WO2013190454A2

WO2013190454A2 - Customized optical element

Info

Publication number: WO2013190454A2
Application number: PCT/IB2013/054970
Authority: WO
Inventors: Ties Van Bommel; Rifat Ata Mustafa Hikmet
Original assignee: Koninklijke Philips N.V.
Priority date: 2012-06-20
Filing date: 2013-06-18
Publication date: 2013-12-27
Also published as: WO2013190454A3

Abstract

The present invention provides an optical element comprising an enclosure including a liquid. The amount of the liquid in the enclosure is adjustable for adjusting the volume and/or shape of the enclosure. Further, the liquid is polymerisable for fixation of the enclosure at a specific volume and/or shape corresponding to a desired optical property of the optical element. The present invention further provides an optical system comprising such an optical element and at least one light source for emitting light through the element. The light source may for example be selected from a Light Emitting Diode (LED), an Organic Light Emitting Diode (OLED) and a laser diode. The present invention further provides the use of a polymerisable liquid in an optical element for enabling fixation of the shape and/or volume of an enclosure of the element, thereby determining at least one optical property of the optical element.

Description

Customized optical element

BACKGROUND OF THE INVENTION

Generally, several specific optical elements are used in order to obtain a specific shape or collimation of a light beam originating from a light source. However, using several optical elements is often rather clumsy and time consuming. An alternative is the use of a liquid lens, in which a fluid forms a variable lens without any mechanical moving parts. The properties of a liquid lens are varied by controlling the meniscus, i.e. the shape of the surface of the liquid, for example by varying the pressure on the liquid or the interfacial tension acting on the liquid. A liquid lens may also have a membrane that encloses the liquid. In such mechanically tunable liquid lenses, a lens fluid is pumped into or out of the lens enclosure, and the lens membrane expands to form either a concave shape or a convex shape for achieving a desired focus or zoom. However, such a system might have lifetime issues such as leakage.

There is therefore a need in the art for improved or alternative customized optical elements.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improvement of the above techniques and prior art.

The above object is provided according to a first aspect of the invention by an optical element comprising an enclosure including a liquid. The amount of the liquid in the enclosure is adjustable for adjusting the volume and/or shape of the enclosure. Further, the liquid is polymerisable for fixation of the enclosure at a specific volume and/or shape corresponding to a desired optical property of the optical element.

A "polymerizable liquid" refers to a liquid that may be polymerized, i.e.

transferred from a liquid state to a solid state or to a gelled state by means of polymerization. Polymerization may thus involve reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains. The polymerisable liquid may for example be transparent to light, both in the liquid state and in the solid or gelled state. "Fixation of the enclosure" may be an irreversible fixation or a reversible fixation of the enclosure.

The first aspect of the invention uses the understanding that a polymerisable liquid may be used to fixate at least one optical property of an optical element by

polymerizing the liquid within an enclosure of the element. The shape and/or volume of the enclosure is adjustable or selectable and the polymerisable liquid may be in a liquid state while tuning for a specific property of the element by adjusting the shape and/or volume of the enclosure. The tuning may involve changing the amount of polymerisable liquid in the enclosure, which in turn may affect e.g. the thickness of the enclosure and/or the shape of an interface of the enclosure. Once the desired property is found, the liquid may be polymerized, which may lead to fixation of the thickness, or volume, of the enclosure and/or the shape of an interface of the enclosure. The adjustable enclosure comprising a polymerisable liquid thus provides for a customizable shape of the optical element. The first aspect of the invention is advantageous in that it allows for avoiding or at least reducing stability issues, such as leakage of the liquid, during the lifetime of the optical element.

In order words, the first aspect of the invention provides customizable optics that may be for example used with one or several LED sources in order to obtain a desired collimation or beam shape of the light from the LED source(s) that has passed the optics. The invention is also advantageous in that it provides a more reliable optical element.

In embodiments of the first aspect of the invention, the enclosure may be formed by a base and a membrane. As an example, the membrane may be a flexible membrane. The membrane may thus be adapted to deform as a response to an adjustment of the volume and/or shape via an adjustment of the amount of the polymerisable liquid of the enclosure. As an example, the membrane may be adapted to change its curvature as a response to an adjustment in volume of the enclosure. The curvature of the membrane may increase as the volume increases, which means that the membrane may expand to form either a concave or convex shape to achieve e.g. a desired focus or zoom. Hence, a focusing power, or more generally an optical property, of the optical element may be tuned by adjusting the volume of the polymerisable liquid in the enclosure. When the desired focusing power is obtained, the liquid may be polymerized in order to fixate the enclosure of the optical element.

