WO2016095927A1

WO2016095927A1 - Integrated optical device

Info

Publication number: WO2016095927A1
Application number: PCT/DK2015/050401
Authority: WO
Inventors: Peter RAABY; Andrew Rafael BAÑAS; Jesper GLÜCKSTAD
Original assignee: Danmarks Tekniske Universitet
Priority date: 2014-12-16
Filing date: 2015-12-16
Publication date: 2016-06-23

Abstract

The invention relates to an integrated optical device. The device has a common optical axis and comprises an input phase mask section, an input focusing section having a focal length ƒ₁, and a phase contrast filter section. The device is configured such that either at least the input focusing section and the phase contrast filter section; or at least the input phase mask section and the input focusing section are integrally formed in an integrated optical element. Furthermore, the phase contrast filter section is arranged in an axial distance substantially equal to the focal length from the input focusing section. The invention further relates to a method of shaping electromagnetic radiation.

Description

INTEGRATED OPTICAL DEVICE

FIELD OF THE INVENTION

The present invention relates to an integrated optical device and a method of shaping electromagnetic radiation. More specifically, the inventive device and method are useful in connection with the generalized phase contrast (GPC) method.

BACKGROUND OF THE INVENTION

Shaping of light, or electromagnetic radiation in general, is important for a vast number of applications from science and R&D, such as biomedical imaging, microscopy, neurophotonics; over illumination and lighting, such as automotive and street lights, security, entertainment, and advertising; to industrial applications such as marking, cutting and welding.

Simple shaping may e.g. be achieved by amplitude masking, by simply blocking parts of light. However, in this way, the blocked radiation is basically lost, leading to a low optical efficiency.

Alternatively, diffractive approaches, such as holograms, may be used, as e.g. known from popular laser pointers with shaped output, often in the form of user- exchangeable elements in the beam output. However, this requires a coherent electromagnetic input, i.e. a laser, that is Fourier or Fresnel transformed and therefore generally results in intensity noise at the output (known as speckles). To be light efficient, holograms in general need a plurality of phase levels.

The generalized phase contrast (GPC) method has been pioneered by the present applicant, and is described e.g. in US patent no. 6,011,874 and European patent EP0830632. By forming a common-path interferometer (CPI) in a 4f- configuration, a phase-only input variation may be translated into an intensity variation at the output. GPC is inherently speckle-free due to the one-to-one pixel mapping and only needs binary phase to operate light efficiently. Hence, an improved shaping of electromagnetic radiation would be advantageous, and in particular a more efficient and/or reliable device with a high output quality would be advantageous. OBJECT OF THE INVENTION

An object of the present invention is to provide an alternative to the prior art.

Especially, it may be seen as an object to provide an optical device that makes manufacturing of a system for shaping electromagnetic radiation easier and cheaper. It is seen as a further object that the system is more mechanical stable and/or that the form factor will go down.

In particular, it may be seen as a further object of the present invention to provide an integrated optical device that solves the above mentioned problems of the prior art with speckles and/or low light power efficiency.

SUMMARY OF THE INVENTION Thus, the above-described object and several other objects are intended to be obtained in a first aspect of the invention by providing an integrated optical device comprising along an optical axis: an input phase mask section, an input focusing section having a focal length f_lr and a phase contrast filter section. The device is configured such that either at least the input focusing section and the phase contrast filter section; or at least the input phase mask section and the input focusing section are integrally formed in an integrated optical element.

Furthermore, the phase contrast filter section is arranged in an axial distance substantially equal to the focal length from the input focusing section. In this way, a particularly compact and rugged device functioning according to the Generalized Phase Contrast method may be realized. More specifically, a phase image imposed by the input phase mask section is optically Fourier transformed by the input focusing section, given a spatially dependent phase change by the phase contrast filter section (e.g. a phase shift to a central part of the focused field), and allowed to diverge again so as to interfere with a reference part of an input field, thus forming a common-path interferometer (CPI). In this way, the far field from the device will project an intensity image, as generated by the phase image. Since no intensity filter is used in the optical path to generate the output image, a very high coupling efficiency may be achieved from an input of the device to the output. The input phase mask section may comprise multiple levels of phase change, thus enabling multi-level intensities ("grey-scale") at the output intensity image or a uniform "flat" intensity level compensating the case where a single level phase mask would otherwise give a non-uniform output intensity. Since the input phase mask section determines the intensity image formed, arbitrary shapes may be generated in the intensity image by appropriate choice of the input phase variation.

