WO1999041624A1

WO1999041624A1 - A device comprising an optical body

Info

Publication number: WO1999041624A1
Application number: PCT/SE1999/000215
Authority: WO
Inventors: Håkan BONDS
Original assignee: Bonds Haakan
Priority date: 1998-02-17
Filing date: 1999-02-17
Publication date: 1999-08-19
Also published as: SE9800460D0; SE511727C2; SE9800460L

Abstract

The present invention comprises a device comprising an optical body, which is arranged to refract the light (3) passing through the body and which comprises at least one first surface (2) arranged to receive the light (3) from a surrounding space, an inner cavity arranged to contain a liquid, transparent medium (6), and a second surface (4) arranged to emit the light (3) to the surrounding space. The optical body comprises a casing (5) formed by a transparent wall, having a significantly thinner wall thickness than the dimension of the optical body and determining the outer shape of the optical body, wherein said wall comprises said first (2) and second (4) surfaces and forms an essentially closed unit.

Description

A device comprising an optical body

THE FIELD OF THE INVENTION AND PRIOR ART

The present invention refers to a device comprising an optical body, which is arranged to refract the light passing through the body and which comprises at least one first surface arranged to receive the light from a surrounding space, an inner cavity arranged to contain a liquid, transparent medium, and a second surface arranged to emit the light to the surrounding space.

Devices comprising optical bodies are previously known and employed inter alia in optical instruments, such as cameras, binoculars and microscopes. Optical bodies are usually manufactured in a solid glass material. The manufacture of large such optical bodies requires high precision and accuracy so that the glass body becomes fully transparent and without internal defects. Such a larger optical body will therefore be expensive to manufacture, heavy to transport and requires very careful handling or a sophisticated chock absorbing packing in order not to be damaged during such a transport. Moreover, conventional optical bodies of the type mentioned above also have the disadvantage that the refractive properties may not be changed. If one would like to change the refractive properties, the optical body has to be replaced by another optical body having the desired refractive properties.

From US 5 436 766, US 5363 127, US 5 182 585 and US 5 774 273, devices are known comprises optical bodies, which comprise inner cavities arranged to contain a liquid, transparent medium. These optical bodies are relatively small and have a relatively complicated construction including many different parts.

From DE 296 12 864 U1 , WO97/07994 A1 , US 4 020 580 A and US 4 085 533 A, devices are previously known, which comprise an outer casing forming an inner cavity arranged to contain a liquid, transparent medium. These devices are not arranged to work as an optical body arranged to refract the light passing through the body.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a device comprising an optical body which may be manufactured with large dimensions at a high quality and to low expenses. Another object is to enable the changing of the refractive properties of an optical body.

This object is obtained by the device initially defined and characterised in that the optical body comprises a casing formed by a transparent wall, having a significantly thinner wall thickness than the dimension of the optical body and determining the outer shape of the optical body, wherein said wall comprises said first and second surfaces and forms an essentially closed unit. By this design large optical bodies having a homogeneous body without any defects may be obtained to low costs. The liquid medium contained may for instance be water, distilled water, a salt solution, ethanol or any other transparent liquid having the desired refractory properties. By replacing the liquid medium by another liquid medium the refractive properties of the optical body may be changed in an easy manner. By a relatively thin casing in relation to the thickness of the optical body, the refractive properties of the optical body are essentially the same as the refractive properties of the liquid medium. Said casing forms an essentially closed unit and thereby, the liquid medium contained may not be lost from the optical body if the latter is subjected to movements. Preferably the wall has an essentially uniform thickness. Thereby, a simple and inexpensive casing may be manufactured. According to an embodiment of the invention, means are arranged to enable the supply and discharge of the liquid medium. Preferably, said means is arranged to enable a complete emptying of the liquid medium. Thereby, it is possible to replace one liquid medium by another liquid medium. Furthermore, a completely emptied casing without any liquid medium is easy to handle and transport. Said means may comprise a passage arranged to extend through the casing and closeable by a closure member. In its most simple form, said passage may be a hole in the casing which is closeable by means of a closing member adapted to fit in the hole. In connection with larger optical bodies, it is especially advantageous to discharge the liquid medium from the optical body, because it makes the large optical body much lighter and thereby more easy to handle during transportation. During such a transportation the optical body may be enclosed in a container filled with pressurised air. Thereby, damage of the optical body during the transportation is prevented. Said means may also be employed when a first liquid medium is to be replaced by a second liquid medium having different refractive properties. The liquid medium contained may be chosen to have essentially identical refractive properties as the material of the casing. Thereby, an optical body having uniform refractive properties is obtained in the same manner as a homogeneous optical body produced in for instance the material of the casing.

