preferred direction can be, for example, the optical axis of an optical element designed as a lens element.

In comparison to the solution known from the prior art according to DE 698 04 119 T2, it is no longer necessary to change the size and / or the interface between the two media by applying a high voltage. For this reason, none of the media used has to be electrically conductive, which considerably improves the choice of suitable media.

According to the invention, the means for changing the interface between the two media are now designed in such a way that they exert pressure on the first and / or second medium, the interface between the two media changing due to the application of the pressure. Such means, of which some non-exclusive examples will be explained in the further course, can be designed in a structurally simple and energy-saving manner, such means often only requiring very small control voltages.

If the optical element according to the invention is used to variably adjust the focal length in an optical device, the focal length can be changed without the individual components of the optical device having to be moved. In principle, the invention is not restricted to certain types of optical elements. For example, it is conceivable that the optical elements are variable lens elements or other, for example electrically controllable, optical elements. For example, it can be provided that the optical element according to the invention is designed as a lens element, for example as a spherical lens element, cylindrical lens element and the like, or as a prism element, for example as a prism element with variable spectral splitting power, or as a mirror element, for example as a switchable mirror, or the like. However, the optical element is particularly preferably used as a lens element with a variable focal length. Even if the invention is primarily described below on the basis of such an embodiment, it goes without saying that the invention is not restricted to this specific example.

According to the invention, the optical element initially has a receiving container which contains two different media. At least regions of individual outer walls of the container can preferably be formed from a transparent material.

There are two flexible media within the receptacle, the individual media being immiscible. Basically, the invention is not limited to certain media types. It is only important that the media are flexible in form. "Flexible in shape" in the light of the present description means that the media have no rigid surface, but that the media within the receptacle can change in shape. For example, but not exclusively, the first medium can be water and the second medium is an oil.

The media are preferably at least partially transparent and can, for example, have the same or at least a similar density in order to exclude gravitational effects. The two media are spatially fixed in the receptacle, the second medium bearing at least in regions on at least one contact surface within the receptacle. Likewise, of course, the first medium also bears, at least in regions, on at least one contact surface within the receptacle.

The contact surface can be located at different locations within the receptacle, so that the invention is not restricted to certain arrangement or design variants. Some non-exclusive examples are described below. The contact surface can be, for example, at least a partial area of an outer container wall, for example the container base and / or a cover element and / or at least one side wall. In the case of the latter variant, in particular an embodiment can be implemented in which the medium does not touch the bottom of the container, but only rests on the side walls. Of course, configuration variants are also conceivable in which the abovementioned contact surface is at least a partial area of an intermediate layer located in the interior of the receptacle. Where the medium abuts the contact surface of the receptacle, it is preferably formed from a transparent material, so that light entering the receptacle from the outside can radiate through the container walls and the transparent media located in the receptacle. In an embodiment in which the contact surfaces are formed by at least partial areas of the side walls, this is not absolutely necessary, possibly even harmful (scattered light), so that the contact surfaces can also be formed from a non-transparent material in such a case.

According to the invention, it is further provided that the two media touch at an interface. In order to change the focal length of the optical element, special means for changing the size and / or shape of the interface between these two media are provided. This means that pressure is exerted on the corresponding medium so that it can be shifted - in particular pressed - at the interface in at least one preferred direction in the direction of the other medium. In the case in which the optical element is designed as a lens element, this preferred direction can preferably be the optical axis of the lens element. The change in the focal length of the optical element and thus the change in the focal length in an optical device then takes place, as it were, by pressing out one medium in the direction of the other medium.

It can be provided, for example, that the means for changing the interface (s) are designed to act on the second medium and that the second medium is displaced, in particular pressed, at least at one interface in at least one preferred direction in the direction of the first medium. will or can become. Additionally or alternatively, it is also conceivable that the means for changing the interface (s) are designed to act on the first medium and that the first medium is displaced, in particular pressed, at least at one interface in at least one preferred direction in the direction of the second medium , will or can become.