More than one integrated optical device may be arranged in a parallel fashion, for instance each being adapted for different electromagnetic frequencies. In this way, an RGB-device or similar may be achieved in an efficient and compact configuration.

In some prior art devices, separate, discrete optical devices have been integrated to provide GPC methods. These separate, discrete devices have been

manufactured separately and then moulded into a common carrier to form mechanically stable devices, as in "State-of-the-art in Generalized Phase Contrast driven optical micro-manipulation" (Optical Trapping and Optical

Micromanipulation, Proceedings of SPIE Vil. 5514, p.117). In an embodiment of the inventive device, the input phase mask, the input focusing section, and the phase contrast filter are not just integrated as described above. They are instead formed integrally in the integrated optical element. In this way, a particularly mechanically stable device may be achieved, since internal alignment of the different sections is provided at the time of manufacture, and no movement is possible (e.g. due to vibrations). In some embodiments, the integrally formed integrated optical device is manufactured as a moulded polymer device, which is advantageous for high volume production. It will be apparent from the drawings that internal reflections between the different sections, e.g. due to Fresnel reflection, are reduced by due to the lower number of surfaces within the device. This is another important benefit of the present invention. Polymers may include silicone-based materials, PMMA, TOPAS, or other types of optical polymers. Another manufacturing option is diamond turning which has an advantage in making new designs or custom specifications in the phase mask, focusing and PCF since moulds do not have to be created first. Obviously, a drawback is that the fabrication speed is relatively low.

In an embodiment of the inventive device, the integrated optical element comprises an optical material, the optical material being optically transparent for electromagnetic radiation having a frequency around a chosen design frequency.

Throughout this text, the term "optical" is to be understood in a broad sense, i.e to include frequencies in the electromagnetic spectrum, i.e. the gamma frequency range, the ultraviolet range, the visible range, the infrared range, the far infrared range, the X-ray range, the microwave range, the HF (high frequency) range, etc. Therefore, choice of optical material for forming the device should reflect the design frequency for which the particular device is desired to function.

In an embodiment, the optical material is selected from the group comprising glass and polymers.

In an embodiment of the inventive device, the input phase mask section comprises a phase-only spatial light modulator, SLM, device configurable for providing an input phase change corresponding to an output image to be generated. In this way, a dynamic output image may be generated with a high optical efficiency, since no intensity filter is used.

In an embodiment of the inventive device, the phase-only SLM comprises a liquid crystal on silicon, LCoS, device. LCoS devices of a reflective configuration may be used with the integrated optical device according to the invention, and are for instance attractive in laboratory systems where the present invention potentially provides improved alignment stability and/or reduced optical losses, when compared to bulk optics realizations of the Generalized Phase Contrast method as known in the art. LCoS devices of a transmissive configuration may be used directly in a beam path through the integrated optical device. In this way, the number of optical components in the optical system may be minimized, resulting in a particularly simple optical system.

In an embodiment of the inventive device, the input phase mask section comprises an optical path length variation, the optical path length variation being configured so as to give an input phase change corresponding to an output image to be generated. In this way, a particularly simple and potentially economic attractive solution to the input phase mask section may be achieved. This type of device may e.g. be used in laser pointers to generate a shaped light spot (such as an arrow) in an inexpensive yet optically efficient way.

In an embodiment of the inventive device, the input focusing section comprising a lens.

In a particular embodiment of the inventive device, the lens comprises a graded- index lens. In an embodiment of the inventive device, the input focusing section comprises a diffractive zone plate. In this way, a substantially flat input focusing section may be realized, which may result in a more compact device.