According to a preferred embodiment of the invention, the casing is manufactured in a rigid material, which includes any non-flexible transparent material such as a glass material or a plastic material. In case of large optical bodies, these materials must be provided to withstand the weight of the liquid contained. Suitable materials may thereby be plexiglass or armoured glass. In case of smaller optical bodies more simple plastics and glass material may be employed.

According to a further preferred embodiment of the invention, the casing consists of a material having elastic properties. Such a material may be a transparent plastic material. Advantageously, said means are arranged to supply a liquid medium in a variable quantity to said cavity, wherein the first and second surfaces of the casing are arranged to change elastically the outer shape and thus the refractive properties of the body. For instance, an optical body having a casing with first and second surfaces which are convex may, by the supply of a further liquid medium, form a lens having convex surfaces with a larger curvature than in case of a smaller liquid quantity. Said means may comprise a pump device which is arranged to control the supply of the liquid medium to the cavity of the optical body. By controlling the pump device, the liquid quantity in the optical body may be controlled and thereby the diffraction of the optical body may be varied in a very easy manner.

According to a further preferred embodiment of the invention, the optical body may form a lens having convex or concave first and second surfaces or a prism having first and second plane surfaces forming an angle to each other. Such a positive lens may be manufactured of a first wall member forming a part of a sphere and a second wall member forming a part of a sphere, wherein the first and second walls are connected together along their peripheral portions for forming the casing.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following preferred embodiments of the invention are described as examples with reference to the drawings attached, in which

Fig 1 discloses a cross-sectional view through an optical body in the form a lens, according to a first embodiment of the invention, Fig 2 discloses a second embodiment of the invention in the form of a prism, and Fig 3 discloses a third embodiment of the invention where the casing comprises a material having elastic properties. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In Fig 1 , a first embodiment of the invention is disclosed, which comprises an optical body forming a lens 1. This lens 1 comprises a first surface 2, which is arranged to receive light 3 from a surrounding space and a second surface 4 which is arranged to emit light 3 to the surrounding space. The lens 1 comprises a casing 5 which forms the outer shape of the lens and said first 2 and second 4 surfaces. The casing 5 forms an inner cavity which is arranged to contain a liquid transparent medium 6. The lens 1 comprises a hole 7 in the casing 5 for enabling the supply and the discharge of the liquid medium 6. The hole 7 is closeable by means of a closing member 8 so that the liquid medium 6 contained within the casing is prevented from flowing out of the casing 5. The casing 5 is in this case manufactured as a unit of a rigid material, which is transparent and preferably made of glass or plastic material. The casing 5 is relatively thin in relation to the thickness of the lens 1 and has an essentially uniform wall thickness. For example, during transportation it is preferable to discharge the liquid medium 6 from the lens 1. Thereby, the weight of the lens 1 during the transportation is essentially reduced. A lens 1 without the liquid medium 6 may have a weight below 10% of the weight with the liquid medium 6. Large optical bodies may in this case have a relatively low weight. Thereby, the risk of damaging the lens 1 during transportation is essentially reduced. In Fig 1 , the lens 1 is shown in an active position supported by means of a support S, extending around the periphery of the lens 1. Such a positive lens 1 may be manufactured of a first wall member 5a forming a part of a sphere and a second wall member 5b forming a part of a sphere, wherein the first and second walls 5a, 5b are connected together along their peripheral portions 5c, 5d by, for example, an adhesive in order to form the casing 5.

The incoming light 3 is refracted at the first and second surfaces 2, 4 during its passage through the lens 1. Since the lens 1 is positive, parallel rays incident on the lens 1 will converge to a focal point 9. During the passage of the light 3 through the lens 1 further diffraction of the light 3 are obtained when the light passes from the first wall 5a of the casing 5 to the liquid medium 6 contained within the casing 5 and from this medium 6 to the second wall 5b of the casing 5. These diffractions depend on the difference in the refractive index between the material of the first 5a and second 5b walls of the casing 5 and liquid medium 6. By replacing one liquid medium 6 with another, the refractive properties of the lens may thus be changed, so that the focal point 9 in the example disclosed may be displaced in any direction.

