WO2016174262A1

WO2016174262A1 - 3d light projection device

Info

Publication number: WO2016174262A1
Application number: PCT/EP2016/059760
Authority: WO
Inventors: Jesper GLÜCKSTAD; Andrew BANAS
Original assignee: Optorobotix Aps
Priority date: 2015-04-30
Filing date: 2016-05-02
Publication date: 2016-11-03

Abstract

The present disclosure to a projection device for receiving and distributing a light beam, comprising: a light shaping element (10) comprising a light shaping profile (11) configured to form a profiled light beam; a lens element (20) configured to transform the profiled light beam into a spatial frequency domain to form a spatial frequency transformed light beam; a spatial frequency filtering element (30) configured to modify the spatial frequency transformed light beam in the spatial frequency domain to form a spatial frequency filtered light beam; and a holographic element (40) configured to diffract the spatial frequency filtered light beam, thereby forming a plurality of projected light beamlets (51) in a spatial volume.

Description

3D light projection device

Field of invention

The present invention relates to a projection device, in particular for providing a 3D light distribution. Further, the present invention also relates to a projection system and a method for receiving and distributing a light beam.

Background of invention

Shaping light based on phase-only techniques is important in many commercial, industrial or research applications due to its efficient energy utilization. Phase-only light shaping approaches can save more than 90% of the energy that is lost if using simple blocks or absorbing filters.

Generalized Phase Contrast (GPC) is a phase-to-intensity light shaping technique that can generate contiguous speckle-free extended shapes of spatially coherent light. As GPC is a point-to-point mapping of an input phase mask into output intensity, the input phase mask sets constraints on the distribution of the output beams, limiting the output to a single copy of the intensity pattern to the output imaging plane in two dimensions.

Holography is advantageous for generating sparse diffraction-limited spots with controllable axial and lateral locations. However, holography, generally suffers from noisy or speckled output when creating extended shapes of light.

Thus, there is a need for a device that is able to provide an output that is not limited to a single copy of the intensity pattern, not limited to two dimensions in a plane and at the same time can be speckle-free and/or noise-free. Summary of invention

The present disclosure combines in general the strengths of a phase-to-intensity light shaping technique and holography and relates to a device that is capable of distributing a plurality of well-defined speckle-free extended optical shapes over a wide working volume.

Potential uses of this new light shaping approach include optical trapping and manipulation, cell sorting and characterization, phase security and encryption, advanced microscopy, structured illumination in 2D and 3D, optical lattices, advanced spatial spectroscopy, laser display units, laser materials processing and stimulation for biological research such as in neurophotonics and one- and two-photon optogenetics. Specifically, the present disclosure relates in a first aspect to a projection device for receiving and distributing a light beam, comprising: a light shaping element comprising a light shaping profile configured to form a profiled light beam; a lens element configured to transform the profiled light beam into a spatial frequency domain to form a frequency transformed light beam; a frequency filtering element configured to modify the frequency transformed light beam in the frequency domain to form a frequency filtered light beam; and a holographic element configured to diffract the frequency filtered light beam, thereby forming a plurality of projected light beamlets. In one embodiment, the holographic element is located in a plane substantially identical to the plane of the spatial frequency filtering element.

In a second aspect of the present disclosure is provided a method for receiving and distributing a light beam, comprising: forming a profiled light beam using a light shaping element comprising a light shaping profile; forming a spatial frequency transformed light beam from the profiled light beam into a spatial frequency domain using a lens element; forming a frequency filtered light beam in the frequency domain from the frequency transformed light beam using a frequency filter; and forming a plurality of projected light beamlets from the frequency filtered light beam using a hologram configured to diffract the light beam. In a third aspect of the present invention is provided a projection system for diffracting light from a light source, comprising a single light source or multiple light sources, wherein the light source is adapted to emit a light beam into the projection device as described above. If multiple light sources are used the light sources may optionally be adapted to spatially isolate their respective spatial frequency distributions.

In using a device and/or method and/or system as described above, there is provided a new way of distribution of a light beam. One effect of the present disclosure is that it facilitates a compact and low cost device. First of all, a compact device may be obtained because the light shaping element is in front of the remaining elements in the device. Secondly, a low cost device may be obtained because none or just one of the elements may be a configurable or programmable element. In conventional projection devices there are typically two or more configurable or programmable elements.