In an embodiment of the inventive device, phase contrast filter section comprises an optical path length variation, the optical path length variation being selected to provide a phase shift for electromagnetic radiation at a chosen design frequency. Such an optical path length variation may for instance be realized by forming a "cut-out"-region in the phase contrast filter section adapted to provide the desired phase shift, by selecting the depth of the cut-out along the optical axis. Thus, a particularly simple phase contrast filter (PCF) section may be achieved.

Furthermore, this type of PCF readily lends itself to manufacturing by moulding.

In an embodiment of the inventive device, the device further comprising an output imaging section having a focal length f₂, the output imaging section being arranged in an axial distance substantially equal to f₂ from the phase contrast filter. In this way, optical "infinity" is brought back into the imaging plane of the output imaging section, such that the output intensity image is formed closer to the device, in a distance of 2f₂ from the output imaging section . In an embodiment of the invention, the output imaging section comprises a lens.

In a particular embodiment of the invention, the lens comprises a graded index lens. In an alternative embodiment, the lens of the output imaging section comprises a replaceable standard lens.

In an alternative embodiment, there is no output imaging lens and the far field or infinity image from the phase contrast filter is used instead . Such an embodiment is envisioned to be useful for automotive lights, nudging, or other "outdoor" applications.

In an embodiment of the inventive device, the output focusing section is integrally formed with the phase contrast filter.

In some embodiments, the input phase mask and/or the phase contrast filter are provided as recesses.

In some embodiments, at least a part of an exterior of the integrated optical element is covered by a protective material.

In some embodiments, at least a part of an exterior of the integrated optical element is covered by a protective material comprising a polymer and/or a glass.

In some embodiments, at least a part of an exterior of the input phase mask section and/or the phase contrast filter section is covered by a protective material.

In some embodiments, at least a part of an exterior of the input phase mask section and/or the phase contrast filter section is covered by a protective material comprising a polymer and/or a glass. In some embodiments, an index of refraction of the protective material is between 1.2 and 2.8. Preferably the protective material has an index of refraction that is different from the index of refraction of the material that it is covering. In the figures, a PCF radius has been shown, implying a circular PCF. Generally, it is advantageous to use a PCF adapted to the optical Fourier transform of the beam profile of the light source with which the integrated optical device is used.

Accordingly, in some embodiments, the phase contrast filter is circular.

In some embodiments, the phase contrast filter is asymmetric. In some embodiments, the phase contrast filter is elliptical. The shape of the phase contrast filter would typically be selected to suit the characteristics of the light source with which the integrated optical device is used. Semiconductor lasers often produce a non-circular beam, for instance an elliptical beam. In that case, an elliptical phase contrast filter is well suited. If the input light is circular, a circular phase contrast filter is well suited. If the light source is asymmetric, a corresponding asymmetric phase contrast filter is advantageous.

According to a second aspect, the invention further relates to automotive headlights comprising the integrated optical device according to any one of the above-mentioned embodiments, wherein an output light field of the device is arranged to illuminate a phosphorescent or fluorescent element so as to generate a head light output beam. If a dynamic input phase mask section, such as an LCoS device is used, the headlight may be steerable, e.g. to follow the road.

The inventors envision that the integrated optical device according to the invention is useful for a very broad range of applications from automotive headlights, as mentioned above, to laser pointers with shaped optical output, projectors for entertainment, integration in smart phones, smart light, nudging (e.g. in-store advertisement), and optical encryption. In particular, the device according to the invention is envisioned to be useful for laser image projectors from small hand held, over intermediate size stationary and conference hall size up to full digital cinema versions for 2D and 3D. The device may provide integrated RGB capabilities, or may one colour channel to be compounded with other colour channels. The device may be realized both in a dynamic version allowing active light shaping, and a passive version having a fixed input phase mask section that may be made with low unit costs.