Further, the membrane may be adapted to change its structure as a response to e.g. the shape of the enclosure. Thus, the profile of the membrane, if viewing a cross section of the optical element, may be adjusted by e.g. changing the shape of the enclosure. Further, the base portion may also be a membrane as described above.

Adjusting the volume and/or shape of the enclosure may affect an optical light path of the element. An optical light path refers to a path along which light beams may traverse through the optical element. Thus, by adjusting the volume and/or shape of the enclosure, the length of the optical light path and/or the refractive index of the enclosure may be affected. Further, the shape of the enclosure-membrane interface or the enclosure-base portion interface may be affected by adjusting the volume and/or shape of the enclosure. Affecting the optical light path may thus affect any light passing along the optical light path in terms of collimation, diffraction, color temperature, beam shape etc.

As an example, a base (or base portion) and the membrane may be a part of an optical light path through the element. Thus, a beam of light may travel through the base, enclosure and membrane.

In embodiments of the first aspect of the invention, the optical property of the optical element may be one of a desired color temperature a beam shape or collimation.

Thus, adjusting the volume and/or shape of the enclosure may affect e.g. the desired color temperature, beam shape, collimation of the optical element. The optical element may for example be a lens and adjusting the volume and/or shape of the enclosure may thus affect the focus power of the lens and/or the beam shape of light passing the optical element.

In embodiments of the first aspect of the invention, the enclosure may be adjustable such that a change in the volume and/or shape of the enclosure affects the thickness of the enclosure. This may be achieved by for example bringing extra fluid into the enclosure or exerting pressure or deformation to the enclosure. This may thus affect the length of an optical light path through the element. Consequently, the thickness of the optical element may be tuned by e.g. adjusting the amount or volume of polymerisable liquid in the enclosure.

In embodiments of the first aspect of the invention, the polymerisable liquid may further comprise at least one luminescent compound.

A luminescent compound may for example be a compound that emits light as a response to excitation of light of a specific frequency or wavelength. For example, the luminescent compound may be a fluorescent compound or a phosphorescent compound.

The luminescent compound may for example comprise inorganic phosphor, organic phosphor, Quantum Dots (QDs) or any combination thereof. The polymerisable liquid may comprise several luminescent compounds. As an example, the luminescent compound may comprise (colored) organic luminescent compounds. Examples of luminescent compounds are luminescent compounds based on perylene derivatives. Examples of Lumogens include, but are not limited to, Red f305, Orange f240, Yellow f083, or fl70. Quantum Dots and Quantum Rods may be based on CdSe, CdS, or InP. Examples of inorganic luminescent compounds may be Ce doped YAG (Y3AI5O12) or LuAG (LU3AI5O12). Ce doped YAG may emit yellowish light, and Ce doped LuAG may emit yellow-greenish light. Examples of other suitable luminescent compounds which may emit red light include, but are not limited to EC AS (EC AS, which is

Cai__xAlSiN₃:Eux; with 0<x<l; especially x<0.2) and BSSN (BSSNE, which is

Ba₂-_x-_zMxSi5-yAl_yN₈-yOy:Eu_z (M=Sr, Ca; 0<x<l, especially x<0.2; 0<y<4, 0.0005<z<0.05)).

If the polymerisable liquid comprises a luminescent compound, the thickness of the enclosure may affect the output color of light passing through the optical element, thus affecting the color temperature of the optical element. Thus, the desired color temperature of the optical element may be tuned by adjusting the volume of the enclosure and when the desired color temperature is found, the thickness of the enclosure may be fixated by polymerizing the liquid in the enclosure.

In embodiments of the first aspect of the invention, the polymerisable liquid may be adapted to polymerize upon exposure to light or heat.

In other words, the step of polymerizing the liquid may comprise exposing the liquid to light or heat to initiate a polymerization reaction.

As an example, the polymerisable liquid may comprise a photo initiator. The photo initiators may be Ingacure 369, Irgacure 651 or Irgacure 184. The photo initiator may be adapted to initiate the polymerization reaction as a response to irradiation with light comprising a blue or ultraviolet component. The photo initiators may alternatively be adapted to polymerize as a response to irradiation with sun light.