In a further refinement, it can also be provided that the two media touch at two interfaces and that a medium is shifted, in particular pressed, or pushed in at least one preferred direction in the direction of the other medium via the means for changing the interfaces at one or both interfaces can be. In such a case, it is also possible, for example, that two preferred directions - one for each interface - can be selected. According to an advantageous development, the preferred directions can be oriented in opposite directions.

It can advantageously be provided that a medium is shifted, in particular pressed, in the direction of the other medium via the means for changing the interface (s) in such a way that the curvature of at least one interface between the two media changes. According to a second aspect of the invention, an optical element for variably adjusting the focal length is provided in an optical device, with a receptacle that contains a first flexible medium and a second flexible medium, the media being immiscible, the media in the receptacle are spatially fixed and with the two media touching at an interface, and with means for changing the size and / or shape of the interface between the two media. According to the invention, this optical element is characterized in that the second medium is enclosed on all sides by the first medium, that the means for changing the interface are designed to act on the first and / or second medium, and that the means for changing the interface are designed to generate a Pressure on the first and / or second medium are formed.

A special contact surface is not required with this solution. Rather, the second medium, which advantageously has a spherical configuration in the initial state, is surrounded on all sides by the first medium. The first medium can in turn be water, for example, and the second medium can advantageously be a suitable oil. The two media advantageously have the same density so that the second medium is held in position within the first medium and cannot sink, that is to say that gravitational effects can be effectively excluded.

The means for changing the interface now exert pressure on the first and / or second medium. When pressure is applied to the first medium, the pressure is transferred from the first to the second medium so that it is compressed at the pressure application point, which changes the size and / or shape of the interface between the two media. For example, the second medium can be brought into an elliptical configuration from the originally spherical initial shape. When pressure is applied to the second medium, it will expand against the first medium so that the size and / or shape of the interface between the two media will also change in this case. It can advantageously be provided that the means for changing the interface act on the first and / or second medium such that the curvature of the interface between the first and second medium changes.

As already explained above, the invention is not restricted to certain types of medium. For example, it can be provided that the first medium and / or the second medium is a liquid. For example, the first medium can be water, while the second medium is an oil. Of course, other types of media are also possible. Likewise, as described in DE 698 04 119 T2, the first medium can be an electrically conductive medium, while the second medium is electrically insulating. However, the electrical conductivity of at least one of the media is no longer required in the solution according to the invention.

Of course, the media can also be designed in a different way. It is only important that the media are flexible in form. It is therefore also conceivable, for example, that the first medium and / or the second medium is / are in the form of a gel.

It can advantageously be provided that the second medium is in the form of a drop. A drop is generally understood to mean a small amount of medium of spherical or elongated round shape, at least in some areas.

As already stated above, the first and second medium preferably have the same density.

In a further embodiment it can be provided that the first medium and the second medium have different optical properties, for example different optical indices. It can be provided, for example, that the first medium and the second medium have different refractive indices. According to an advantageous - not exclusive - example it is provided that the first medium has a low Refractive index (refractive index), while the second medium has a high refractive index.

If the media abut a transparent contact surface, for example on an at least partially transparent wall of the receptacle, these transparent areas of the contact surface or the container wall preferably have the same or a similar refractive index as the adjacent medium. This avoids broken beam paths and unwanted reflections.

It is advantageously provided that the first and / or second medium is spatially fixed within the receptacle. This is particularly important if the optical element is designed in the form of a lens element in which a beam path is to pass through the lens element in a defined manner. The spatial fixation is preferably carried out by means of suitable fixation means. However, the invention is not restricted to certain types of fixing agents. For example, but not exclusively, the fixing means can be designed in the form of a special surface design of the contact surface and / or in the form of a special surface quality of the contact surface. The surface is advantageously designed so that it can hold the medium in position. The special surface condition can be realized, for example, by means of a special surface coating. A special surface quality with regard to wettability can advantageously be provided. The invention is of course not limited to the examples mentioned.