According to a third aspect, the invention further relates to a method of shaping electromagnetic radiation, the method comprising launching an input

electromagnetic field onto an input phase mask section, so as to impose a phase change in parts of the electromagnetic field, the phase change corresponding with the shaping to be generated, and focusing the electromagnetic field with a focusing section having a focal length f. The method further comprising filtering the focused electromagnetic field with a phase contrast filter so as to impose a fixed phase change to the focused electromagnetic field, and coherently mixing the filtered electromagnetic field with an unfiltered reference electromagnetic field part of the input electromagnetic field so as to generate the shaped

electromagnetic field by interference between the filtered electromagnetic field and the reference electromagnetic field. The method is further adapted by either at least the input focusing section and the phase contrast filter section; or at least the input phase mask section and the input focusing section being integrated in an integrated optical element. In this way, shaping of the output electromagnetic field may be achieved efficiently and with a compact device. By providing an input phase mask section with multiple levels of phase change, a corresponding number of multiple output intensity levels may be achieved. Thus, multi-level capabilities are inherent in the inventive device and method.

In an embodiment of the inventive method, the input electromagnetic field comprises laser light.

In an embodiment of the inventive method, the input electromagnetic field comprises light from a super-continuum light source. In an embodiment of the inventive method, the input light field has a substantially Gaussian field distribution.

In another embodiment, the input light field has a substantially tophat field distribution.

This third aspect of the invention is particularly, but not exclusively, advantageous in that the method according to the aspect may be implemented by the integrated optical device according to the first aspect of the invention.

A fourth aspect of the invention provides a radiation device comprising a first and a second integrated optical device in accordance with an embodiment of the first aspect of the invention, wherein

at least one property of the integrated optical element in the first integrated optical device is selected to provide first integrated device operation at a first wavelength,

at least one property of the integrated optical element in the second integrated optical device is selected to provide second integrated device operation at a second wavelength differing from the first wavelength by at least 100 nm.

This typically means that one or more properties, such as focus lengths, radii of curvature, material compositions, recess properties or other applicable

characteristics differ between the first and the second integrated optical device. The difference between the wavelengths may be smaller or larger, such as 50 nm or 200 nm, 300 nm, or 400 nm. The first and/or second wavelength can be outside the visible spectrum.

In some embodiments, the first and second optical devices are arranged with their respective optical axes substantially parallel with one another.

In some embodiments, the radiation device comprises a first, a second and a third optical device in accordance with an embodiments of the first aspect of the invention, wherein the first, second and third integrated optical devices are arranged in parallel, and the first integrated device is configured to be operative as a Red channel, the second integrated optical device is configured to be operative as a Green channel, and the third integrated optical device is configured to operative as a Blue channel. This provides an RGB radiation device that can be used as a radiation source for instance in an RGB projector. The first, second and third integrated optical devices need not be identical to one another.

A fifth aspect provides a 3D printer having a radiation source for curing curable liquid to form a solid 3D object, wherein the radiation source comprises an integrated optical device in accordance with an embodiment of the first aspect of the invention.

The first, second, third, fourth, and fifth aspects of the present invention may each be combined with any of the other aspects. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE FIGURES

The integrated optical device and method of generating an optical image according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible

embodiments falling within the scope of the attached claim set. Figure 1 illustrates an example of a GPC setup realized in bulk optics.

Figure 2 illustrates one embodiment of the integrated optical device according to the invention.

Figure 3 shows two related embodiments of the integrated optical device according to the invention, based on geometric optics.

Figure 4 illustrates two other related embodiments of the device, based on geometric optics and having a replaceable phase mask.

Figure 5 show two related embodiments of the device, based on a graded-index (GRIN) lens.

Figure 6 show two alternative related embodiments of the device, based on a Fresnel lens. Figure 7 show two additional related embodiments of the device, based on an embedded input phase mask section.

Figure 8 schematically illustrates an embodiment of the device based on a diffractive input focusing section.

Figure 9 schematically illustrates an embodiment of an automotive headlight according to the invention.

Figure 10 schematically illustrates an embodiment of another automotive headlight according to the invention.