The composition may contain 0.05-5% of the photo initiator, such as 0.1-2% of the photo initiator.

Photo initiated radical polymerization may be the most convenient method of polymerization. In such a method, an acrylate may be used, for example ethoxylated bisphenol-A diacrylate containing a photo initiator Irgacure 651. Such a material may be polymerized under UV radiation with a wavelength of about 369 nm. In the same way, bisphenol-A epoxy resin may be provided with a cationic photo initiator, such as Bis(alkyl (C=10)phenyl iodonium hexafluorophosphate. This material may also be polymerized by UV radiation.

As mentioned above, the polymerisable liquid may alternatively, or in addition, be adapted to polymerize upon exposure to heat, i.e. the polymerization may be thermally initiated, in which case a thermal initiator may be used.

The polymerisable liquid may comprise multifunctional monomers that may be polymerized. The use of multifunctional monomers may lead to the formation of cross- linked polymer networks. However, monomers of the polymerisable liquid may also be mono functional, in which case a linear polymer may be obtained.

Consequently, in embodiments of the first aspect of the invention, the polymerisable liquid may comprise an acrylate, methacrylate, a vinyl monomer, an epoxy, a thiolene system, polyurethanes or silicones. For example, the polymerisable liquid may comprise polyethyleneglycol diacrylate, such as polyethyleneglycol (400) diacrylate.

In embodiments of the first aspect of the invention, the enclosure may be arranged to be in liquid contact with a liquid reservoir, which means that the reservoir may comprise control means for transferring the polymerisable liquid from the reservoir to the enclosure, or vice versa.

The reservoir may thus be used for increasing or decreasing the amount of polymerisable liquid in the enclosure. The control means may thus be used for transferring liquid from the reservoir to the enclosure and/or from the enclosure to the reservoir in order to adjust the volume and/or shape of the enclosure.

The invention further relates to an optical element according to the first aspect of the invention in which the polymerized liquid has been polymerized. Thus, as a configuration of the first aspect of the invention, there is provided an optical element comprising an enclosure including a polymerized liquid. The polymerized liquid fixates the enclosure at a specific volume and/or shape corresponding to a desired optical property of the optical element.

As already mentioned above, the present invention is advantageous in that a more stable optical element is provided.

In embodiments of the present configuration of the first aspect of the invention, the enclosure may be formed by a base and a membrane.

Further, in embodiments of the present configuration of the first aspect of the invention, the optical property of the optical element may be one of a desired color temperature, a beam shape or collimation. In embodiments of the present configuration of the first aspect of the invention,

the polymerized liquid further comprises at least one luminescent compound. As an example, the at least one luminescent compound may be selected from the group consisting of inorganic phosphor, organic phosphor, Quantum Dots (QDs) or a combination thereof.

Further, in embodiments of the present configuration of the first aspect of the invention, the polymerized liquid comprises a (metha)acrylate, an epoxy, a vinylether monomer or a thiolen system.

The optical elements of the present invention may further comprise a light protective layer that protects the enclosure from light from the outside of the element. Thus, any luminescent compounds in the polymerisable or polymerized liquid in the enclosure may be protected by the light protective layer. This may also be advantageous if the polymerized liquid is adapted to polymerize upon irradiation with sun light, i.e. the protective layer may aid in controlling the polymerization reaction.

The light protective layer may for example be arranged on a membrane of the enclosure.

According to embodiments of the first aspect of the invention, there is provided an optical system comprising an optical element described in any one of the preceding embodiments and at least one light source for emitting light through the element.

The light source may be arranged for emitting light through the enclosure of the element, along an optical light path of the optical element. As an example, the light source may be selected from a Light Emitting Diode (LED), an Organic Light Emitting Diode (OLED), a laser diode, or any combination thereof.

As an example, the light source may emit blue light, but it may also emit any other color such as green or red. Further, the light source may emit UV or violet light.

The light from the light source may for example be guided into the enclosure of the optical element through a light guide.

The light source of the system may thus be used for polymerizing the liquid if the polymerization of the liquid is to be initiated by irradiation with light. Further, heat from the light source may be used to initiate the polymerization if the polymerization of the liquid is to be initiated by an increase in temperature.

The optical system may for example be a lighting system having one or several LEDs or OLEDs as light source(s). Further, the optical system may further comprise a sensor for measuring an optical property of the light from the at least one light source that has passed through the optical element.