For example, it is conceivable that the media are fixed by a suitable choice of surface materials and / or local surface coatings within the receptacle, for example the wall of the receptacle. Likewise, the spatial fixation of the media can be done by applying a suitable, preferably fixed voltage. In this case, it is advantageous if the first medium is designed as an electrically conductive medium and the second medium as an electrically insulating medium. Such a possibility is generally described in DE 698 04 119 T2, the disclosure content of which insofar as is included in the description of the present invention. Of course, it is also conceivable to achieve the spatial fixation via the structural design of the walls within the receptacle, for example by providing them with suitable projections, edges, undercuts, cutouts and the like.

The general purpose of the fixing means is that the position of the media within the receptacle remains unchanged, so that in particular a defined beam path can be generated via the optical element.

It can advantageously be provided that an opening is provided in the contact surface of the receptacle, for example in an intermediate layer - against which the second medium lies, and that the second medium is fixed in the region of this opening. The opening can in particular extend around an optical axis of the optical element, so that a light beam can pass through this opening and then through the first and second medium. In particular, all the components of the optical element in question are designed to be transparent in the area of the opening.

As has already been explained above, the invention is not restricted to certain configurations for the means for changing the interface. Some non-exclusive examples are described in more detail below.

For example, it is conceivable that the means for changing the interface are designed as mechanical means. In such a case, the mechanical means can be designed, for example, as a piston device or cylinder device.

In a further embodiment, it is also conceivable that the means for changing the interface are in the form of a controllable membrane. The invention is of course also not limited to certain types of drives for the means for changing the interface. For example, it is possible for the means to be designed to be electrically operable. The voltages required in such a case are in the lower volt range. Such agents are therefore particularly energy-saving and cost-effective. Of course, other types of drive for the means for changing the interface are also possible. For example, it is conceivable that they are magnetically and / or electromagnetically and / or pneumatically and / or hydraulically and / or piezoelectrically actuated. The selection of the appropriate type of drive depends on the type of application and location of the optical element.

With the optical element according to the invention, it is possible in a particularly simple and inexpensive way to implement a change in the focal length of the optical element. This can be done in a particularly simple manner by the selection of suitable parameters, for example the selection of suitable media - for example liquids - within the receptacle, the suitable design of the surfaces within the receptacle, the shape and size of the opening (s), the selection of the suitable one Angle of the interface curvature and the like.

Even if the optical element has only been described so far using two different media, it is of course also possible to use optical elements with three or more media within the receptacle, which is then designed differently in each case. The design and mode of operation of such optical elements are derived in an analogous manner from what has been described above, so that reference is made to the above statements in this regard.

According to the third aspect of the invention, there is provided an optical device with variable focal length, which has a number of optical elements. It is provided according to the invention that at least one of the optical elements is designed in a manner according to the invention as described above. The invention is of course not limited to specific types optical devices limited. The optical elements according to the invention can thus be used in all optical devices in which a change in the focal length is necessary. These can be, for example, video camcorders, cameras, binoculars, glasses with close and distant vision, adjustable glasses and the like. Such an optical device can particularly advantageously be a microscope, in particular an operating microscope, or an endoscope.

According to a further aspect of the invention, an optical element as described above is therefore used in a particularly advantageous manner in an optical device with variable focal length and / or with variable spectral splitting and / or with variable beam guidance, in particular in a microscope or an endoscope, or a telescope , or a telescope, or a camera, or a camcorder, or a camera in a mobile phone, or a magnifying glass, or a head magnifier.

The invention will now be explained in more detail using exemplary embodiments with reference to the accompanying drawings. Show it:

1 shows an optical element according to a first solution known from the prior art; FIG. 2 shows an optical element of a further solution known from the prior art; Figure 3 shows a first embodiment of an optical element according to the present invention; Figure 4 shows a second embodiment of an optical element according to the present invention; Figure 5 shows a third embodiment of an optical element according to the invention; and FIG. 6 shows yet another exemplary embodiment of an optical element according to the invention. The optical elements 10, 20 shown in FIGS. 1 and 2 have already been explained in connection with the introduction to the description, so that reference is made to the corresponding statements in this regard.