Figures 11A-11C illustrate protective layers for an integrated optical device according to the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

Figure 1 illustrates a basic setup useful in connection with the generalized phase contrast method. This optical assembly 1 is illustrated as being composed of optical bulk components 3, 5, 7, 9. More specifically, an input light field 2, e.g. from a laser, is launched onto a phase mask 3 resulting in a phase shift to parts of the light field. In this figure, a 0 and % phase shift, respectively, is imposed on the light field, but any values of the phase shift (however remembering the 2% phase ambiguity), and any number of shift levels may be used simultaneously. Thus, for instance, 10 levels may be used between 0 and %, or any other combination. By appropriately selecting the phase shift profile of the input phase mask 3, the intensity profile of an output light signal may be controlled. The phase filtered light field 4 is then allowed to propagate for a distance corresponding to a focal length f of a focusing lens 5, before being focused by the lens 5. In the image plane of the lens 5, a phase contrast filter (PCF) 7 is arranged to apply a phase shift to the focused light field 6, which at this point has been Fourier transformed by the focusing lens 5. The now diverging light field 8 may then be imaged by an imaging lens 9 onto an output plane. Simultaneously to this beam path, a reference field will propagate from a focus point central in the phase mask, via the two lenses 5, 9 in a telescope configuration, and being focused onto the output plane. By interfering the two light fields, an intensity image may be generated in the output 11. Note that if the imaging lens 9 is omitted, an image will still be generated, but in the optical "infinity" - i.e. the far field of the setup. Figure 2 illustrates an embodiment of the integrated optical device 100 according to the invention. Here, optical sections similar in function as those described above in connection with figure 1 are found, but with important differences. Thus, similar reference numerals have been used, and emphasis is made on the differences cf. fig. 1. In this embodiment, the function of the input phase mask and the focusing lens has been integrated in an integrated optical element 120 comprising an input phase mask section and an input focusing section 105 arranged in close connection. The integrated optical element 120 may, e.g., be manufactured as a moulded unit. It is seen that output field should be allowed to propagate for two focal lengths, 2f₂, from an output imaging lens 109, before the desired output is generated. By integrating the phase mask section and the focusing section, alignment of the two sections is fixed upon manufacture, leading to a more robust and stable optical system.

Figures 3a and 3b illustrate two other embodiments of the integrated optical device 100 according to the invention. These embodiments relate to the above- mentioned in connection with figure 2, wherein same or similar reference numerals refer to same or similar parts. Therefore, emphasis is here made to the differences between the embodiments. As shown here, the integrated optical element 120 may be made to also include the PCF 107, i.e. so that the

electromagnetic field propagates within the element throughout phase masking the input, focusing the field, and applying the phase contrast filter shift. In this way, an even further robust and mechanically stable system may be obtained.

Figure 3a illustrates the system wherein the output is imaged with a separate imaging lens 109, analogously to the system described above. Note that as discussed for figure 1, the imaging lens 109 is optional here, provided that the far field output may be used in the particular application. In the embodiment shown, both the input phase mask section 103 and the PCF 107 are provided as recesses, having depths, d_PM, d_PCF that are chosen so as to provide a difference in optical path length corresponding to desired phase shifts, when compared to the un- recessed sections around the input phase mask section and PCF, respectively.

Figure 3b corresponds to the setup shown in figure 2, and illustrates an integrated imaging lens 109, which may be arranged abutting the integrated optical element 120. For applications where operation in the far field is not acceptable, this embodiment provides a particularly convenient device, where aligning is only required for the whole unit, rather than individual elements. The integrated optical element 120 and the integrated imaging lens 109 may be formed of the same or similar material. However, in order to have an optical path length difference in the PCF section to achieve a phase shift, a difference in refractive index is required at least in this section. Alternative embodiments of the PCF section may alleviate this requirement.