As an example, if the optical system is a lighting system, a sensor such as a light color sensor may be used to measure the Correlated Color Temperature (CCT) of the lighting system. The CCT of the optical system may vary depending on the volume or thickness of the enclosure, which means that the CCT may be monitored as the thickness varies, which thus allows for tuning the desired CCT. When the desired CCT has been found, polymerization may be initiated, thereby fixing the volume or thickness of the optical element of the system to the desired CCT. Thus, the result from the sensor may be used to customize the shape of the enclosure of the optical element.

Further, the system may also comprise a controller for controlling or initiating the polymerization of the polymerisable liquid when a desired optical property has been measured.

The controller may thus be connected to the sensor and initiate polymerization, e.g. by controlling the light intensity or rather the wavelength of the light source if the liquid is polymerisable upon irradiation with light, when a desired property of the light that has passed through the element has been obtained.

According to an embodiment of the first aspect of the invention, there is provided a light fixture or luminaire comprising an optical element or an optical system according to any one of the preceding embodiments.

As an example, the optical element or system may be used in a light tile.

According to a second aspect of the invention, there is provided a method for producing an optical element, wherein the element comprises an enclosure including a polymerized liquid. The method comprises the steps of:

a) forming an enclosure including a polymerisable liquid;

b) adjusting the amount of the liquid in the enclosure for adjusting the volume and/or shape of the enclosure; and

c) polymerizing the polymerisable liquid for fixating the enclosure at a specific volume and/or shape corresponding to a desired optical property of the optical element.

The terms and definitions used in the second aspect of the invention are the same as discussed in relation to the first aspect of the invention above. In analogy with the first aspect of the invention above, a method according to the second aspect provides for fixating an optical property of a tunable or customizable optical element by polymerizing a polymerisable liquid.

It will be appreciated that the features of the embodiments described with reference to the first aspect of the invention are also combinable with the method as defined in accordance with the second aspect of the invention.

In embodiments of the second aspect of the invention, the at least one optical property may be the Correlated Color Temperature (CCT) of the optical element.

As a third aspect of the invention, there is provided the use of a polymerisable liquid in an optical element for enabling fixation of the shape and/or volume of an enclosure of the element, thereby determining at least one optical property of the optical element.

As described in relation to the first and second aspects above, fixation of the shape and/or volume comprises polymerizing the polymerisable liquid. The third aspect, in analogy with the first and second aspects above, provides for fixating an optical property of a tunable optical element by polymerizing a polymerisable liquid.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those explicitly described in the following. BRIEF DESCRIPTION OF THE DRAWINGS

The aspects of the present invention will now be described in more detail, with reference to the appended drawings showing currently preferred embodiments of the invention.

Fig. 1 shows an embodiment of an optical element connected to a liquid reservoir in accordance with an embodiment of the present invention.

Fig. 2 demonstrates how the shape of the enclosure of the optical element may be fixated and how this may affect the optical properties of the element.

Fig. 3 shows examples on how the shape or thickness of the enclosure may be varied.

Fig. 4 shows how a light protective layer may be used to protect e.g.

luminescent compounds in the enclosure.

Fig. 5 shows how a sensor may be used to control optical properties of an optical element.

Fig. 6 shows how an optical element may be used together with a laser. Fig. 7 shows results of the CCT of an optical element measured as a function of the thickness of the enclosure.

DETAILED DESCRIPTION

Figs, la and lb illustrate an embodiment of an optical element 1 of the present disclosure. The element comprises a base portion 3 and a flexible membrane 4, between which an enclosure 2 resides, or together forming the enclosure 2. The enclosure 2 is filled with a liquid comprising polymerisable monomers. The base portion 3, enclosure 2 and the membrane 4 are optically transparent, such that an optical light path, illustrated by e.g. arrow a, is formed through the element 1. The enclosure is connected to a reservoir 5 comprising the polymerisable liquid. The liquid in the reservoir may be transferred to and from the enclosure 2 by means of pushing or pulling the piston 6. Thus, by pushing down the piston 6, more liquid is transferred to the enclosure 2, which further increases the volume of the enclosure 2 as the flexible membrane 4 bends outward. The optical light path is affected by the volume of the enclosure 2 and/or the shape of the membrane 4, i.e. the optical light path is different when more liquid resides in the enclosure (Fig. lb) compared to when less liquid resides in the enclosure (Fig. la). As an example, light travelling along the optical path may have a different beam shape, such as being more collimated, when leaving the element 1 of Fig. la compared to leaving the element of Fig. lb.