FIGS. 3 to 6 show optical elements according to the present invention, which are to be lens elements with a variable focal length. The optical elements are to be used in an optical device with variable focal length, for example in an operating microscope or an endoscope (not shown in each case).

The optical element 60 shown in FIG. 3 initially consists of a receptacle 62, which is delimited, among other things, by a container bottom 64 and a container lid 63 opposite this. The optical axis 61 runs perpendicular to the container bottom 64, along which the beam path 65 of a light beam runs through the optical element 60.

At least in an area around the optical axis 61, the container bottom 64 and also the container lid 63 have a transparent area. Of course, it is also conceivable that the entire container bottom 64 and the entire container lid 63 are formed from a transparent material.

Inside the receptacle 62 there are two different media 66, 67, each of which is flexible in shape. Both media 66, 67 cannot be mixed with one another, have different optical properties (different refractive indices n1 and n2) and at least have a similar density. In addition, both media 66, 67 are transparent. In the present exemplary embodiment, the form-flexible media 66, 67 can be liquids, for example the first medium 66 being water and the second medium 67 being oil.

Within the receptacle 62 there is an intermediate layer formed as a contact surface 68, which in turn has an opening 74. Just like the transparent area of the container bottom 64, the opening 74 is also formed concentrically around the optical axis 61 within the intermediate layer 68.

In the example shown in FIG. 3, those surfaces within the receptacle 62 that are wetted with the first medium 66 are identified by a dashed line, while those surfaces that are wetted with the second medium 67 are identified by a dash-dotted line.

The two liquids 66, 67 are spatially fixed in the receptacle 62 by suitable means, the second liquid 67 abutting at least in regions on the intermediate layer 68 formed as a contact surface within the receptacle 62. The second liquid 67 is also fixed in the area of the opening 74, so that the liquid 67, which has a teardrop shape at least in the area of the interface 69 between the first and second liquids 66, 67, extends concentrically around the optical axis 61.

A light beam 65 entering the optical element 60 thus first passes through the transparent area of the container bottom 64, then the second liquid 67 and the opening 74 in the contact surface 68 within the receiving container 62, then the first liquid 66 and then a transparent area of the container lid 63 ,

A change in the focal length of the optical element 60 and thus a change in the focal length of the optical device now takes place in such a way that the size and / or shape of the interface 69 - for example its curvature - between the two liquids 66, 67 is changed. This takes place via appropriately designed means 70. In the present exemplary embodiment, the means 70 for changing the interface 69 are designed in the form of a membrane 71 which forms part of the intermediate layer 68. At least one magnet or metal plate 72 is located on or in the membrane 71. An electromagnet 73 can be used to act on this plate 72. If the plate 72 is designed as a magnetic plate, depending on the polarity, this can be attracted when the electromagnet 73 is actuated in the direction of the container bottom 64, or can be pushed off in the direction of the container lid 63. If the plate 72 is designed as a metal plate, this is either attracted or pushed off when the electromagnet 73 is actuated.

The means 70 for changing the interface 69 now make it possible to act directly on the liquid 67. This is done in such a way that the second liquid 67 at the interface 69 to the first liquid 66 is pressed in at least one preferred direction - in the present example in the direction of the optical axis 61 - in the direction of the first liquid 66. This is done in a particularly simple and energy-saving manner by actuating the membrane 71.

In the initial state, the membrane 71 is in its horizontal starting position. The second liquid 67 has a teardrop shape on the contact surface 68, the interface 69 between the liquids 67 and 66 having a flat curvature. This is shown by a solid line.

If the electromagnet 73 is now actuated and the plate 72 is attracted, for example, in the direction of the container bottom 64, this leads to the membrane 71 also deflecting in the direction of the container bottom 64. As a result, the second liquid 67 is pressed out through the opening 74, as a result of which the curvature of the interface 69 changes into a substantially more curved shape, which is represented by a broken line. The second liquid 67 is thus pressed in the direction of the optical axis 61 in the direction of the first liquid 66, which likewise results in a change in the focal length of the optical device (not shown).