Fig 2 discloses a second embodiment of the invention, which comprises an optical body forming a prism 10. Incoming light 3 will be refracted at a plane surface 2 when entering the prism 10 and refracted at its exit from the prism 10 at a second plane surface 4. The prism 10 is formed by the casing 5 enclosing a liquid, transparent medium 6. The casing 5 is rigid and comprises a glass or plastic material of a relatively thin thickness. The casing 5 may also in this case have an essentially uniform wall thickness. The prism 10 comprises a hole 7 provided in the casing 5 for the supply and the discharge of the liquid medium 6. Also in this case, the refractive properties of the prism 10 may be varied depending on which liquid medium is contained in the casing 5.

Fig 3 discloses a third embodiment of the invention. The casing 5 consists in this case of a material having elastic properties, preferably a plastic material. By supplying the liquid medium 6 in a variable quantity to the cavity of the casing 5, the first 2 and second 4 surfaces of the casing change the outer shape and thereby the refractive properties of the lens 11. If required, the casing 5 may in this embodiment have a variable wall thickness and thereby variable elastic properties along the first 2 and second 4 surfaces, so that the lens 1 may obtain a desired shape during the supply and discharge of the liquid medium 6. In Fig 3, the casing 5 of the lens 11 is disclosed by continuous lines in a first position and by broken lines 5' in a second position. In order to control the liquid supply to the lens 11 , the device comprises a pump device 12 which is arranged to pump liquid 6 from a liquid container 13 through a conduit 14 and through a one-way valve 15 to the interior of the lens 1 1 in order to increase the liquid quantity and the pressure within the lens 11 in such a manner that its first 2 and second 4 surfaces will take a more curved shape. The lens 11 according to the broken lines 5' will thus have a shorter focal length than the lens 1 1 according to the continuous line 5. In order to decrease the liquid quantity and the pressure in the lens 11 and thereby obtain a smaller thickness of the lens 11 , a valve 16 is provided, which in an open position permits the liquid 6 to be conveyed through a conduit 17 from the inner cavity of the lens 11 and possibly back to the liquid container 13. The valve 16 may be operable in such a manner that the quantity of liquid 6 in the lens 11 in a very precise manner may be decreased by opening and closing the valve 16.

The invention is not limited to the embodiments described above but may be varied freely within the scope of the claims. For instance, other lenses than biconvex lenses may be utilized, e g negative lenses or positive or negative meniscus lenses.

The invention is also not limited to be employed in optical instrument but may of course also be used as decorative elements in connection with furnishing and architecture since large, water- filled lenses are very beautiful.

Claims

8Claims

1. A device comprising an optical body, which is arranged to refract the light (3) passing through the body and which comprises at least one first surface (2) arranged to receive the light (3) from a surrounding space, an inner cavity arranged to contain a liquid, transparent medium (6), and a second surface (4) arranged to emit the light (3) to the surrounding space, characterised in that the optical body comprises a casing (5) formed by a transparent wall, having a significantly thinner wall thickness than the dimension of the optical body and determining the outer shape of the optical body, wherein said wall comprises said first (2) and second (4) surfaces and forms an essentially closed unit.

2. A device according to claim 1 , characterised in that the wall has an essentially uniform wall thickness.

3. A device according to claim 1 or 2, characterised in it comprises means arranged to enable the supply and the discharge of the liquid medium (6).

4. A device according to claim 3, characterised in that said means is arranged to enable a complete emptying of the liquid medium (6).

5. A device according to claim 3 or 4, characterised in that said means comprises a passage arranged to extend through the casing (5) and closeable by a closure member.

6. A device according to any one of the preceding claims, characterised in that the casing (5) is at least partly manufactured in a material having essentially identical refractive properties as the liquid medium (6) contained within the inner cavity.

7. A device according to any one of the preceding claims, characterised in that the casing (5) is manufactured in a rigid material.

8. A device according to claim 6, characterised in that the casing (5) is manufactured in a glass material.

9. A device according to claim 7, characterised in that the casing (5) is manufactured in a plastic material.

10. A device according to any one of the preceding claims, characterised in that the casing consists of a material having elastic properties.

11. A device according to claim 3 and 10, characterised in that said means is arranged to supply the liquid medium (6) in a variable quantity to said cavity, wherein the first (2) and second (4) surfaces of the casing (5) are arranged to change elastically their shape and thus the refractive properties of the body.

12. A device according to claim 11 , characterised in that said means comprises a pump device (12) arranged to control the supply of the liquid medium to the cavity of the optical body.

13. A device according to any one of the preceding claims, characterised in that the optical body forms a lens (1).

14. A device according to claim 13, characterised in that the lens (1 ) is manufactured of a first wall member forming a part of a sphere and a second wall member forming a part of a sphere, wherein the first and second wall members are connected together at their peripheral portions.

15. A device according to any one of the preceding claims, characterised in that the optical body forms a prism (10).