An example of properties (dimensions, materials etc.) for use with a green laser is as follows: Glass Example (green laser)

n₀ = 1 Air

n₁ = 1.52 D-K59

λ₀ = 532nm Common green laser

f₁ = 35mm Focal length

2w₀ = 1mm 1/e² Gaussian waist of input beam

d_PM = 511nm (A₀/2)/(_{n i} - 1)

d_PCF = 511nm

Ri = 11.97mm (r^ - 1)/^

ΔΓ = 0.2mm Phase mask radius

Ar_f = 13. lpm PCF radius

An example of properties for use with a red laser: Plastic Example (red laser)

no = 1 Air

λο = 650nm Common red laser

fi = 40mm Focal length

2wo = 1mm 1/e² Gaussian waist of input beam

dpM = 663nm (λο/2)/(ηι - 1)

Ri = 13.15mm fi (m - l)/m

ΔΓ = 0.2mm Phase mask radius

Arf = 18.3 m PCF radius

Figures 4a and 4b illustrate two other embodiments of the integrated optical device 100 according to the invention. These embodiments relate to the abovementioned in connection with figure 2 and 3, wherein same or similar reference numerals refer to same or similar parts. Therefore, emphasis is here made to the differences between the embodiments. In this variation, the integrated optical element 120 comprises the input focusing section 105 and the PCF section 107. An output imaging section 109 may be included, and may be comprised as a conventional lens (fig. 4a), or as an integrated optical output imaging section (fig. 4b). The input phase mask section 103 is a separate component arranged in an axial distance from the input focusing section 105. Depending on the application, a wide selection of phase mask sections are available, e.g a dynamic phase mask, such as an LCoS or phase-only SLM, or a fixed mask, e.g. moulded in a polymer. This arrangement allows for conveniently achieving interchangeable phase masks sections. The phase mask/SLM and first lens do not need to be separated by precisely one focal length. Rather, an output distance (OD) may be adjusted by selecting an input distance (ID).

Figure 5 are drawings which show alternative embodiments, comparable to those shown in figure 3 and 4, wherein like reference numerals refer to same or similar parts. Therefore, emphasis will here be made on the differences between the embodiments. In these embodiments, the focusing section 105 is formed as a graded-index (GRIN) lens, as illustrated by the shading in the figure. In this way, the input and output surfaces of the device may be flat, thereby potentially simplifying the manufacturing process and maintaining a flat optical input phase plane.

Figure 6 are drawings which show other alternative embodiments comparable to those discussed above, where like reference numerals refer to same or similar parts. Therefore, emphasis will here be made on the differences between the embodiments. Particularly, the present embodiments are based on a Fresnel lens, which may be combined with the input phase mask section, as illustrated in figure 6b, to produce an integrated input section 160. This embodiment is particularly close to the one shown in figure 3, based on the geometric lens design, but has the advantage of reducing the thickness of the rounded end. Hence, the phase mask section may be made in a flatter surface.

Figure 7 are drawings which show other alternative embodiments comparable to those discussed above, where like reference numerals refer to same or similar parts. Therefore, emphasis will here be made on the differences between the embodiments. In this case, the input phase mask section 105 is embedded inside the integrated optical element 120. An advantage is that this results in a flat phase mask structure, and is enabled since Fourier optics allows the phase mask section and the input focusing section to be interchanged. Analogously to the situation discussed for figure 4, the distance of the output (OD) would change with the position of the phase mask section, but this may be determined in advance. An example of properties (dimensions, materials etc.) for use with an infrared laser is as follows:

Glass Example (infrared)

no = 1 Air

n₂ = 1.77 S-NPH1

λο = 1070nm IR laser

fi = 25mm Focal length

f₂ = 25mm Output Focal length

2wo = 1mm 1/e² Gaussian waist of input beam

dPM = 1049nm (λο/2)/(ηι - 1)

dpcF = 2058nm (λ₀/2)/(η₂ - m)

R₂ = 10.88mm f₂ (n₂ - l)/n₂

ΔΓ = 0.2mm Phase mask radius

Ar_f = 18.9Mm PCF radius

With a blue laser, an example may look like this:

Plastic Example (blue laser)

no = 1 Air

n₂ = 1.61 Polycarbonate

λο = 450nm Blue laser

fi = 40mm Focal length

f₂ = 50mm Output Focal length

2wo = 1mm 1/e² Gaussian waist of input beam

dPM = 450nm (λο/2)/(ηι - 1)

dpcF = 2046nm (λ₀/2)/(η₂ - m)