FIG. 4 shows another embodiment of an optical element according to the present invention, which has a further embodiment for the means for changing the interface. The optical element 40 shown in FIG. 4 initially consists of a receptacle 42, which is delimited, among other things, by a container bottom 43 and a container lid opposite it. The optical axis 41 runs perpendicular to the container bottom 43, along which the beam path 45 of a light beam runs through the optical element 40. At least in an area around the optical axis 41, the container bottom 43 and also the container lid have a transparent area 44. Of course, it is also conceivable that the entire container bottom 43 and the entire container lid are formed from a transparent material.

There are two different flexible media 46, 47 within the receptacle 42. Both media 46, 47 are not miscible with one another, have different optical properties and at least have a similar density. In addition, both media 46, 47 are at least partially transparent. In the present exemplary embodiment, the form-flexible media can likewise be liquids, the first medium 46, for example, being water and the second medium 47 being oil.

The first medium 46 lies against the container lid, which is transparent at least in some areas. The medium and the transparent area of the container lid advantageously have the same refractive indices n1, so that neither broken rays nor undesired reflections can occur. Likewise, therefore, the transparent area 44 of the container bottom 43 and the medium 47, which bears against the transparent area 44, have identical or similar refractive indices n2. The container lid and first medium 46, or container bottom 43 and second medium 47 can then be viewed as a single medium.

Within the receptacle 42 there is a contact surface 48 in the form of an intermediate layer, which in turn has an opening 52. Like the transparent area 44 of the container bottom 43, the opening 52 within the contact surface 48 is concentric around the optical axis 41 educated. Depending on the design, the intermediate layer can have a horizontal or an oblique orientation.

The two liquids 46, 47 are spatially fixed in the receiving container 42 by suitable means, the second liquid 47 resting at least in regions on the contact surface 48 of the receiving container 42. The second liquid 47 is also fixed in the area of the opening 52, so that the liquid 47, which has a teardrop shape at least in the area of the interface 49 between the first and second liquids 46, 47, extends concentrically around the optical axis 41. This can be achieved, for example, by suitable shaping and / or surface coating of the contact surface 48.

A light beam 45 entering the optical element 40 thus first passes through the transparent area 44 of the container bottom 43, then the second liquid 47 and the opening 52 in the wall 48 of the receiving container 42, then the first liquid 46 and then a transparent area of the container lid.

A change in the focal length of the optical element 40 and thus a change in the focal length of the optical device is now carried out in such a way that the size and / or shape of the interface 49 - for example its curvature - between the two liquids 46, 47 is changed. This is done using appropriately designed means 50. In the present exemplary embodiment, the means 50 for changing the interface 49 are designed in the form of a piston device 51, the piston 51 moving within a cylinder 53.

The means 50 for changing the interface 49 now make it possible to act directly on the liquid 47. This is done in such a way that the second liquid 47 at the interface 49 with the first liquid 46 is pressed in at least one preferred direction - in the present example in the direction of the optical axis 41 - in the direction of the first liquid. This is done in a particularly simple and energy-saving manner by actuating the piston device 51. In the initial state, the piston device 51 is in the initial position shown by a solid line. The second liquid 47 has a teardrop shape on the wall 48, the interface 49 between the liquids 47 and 46 having a flat curvature. This is also shown by a solid line.

If the piston device 51 is now actuated and displaced into a second position represented by the dashed line, for which only a small control voltage is required, the second liquid 47 is pressed out through the opening 52, as a result of which the curvature of the interface 49 becomes a much more curved shape changes, which is represented by a dashed line. The second liquid 47 is thus pressed in the direction of the optical axis 41 in the direction of the first liquid 46, which likewise results in a change in the focal length of the optical device (not shown).