Fig. 2a-f further illustrate how the shape of the enclosure 2 in an optical element 1 may be fixated. The element 1 shown in Figs. 2a-f is similar to the element as described in relation to Fig. 1. Fig. 2a and 2b illustrate how the membrane 4 expands as the volume of the enclosure 2 increases. Fig. 2c further shows a light source 7, for example one or several LEDs, that is used to irradiate the optical element through the base portion 3. The polymerisable liquid in enclosure 2 starts polymerizing by radiation denoted "b" from the light source 7. The polymerisable liquid may thus comprise photo initiators and suitable monomers with the capability of forming a solid polymer or a gelled state upon

polymerization. However, the polymerisable liquid may also comprise initiators that initiate the polymerization reaction from the heat of the light sources 7. After the polymerization step of Fig. 2c, the shape and volume of the enclosure 2 is fixated, and e.g. the focusing power of the element 1 is fixed, to the element as illustrated in Fig. 2d. Thus, the beam shape of the light from an external light source 8 is affected when passing optical element 1.

In Fig. 2e, the enclosure 2 of the optical element 1 is fixated by the light source 7 when less liquid is present in the enclosure 2 as compared to the situation shown in Fig. 2c, and the solidified element 1 in Fig. 2f thus has different optical properties compared to the solidified element of Fig. 2d, as illustrated by the arrows representing the light beams passing through the optical element (which arrows point differently in Fig. 2d as compared to Fig. 2f). Thus, light from a light source 8 may have a different collimation after passing the element of Fig. 2d compared to the collimation after passing through the element of Fig. 2f. Accordingly, there is provided an optical element with customizable optical property.

Figs. 3a-c further illustrate three different optical elements of the present disclosure and how the shape and volume may be affected upon changing the volume of the liquid in the enclosure 2. In Figs. 3a-3c, the volume in the enclosure 2 increases from left to right. In Fig. 3a, only the thickness of the optical element increases as the volume increases. If the enclosure comprises a luminescent material, the CCT of the optical element may be affected by a change in the thickness. Fig. 3b illustrates an optical element similar to the element described in Figs 1 and 2, i.e. an element having a flexible membrane such that the shape of the membrane is affected. Thus, by increasing the volume in the enclosure 2, the membrane 4 bends outward. Fig. 3c describes an embodiment in which the surface shape or surface structure of the membrane 4 is affected by the volume of the polymerisable liquid of the enclosure 2. Thus, the examples shown in Figs. 3a-c demonstrate that a variety of different shapes of fixated optical elements may be obtained by polymerizing the liquid at different enclosure volumes.

Fig. 4 shows an example of an optical device 9 comprising an optical element

1 of the present invention. In this example, there are light sources in the form of LEDs 13 arranged in the base portion 3. Further, the base portion 3 has sides 12 that seals the enclosure 2. The enclosure 2 comprises a polymerized liquid having luminescent compounds. A light protective layer 11 is arranged on top of a membrane residing at the top of the enclosure 2 so as to protect the luminescent compounds of the enclosure 2. The layer 11 may thus protect the enclosure from external light, such as sun light, which increases the lifetime of the luminescent compounds and thereby the lifetime of the optical device 9.

Fig. 5 shows an example of an optical system comprising an optical element 1 of the present disclosure. The element is arranged in cap/reflector 17. Light sources 13 are arranged below the optical element 1. In this example, the polymerisable liquid in the enclosure of the optical element 1 has not been polymerized yet and the liquid further comprises luminescent compounds. A light sensor 15 is arranged to measure the light from the light sources that has passed through the element 1. The light sensor 15 may be a light color sensor that measures the CCT of the light from the optical element 1. A controller 16 is used to control the shape or volume of the enclosure in the optical element and to read the sensor output, e.g. the measured CCT. The controller 16 is further arranged to initiate polymerization of the polymerisable liquid of the optical element 1 when e.g. a desired CCT is measured. Hence, the controller 15 is arranged to control the light output from the light sources 13, for example to increase the intensity or change the wavelength of the light from the light sources 13 in order to start the polymerization if photo initiators are present in the polymerisable liquid. Thus, with the configuration shown in Fig. 5, the CCT of the optical device may be measured as a response to adjusting the shape or volume of the enclosure in the optical element 1 , and when the desired CCT has been obtained, the polymerisable liquid may be polymerized so as to fix the CCT of the optical element 1.