R₂ = 18.94mm f₂ (n₂ - l)/n₂

ΔΓ = 0.2mm Phase mask radius

Arf = 12.7Mm PCF radius Figure 8 illustrates an embodiment of the device of the invention based on a diffractive focusing section 105, integrated with the PCF section 107 into the integrated optical element 120. The diffractive focusing section 105 may be realized as a zone plate, corresponding to a converging lens. Zone plates are e.g. attractive in electromagnetic frequency ranges where conventional lenses are not available or practical, such as for x-rays, or for terahertz radiation.

Figure 9 illustrates the working principle of an automotive headlight 200 according to another aspect of the invention. Here, an input light beam 204 is generated by e.g. a pump laser (not shown), before being shaped in the GPC setup 100. This shaped input light 201 is subsequently launched onto a phosphorous element 202 used to generate the actual headlight beam 205. In this way, the desired radiating pattern of the headlight may be controlled by appropriate shaping of the input light, e.g. to avoid blinding on-coming motorists, to limit emission in the vertical direction, etc. If a dynamic variety of the input phase mask section is used, the output light beam may be dynamically shaped to follow the road ahead. Relaying a low sheet-beam could have potential applications as fog headlights. The inventors envision that this embodiment may also be useful for other purposes, e.g. as spotlights or floodlights.

Figure 10 schematically illustrates another embodiment of an automotive headlight 200 according to the invention. Shown here is the integrated optical element 120 assembled with an imaging section 109 for shaping the input pump light 204 to a shaped input beam 201. The integrated optical element 120 as illustrated here comprises the input phase mask section, which may for instance be a cut-out, or a dynamic phase mask device, such as a phase-only SLM. The shaped input beam 201 is shaped to selectively illuminate one or more

phosphorous elements 202, which in turn generate the output headlight beam 205 e.g. by reflection in the one or more reflectors 220. Note that for clarity, the imaging section 109 is simply shown here as a lens. However, each of the phosphorous elements 202 should preferably be arranged in an optical distance substantially equal to two times a focal length of the imaging section 109. One way to achieve this goal is to use a multi-focus device as the imaging section 109, i.e. a device having individual focal lengths suitably chosen for each of the phosphorous elements 202. Alternatively, the shaped input beam 201 may be configured to originate from out of the plane of the figure, such that each of the phosphorous elements 202 may be arranged substantially equidistantly from the integrated optical device 100. Finally, the automotive headlight 200 may be arranged such that the phosphorous elements 202 are in the far field of the integrated optical device 100, such that the imaging section 109 may be omitted.

Figures 11A-11C illustrate embodiments of the integrated optical device 100 according to the invention. These embodiments relate to the above-mentioned in connection with figures 3a and 3b, wherein same or similar reference numerals refer to same or similar parts. Therefore, emphasis is here made to the

differences between the embodiments.

Fig 11A illustrates a device similar to that in Fig. 3a. It further comprises a protective layer 111 that covers the PCF section 107. This prevents that dust and dirt from getting into contact with the PCF.

Fig 11B illustrates a device similar to that in Fig. 11A. It further comprises a protective layer 113 that covers the input phase mask section 103. PCF 107. This prevents that dust and dirt from getting into contact with the PCF.

Fig llC illustrates a device similar to that in Fig. 11B, except there is no protection for the PCF 107.

Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. For instance, the automotive headlights as described here are only one of many applications foreseen by the inventors. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.

Claims

1. Integrated optical device comprising along an optical axis:

an input phase mask section,

an input focusing section having a focal length f_lr

- a phase contrast filter section,

wherein either

at least the input focusing section and the phase contrast filter section or at least the input phase mask section and the input focusing section are integrally formed in an integrated optical element, and the phase contrast filter section is arranged in an axial distance substantially equal to the focal length from the input focusing section.

2. The integrated optical device according to claim 1, wherein the input phase mask, the input focusing section, and the phase contrast filter are integrally formed in the integrated optical element.