The optical element 80 shown in FIG. 5 in turn has a receptacle 82 which is delimited by a cover element 83, a container bottom 84 and side walls 86, 87. At least in the region of the optical axis 81, along which the light beam direction 85 runs, the container bottom 82 and the container lid 83 are transparent.

In the receptacle 82 there are two flexible media 90, 91 with the same density but different optical properties. In the present example, the first flexible medium 90 has a refractive index n1, while the flexible second medium 91 has a refractive index n2. In contrast to the exemplary embodiments described above, the second medium 91 does not lie against the container bottom 84 or an intermediate layer located in the receiving container 82.

Rather, the contact surfaces 88, 89 in the present example are designed as partial areas of the side walls 86, 87. The second medium 91 is thus held on the side and not on the optical axis 81. The contact surfaces 88, 89 therefore do not have to be transparent. The surface is advantageous of the contact surfaces 88, 89 each designed such that the second medium 91 is held there.

The first medium 90 is located both above and below the second medium 91, so that the two media 90, 91 touch at two interfaces 92, 93.

In the example shown in FIG. 5, those surfaces within the receptacle 82 that are wetted with the first medium 90 are identified by a dashed line, while those surfaces that are wetted with the second medium 91 are identified by a dash-dotted line.

If means for changing the interfaces are not shown, the second medium 91 is pressed outwards, whereby the curvature of the interfaces 92, 93 change into a much more curved shape. The second medium 91 is thus pressed in two oppositely oriented preferred directions in the direction of the optical axis 81 in the direction of the first medium 90, which likewise results in a change in the focal length of the optical device (not shown).

Finally, FIG. 6 shows yet another exemplary embodiment of an optical element 100 according to the present invention, the sub-figures a) and b) each representing different operating states.

The optical element 100 in turn has a receptacle 102, among other things with a container bottom 103 and a lid element 104. In the present example, not only their areas around the optical axis 101 are to be made transparent. Rather, both the container bottom 103 and the cover element 104 should be transparent in their entirety. In addition, the container bottom 103 has a curved surface directed into the receiving container. Both the container bottom 103 and the cover element 104 have a refractive index n1 which is identical or similar to the refractive index n1 of a first medium 105 of flexible shape located in the receiving container 102. The first medium 105 can be water, for example, while the container bottom 103 and the lid element 104 are made of glass, for example.

In the receptacle 102 there is also a second flexible medium 106 with the same density as the first medium 105, but with a different refractive index n2. The second medium is, for example, an oil. The second medium 106, which is approximately spherical in the starting position according to FIG. 6a), is surrounded on all sides by the first medium 105. In contrast to the exemplary embodiments described above, the second medium is therefore not in contact with any contact surface. Since both media 105, 106 have the same density and the design of the container bottom 103 ensures that the second medium 106 is held in position in FIG. 6a.

A change in the focal length of the optical element 100 and thus a change in the focal length of the optical device now takes place in such a way that the size and / or shape of the interface 107 - for example its curvature - is changed between the two media 105, 106. This takes place via appropriately designed means 108. In the present exemplary embodiment, the means 108 for changing the interface 107 are designed in the form of a piston device 109, the piston 109 moving along its direction of displacement 110 within the receiving container 102.

For this reason, the piston device 109 is made of a transparent material, for example of glass. Furthermore, the piston device 109 advantageously has a refractive index n1 which corresponds to, or is similar to, the refractive index n1 of the first medium 105.

The means 108 for changing the interface 107 now make it possible to act directly on the first medium 105 and indirectly on the second medium 106. In the initial state, the piston device 109 is in the initial position shown in FIG. 6a. The second medium 106 has a spherical shape.

If the piston device 109 is now actuated and is displaced along the displacement direction 110 into a second position shown in FIG. 6b, the second medium is pressed into an elliptical shape, which also results in a change in the focal length of the optical device (not shown).