Examples of configurable or programmable elements may be a spatial light modulator (SLM). Thus, the present disclosure provides a device where it is possible to use only a single or no SLM in order to project a plurality of light beamlets. A further advantage of the present disclosure is that it also possible to provides a speckle-free distribution of a light beam.

In a fourth aspect of the present disclosure is provided a microscope system, comprising a projection system as described above, and a microscope configured to receive the spatial light distribution.

The outlined effects and advantages among others will be described in further details in this disclosure. Applications of the present invention may relate to the following:

Planar Light Valve (PLV) based spatial light modulation for a variety of applications including high power handling, ultrafast switching, 'digital-to-plate', projection in UV, infrared and the visible

Computer-to-plate (CtP) and direct transfer of digital content onto e.g. aluminum plates used in offset printing

Exposing of large-scale flexible aluminum substrates to spatially modulated high-intensity near-infrared laser light in order to thermally modify surfaces

High-performance display applications such as digital cinema, large-venue projection, planetariums, simulators and virtual reality displays - Direct light-write lithography with so-called laser-based direct-write mask-less solutions to avoid the time, expense and effort of generating and maintaining traditional photo-mask technology

Rapid processing of large wafers with micron- or even nano-size features on high-resolution spatial resolution grids Combined spectral and spatial light shaping modalities

Raster-less and fully parallel industrial marking and materials processing with high-intensity lasers used to melt, etch, sinter, ablate, or in other way modify light-exposed materials relative to their surroundings

Direct laser writing and processing of hundreds or even thousands of spatially encoded beamlets all writing to material processed surfaces in parallel and in 2D and/or 3D

Super-resolution microscopy such as STED, PALM and STORM but not limited hereto

Augmented and virtual reality applications in 2D and/or 3D

Speckle-free or speckle-reduced color or monochrome holographic applications

Contemporary optical telecom applications using the spatial dimension in addition to or instead of the temporal

Space Division Multiplexing (SDM) applications

Spatial addressing of new higher-order mode fibers, multi-core fibers and contemporary photonic crystal fibers

Addressing photonic crystals in 2D and/or 3D

Writing photonic crystals in 2D and/or 3D

Mode matching in 2D and/or 3D in fibers, waveguides or free space

applications

Mode selection applications for intra- or extra cavity laser radiation

Tailored applications to liquid crystal on silicon (LCoS) spatial light modulators; Tailored applications to MOEMS spatial light modulators

Tailored applications to 2D and/or 3D imaging endoscopes including fiber- based endoscopes

Tailored applications to super-contiuum light sources (white light lasers) - Tailored applications to Optical Tomography applications including OCT; - Tailored applications for parallel laser scanning in 2D and/or 3D

3D Television

Spatial laser-based sign-posts and/or road signs

Projected static or dynamic guiding lights in 2D and/or 3D for supermarket floors, walls and/or screens

Medical projections in 2D and/or 3D

Pre-surgery applications in 2D and/or 3D Atom optics applications in 2D and/or 3D - Quantum optics applications in 2D and/or 3D

Phase tomography applications in 2D and/or 3D Optical particle sorting applications in 2D and/or 3D

Optical cell sorting applications in 2D and/or 3D Optical catapulting applications in 2D and/or 3D - Optical space and aeronautics applications Optical satellite communication applications Optical micro-robotics applications - Optical insect scanning, counting and analyzing applications

Optical type-writer Applications for car light

Applications for motorbikes, small motorbikes and bicycles

Laser show applications - Biomedical applications such as two photon optogenetics, neurophotonics and/or SLM Illumination

Illumination such as for car light, cinema, street light, entertainment - Materials processing such as cutting, welding, marking (tracking & identification of mechanical parts, medical devices, food & drug) and/or micromachining and drilling (stents, cellphones, tablets, tv, solar panels)

Lithography, as the present invention may be ideal for repeating a pattern Description of drawings

Fig. 1 shows a first example of a device according to the present disclosure. Fig. 2 shows a second example of a device according to the present disclosure.