3. The integrated optical device according to any one of the preceding claims, wherein the integrated optical element comprises an optical material, the optical material being optically transparent for electromagnetic radiation having a frequency around a chosen design frequency.

4. The integrated optical device according to any one of the preceding claims, wherein the input phase mask section comprises a phase-only spatial light modulator, SLM, device configurable for providing an input phase change corresponding to an output image to be generated.

5. The integrated optical device according to claim 4 wherein the phase-only SLM comprises a liquid crystal on silicon, LCoS, device.

6. The integrated optical device according to any one of the preceding claims, wherein the input phase mask section comprises an optical path length variation, the optical path length variation being configured so as to give an input phase change corresponding to an output image to be generated.

7. The integrated optical device according to any one of the preceding claims, wherein the input focusing section comprising a lens.

8. The integrated optical device according to claim 7, wherein the lens

comprises a graded-index lens.

9. The integrated optical device according to any one of the preceding claims, wherein the input focusing section comprises a diffractive zone plate.

10. The integrated optical device according to any one of the preceding claims, wherein phase contrast filter section comprises an optical path length variation, the optical path length variation being selected to provide a phase shift for electromagnetic radiation at a chosen design frequency.

11. The integrated optical device according to any one of the preceding claims, wherein the device further comprising an output imaging section having a focal length f₂, the output imaging section being arranged in an axial distance substantially equal to f₂ from the phase contrast filter.

12. The integrated optical device according to claim 11, wherein the output focusing section is integrally formed or abuts the phase contrast filter.

13. The integrated optical device according to any one of the preceding claims, wherein the input phase mask and/or the phase contrast filter are provided as recesses.

14. The integrated optical device according to any one of the preceding claims, wherein at least a part of an exterior of the integrated optical element is covered by a protective material, the protective material having an index of refraction different from a material that it is covering.

15. The integrated optical device according to any one of the preceding claims, wherein at least a part of an exterior of the integrated optical element is covered by a protective material comprising a polymer and/or a glass, the protective material having an index of refraction different from a material that it is covering.

16. The integrated optical device according to any one of the preceding claims, wherein at least a part of an exterior of the input phase mask section and/or the phase contrast filter section is covered by a protective material, the protective material having an index of refraction different from a material that it is covering.

17. The integrated optical device according to any one of the preceding claims, wherein at least a part of an exterior of the input phase mask section and/or the phase contrast filter section is covered by a protective material comprising a polymer and/or a glass, the protective material having an index of refraction different from a material that it is covering .

18. The integrated optical device according to any one of the preceding claims, wherein an index of refraction of the protective material is between 1.2 and

2.8.

19. The integrated optical device according to any one of the preceding claims, wherein the phase contrast filter is circular.

20. The integrated optical device according to any one of claims 1-18, wherein the phase contrast filter is asymmetric.

21. The integrated optical device according to any one of claims 1-18, wherein the phase contrast filter is elliptical.

22. Automotive headlights comprising the integrated optical device according to any one of the preceding claims, wherein an output light field of the device is arranged to illuminate a phosphorescent or fluorescent element so as to generate a head light output beam. A radiation device comprising a first and a second integrated optical device in accordance any of the claims 1 to 21, wherein :

- at least one property of the integrated optical element in the first

integrated optical device is selected to provide first integrated device operation at a first wavelength,

- at least one property of the integrated optical element in the second integrated optical device is selected to provide second integrated device operation at a second wavelength differing from the first wavelength by at least 100 nm .

A radiation device in accordance with claim 23, where the first and second optical devices are arranged with their respective optical axes substantially parallel with one another.

A radiation device comprising a first, a second and a third optical device in accordance with one of claims 1-21, wherein the first, second and third integrated optical devices are arranged in parallel, and the first integrated device is configured to be operative as a Red channel, the second integrated optical device is configured to be operative as a Green channel, and the third integrated optical device is configured to operative as a Blue channel.

A 3D printer having a radiation source for curing curable liquid to form a solid 3D object, wherein the radiation source comprises an integrated optical device in accordance with one of claims 1-21.