LIST OF REFERENCE NUMBERS

10 optical element

11 electrode

12 insulation layer

13 drops of conductive liquid

14 electric field

20 optical element

21 optical axis

22 receptacles

23 container bottom

24 transparent area of the container bottom

25 electrode

26 insulating layer

27 electric field

28 first liquid (electrically conductive)

29 second liquid (electrically insulating)

30 interface between the liquids

31 Means for changing the interface

40 optical element

41 optical axis

42 receptacles

43 tank bottom

44 transparent area of the container bottom

45 direction of light beam

46 first flexible medium

47 second flexible medium

48 contact surface (intermediate surface)

49 Media interface

50 means for changing the interface piston device

opening

cylinder

optical element optical axis

receptacle

container lid

container bottom

Direction of light beam first shape-flexible medium second shape-flexible medium

Contact surface (intermediate layer)

Interface between the media

Means for changing the interface

membrane

Tile

electromagnet

opening

optical element optical axis

receptacle

container lid

container bottom

Beam direction

Container sidewall

contact surface

Contact surface of first flexible medium, second flexible medium

Interface between the media 93 Interface between the media

100 optical element

101 optical axis

102 receptacles

103 tank bottom

104 container lid

105 first flexible medium

106 second flexible medium

107 Interface between the media

108 Means for changing the interface

109 piston device

110 Direction of displacement of the piston device

Claims

claims

1. Optical element for variably adjusting the focal length in an optical device, with a receptacle (22, 42, 62, 82), which has a first flexible medium (28, 46, 66, 90) and a second flexible medium (29, 47 , 67, 91), the media being immiscible, the media being spatially fixed in the receptacle (22, 42, 62, 82), the second medium (29, 47, 67, 91) being at least in regions at least a contact surface (23, 48, 68, 88, 89) rests within the receptacle (22, 42, 62, 82) and the two media touch at least one interface (30, 49, 69, 92, 93), and with means (31, 50, 70) for changing the size and / or shape of the interface (s) (30, 49, 69, 92, 93) between the two media, characterized in that the means (50, 70) for Changing the interface (s) (49, 69, 92, 93) to act on the first and / or second medium are designed so that the means (50, 70) for changing n of the interface (s) (49, 69, 92, 93) are designed to generate a pressure on the first and / or second medium and that a medium via these means (50, 70) at at least one interface (49, 69, 92, 93) in at least one preferred direction (41, 61, 81) in the direction of the other medium, in particular pressed, pushed or can be.

2. Optical element according to claim 1, characterized in that the means (50, 70) for changing the interface (s) (49, 69, 92, 93) are designed to act on the second medium (47, 67, 91) and that the second medium (47, 67, 91) via these means (50, 70) at at least one interface (49, 69, 92, 93) in at least one preferred direction (41, 61, 81) in the direction of the first medium ( 46, 66, 90) moved, in particular pressed, is or can be.

3. Optical element according to claim 1 or 2, characterized in that the means (50, 70) for changing the interface (s) (49, 69, 92, 93) for acting on the first medium (46, 66, 99) are trained and that that first medium (46, 66, 90) via these means (50, 70) at at least one interface (49, 69, 92, 93) in at least one preferred direction (41, 61, 81) in the direction of the second medium (47, 67 , 91) moved, in particular pressed, is or can be.

4. Optical element according to one of claims 1 to 3, characterized in that the two media touch at two interfaces (92, 93) and that a medium via the means for changing the interfaces (92, 93) at one or both interfaces (92, 93) in at least one preferred direction (81) in the direction of the other medium, in particular pressed, pushed or can be.

5. Optical element according to one of claims 1 to 4, characterized in that the contact surface (88, 89) within the receiving container (42, 62, 82) as at least a partial area of a cover element (63, 83) and / or a base element ( 44, 64, 84) and / or at least one side wall (86, 87).

6. Optical element according to one of claims 1 to 5, characterized in that the contact surface (48, 68) within the receptacle (42, 62) is formed as at least a partial area of an intermediate surface arranged within the receptacle (42, 62).