Fig 6 shows a system 18 in which an optical element 22 is applied together with a laser diode 19. The laser beam 20 from the laser diode 19 is diffracted by a diffraction element 21 and then enters the optical element 22. The output laser light through the element 22 may be measured and, by changing the shape and/or volume of the enclosure of the optical element 22, the laser light travelling through the element may be affected in different ways as illustrated above. When the desired property of the outgoing laser light, i.e. laser light that has passed the element 22, is obtained, the liquid may be polymerized to fix the optical property of the system 18. Experimental example

An experiment was conducted to show how the correlated color temperature (CCT) of an optical element of the present disclosure changes with the thickness of the enclosure. Fig. 7 shows the result of the CCT points of an organic phosphor element containing 0.0075 wt% Lumogen Red F305, 0.0175 wt% Lumogen Orange F240 and 0.075 wt% Lumogen Yellow F083 with a layer thickness, i.e. a thickness of the enclosure, of

108 μιη (4Μ(7.5Ιί-17.50-75 Y)-D), 135 μιη (5M(7.5R-17.50-75Y)-D), 162 μιη (6M(7.5R- 17.50-75 Y)-D), 189 μιη (7M(7.5R-17.50-75 Y)-D) and 216 μιη (8M(7.5R-17.50-75Y)-D). In this example the color is shifted along the BBL, which is preferred in most applications. However, it is also to be understood that the color point may be shifted in any other direction.

This experiment clearly demonstrates that the present invention allows a user to tune the CCT of the optical element and select a CCT along the black body line (BBL) simply by controlling the thickness of the layer and subsequently fixing the CCT of the light source by polymerizing the liquid of the enclosure. Even though the invention has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art. The described embodiments are therefore not intended to limit the scope of the invention, as defined by the appended claims.

Claims

CLAIMS:

1. An optical element comprising an enclosure including a liquid, wherein the amount of the liquid in the enclosure is adjustable for adjusting the volume and/or shape of the enclosure, the liquid being polymerisable for fixation of the enclosure at a specific volume and/or shape corresponding to a desired optical property of said optical element.

2. The optical element according to claim 1, wherein the enclosure is formed by a base and a membrane.

3. The optical element according to claim 1 or 2, wherein the optical property of said optical element is one of a desired color temperature, a beam shape or collimation.

4. The optical element according to any previous claim, wherein the

polymerisable liquid further comprises at least one luminescent compound.

5. The optical element according to claim 4, wherein the at least one luminescent compound is selected from the group consisting of inorganic phosphor, organic phosphor, Quantum Dots (QDs) or a combination thereof.

6. The optical element according to any previous claim, wherein the

polymerisable liquid is adapted to polymerize upon exposure to light or heat.

7. The optical element according to claim 6, wherein the polymerisable liquid comprises a photo initiator.

8. The optical element according to any previous claim, wherein the

polymerisable liquid comprises an acrylate, methacrylate, a vinyl monomer, an epoxy, a thiolene system, polyurethanes or silicones.

9. The optical element according to any previous claim, wherein the enclosure is arranged to be in liquid contact with a liquid reservoir, said reservoir comprising control means for transferring said polymerisable liquid from said reservoir to said enclosure or vice versa.

10. An optical element comprising an enclosure including a polymerized liquid, wherein the polymerized liquid fixates the enclosure at a specific volume and/or shape corresponding to a desired optical property of said optical element.

11. An optical system comprising an optical element according to one of the previous claims and at least one light source for emitting light through said element.

12. An optical system according to claim 11, wherein the at least one light source is selected from a Light Emitting Diode (LED), an Organic Light Emitting Diode (OLED), a laser diode, or any combination thereof.

13. An optical system according to claim 11 or 12, further comprising a sensor for measuring an optical property of the light from said at least one light source that has passed through said optical element.

14. Use of a polymerisable liquid in an optical element for enabling fixation of the shape and/or volume of an enclosure of said element, thereby determining at least one optical property of said optical element.

15. A method for producing an optical element, wherein the element comprises an enclosure including a polymerized liquid. The method comprises the steps of:

a) forming an enclosure including a polymerisable liquid;