7. Optical element according to one of claims 1 to 6, characterized in that a medium is displaced via the means (50, 70) for changing the interface (s) (49, 69, 92, 93) in the direction of the other medium the curvature of at least one interface (49, 69, 92, 93) between the two media changes.

8. Optical element for variably adjusting the focal length in an optical device, with a receptacle (102) which contains a first flexible medium (105) and a second flexible medium (106), the media being immiscible, the media being in the Receiving containers (102) are spatially fixed and the two media touch at an interface (107), and with means (108) for changing the size and / or shape of the interface (107) between the two media, characterized in that the second medium (106) is enclosed on all sides by the first medium (105) that the means (108) for changing the interface (107) are designed to act on the first and / or second medium (105, 106) and that the means (108) for changing the interface (107) to generate a pressure on the first and / or second medium (105, 106).

9. Optical element according to claim 8, characterized in that the means (108) for changing the interface (107) act on the first and / or second medium (105, 106) such that the curvature of the interface (107) between the first (105) and second (106) medium.

10. Optical element according to one of claims 1 to 9, characterized in that the first medium (46, 66, 90, 105) and / or the second medium (47, 67, 91, 106) is a liquid.

11. Optical element according to one of claims 1 to 10, characterized in that the first medium (46, 66, 90, 105) and / or the second medium (47, 67, 91, 106) is gel-like.

12. Optical element according to claim 10 or 11, characterized in that the second medium (47, 67, 91, 106) is designed in the form of a drop.

13. Optical element according to one of claims 1 to 12, characterized in that the first medium (46, 66, 90, 105) and the second medium (47, 67, 91, 106) have the same density.

14. Optical element according to one of claims 1 to 13, characterized in that the first medium (46, 66, 90, 105) and the second medium (47, 67, 91, 106) have different optical properties.

15. Optical element according to claim 14, characterized in that the first medium (46, 66, 90, 105) and the second medium (47, 67, 91, 106) have different refractive indices.

16. Optical element according to one of claims 1 to 15, characterized in that the spatial fixation of the first (46, 66, 90, 105) and / or second (47, 67, 91, 106) medium within the receiving container (42, 62, 82, 102) by means of fixing means.

17. Optical element according to claim 16, characterized in that the fixing means in the form of a special surface design of the contact surface (48, -68, 88, 89) and / or in the form of a special surface quality of the contact surface (48, 68, 88, 89) are trained.

18. Optical element according to one of claims 1 to 17, characterized in that in the contact surface (48, 68) of the receptacle (42, 62) on which the second medium (47, 67) rests, an opening (52, 74 ) is provided and that the second medium (47, 67) is fixed in the region of the opening (52, 74).

19. Optical element according to one of claims 1 to 18, characterized in that the means (50, 108) for changing the interface (49, 107) are designed as mechanical means.

20. Optical element according to claim 19, characterized in that the mechanical means are designed as a piston device (51, 109) or cylinder device.

21. Optical element according to one of claims 1 to 20, characterized in that the means (70) for changing the interface (69) are in the form of a controllable membrane (71).

22. Optical element according to one of claims 1 to 21, characterized in that the means (50, 70, 108) for changing the interface (s) (49, 69, 92, 93, 107) electrically and / or magnetically and / or can be actuated electromagnetically and / or pneumatically and / or hydraulically and / or piezoelectrically.

23. Optical element according to one of claims 1 to 22, characterized in that it is designed as a lens element or prism element or mirror element.

24. Optical device with variable focal length, comprising a number of optical elements, characterized in that at least one of the optical elements (40, 60, 80, 100) is designed according to one of claims 1 to 23.

25. Use of an optical element (40, 60, 80, 100) according to one of claims 1 to 23 in an optical device with variable focal length and / or with variable spectral splitting and / or with variable beam guidance.

26. Use of an optical element (40, 60, 80, 100) according to one of claims 1 to 23 in a microscope, or an endoscope, or a telescope, or a telescope, or a camera, or a camcorder, or a camera in a cell phone, or a magnifying glass, or a head magnifying glass.