Fig. 3 shows a third example of a device according to the present disclosure. Fig. 4 shows a fourth example of a device according to the present disclosure. Fig. 5 shows a fifth example of a device according to the present disclosure. Fig. 6 shows an effect of using a spatial frequency filtering element according to the present invention.

Detailed description of the invention

The presently disclosed device comprises at least four elements - the light shaping element, the lens element, the spatial frequency filtering element, and the holographic element. According to the disclosure, the order of the elements is preferably ordered sequentially as listed. As will be described below, it may in some embodiments be possible to re-order or combine some of the elements. The elements can be spatially re-arranged with mirrors to limit the consumed footprint or adapt with the applications' constraints. The elements are described below in further detail.

Lens elements In addition to the at least four elements, additional lens elements may be provided.

The projection device as herein described may in some embodiments further comprise additional lens elements adapted to focus the plurality of light beamlets to form a plurality of focused light beamlets in one or more output focal planes. A lens element is able to convert light from the spatial domain and into the frequency domain, or the other way around. Using Fourier optical calculations to see the change of variables, one representation of the frequency domain may be the Fourier frequency domain, or simply the Fourier domain. In view of a typical holographic display, there is commonly used a lens after a holographic element to display an intensity profile, but such setups provide holograms that are speckled. The present disclosure may provide a speckle- free hologram by having the light shaping element, frequency transforming means, and the frequency filtering element before the holographic element. Thus, the present disclosure may with the additional lens elements, be regarded as a conventional holographic setup, but with two lens elements set up before the holographic setup. The light shaping element

The light shaping element together with the lens element, i.e. the first elements in the device, may be responsible for defining the point spread function (PSF) of the output beamlets. The light shaping element together with the frequency transforming element may provide a desired illumination for the remaining elements, i.e. for the frequency filtering element and the holographic element. As such, the light shaping element may be intended for being used for forming an input that is related to illumination of a holographic element. In this regard, the light shaping element may be considered as a mask, for example a phase mask as preferred, or an amplitude mask.

In the embodiment where focusing of the light beamlets is provided with the additional lens elements, the light shaping profile may be selected such that the light beamlets have output shapes formed as top-hat profiles. In this case, these profiles do not overlapp with out-of-phase point spread functions (PSFs), i.e. PSFs formed by the light shaping element, that result in speckles or noise. Using optical calculations, for example Fourier optics, it may be possible to calculate which profile that provides light beamlets that have contiguous phase and amplitude. An example of contiguous light beams, i.e. when sufficiently distributed by the holographic element, may for example be so-called top-hat beam profiles. Thus, the light shaping profile may be selected such that the focused beamlets are converting a given beam profile to for example a top-hat beam profile. An effect of having the beamlets formed by focused light beams that do not overlap, is that the projected light beams, i.e. the hologram, as displayed by the holographic element, wherein the illumination for the holographic element is provided by the light shaping element, do not interfere with each other, and thereby do not produce speckles. The present disclosure may thus provide a speckle-free hologram by selecting or optimizing the light shaping profile.

Preferably, the light shaping unit may be a phase-only element. In this way there may be no loss of intensity, and the output signal, i.e. the projected light beamlets may be optimally intense.

In another preferred embodiment of the present disclosure, the phase-only element is a non-configurable phase-only element, such as a phase mask, for example made on a piece of glass material. Hereby, a low cost system is obtained.

However, in another embodiment of the present disclosure, the phase-only element is a programmable phase-only element, such as a spatial light modulator (SLM). This allows using a computer to change the shape of the beamlets. In some embodiments of the present disclosure, the light shaping profile comprises an inner part that is configured for allowing a central part of the light beam to pass unhindered, and an outer part that is configured for altering a peripheral part of the light beam.

In a preferred embodiment of the present disclosure, the outer part is altering the phase of the light beam by introducing a phase shift relative to the inner part.

In a more preferred embodiment of the present disclosure, the phase shift is ττ. It can be found using Fourier optics, that such a phase shift provides means for transferring a Gaussian beam profile to a top-hat beam profile.

In an alternative embodiment of the present disclosure, the outer part is altering the amplitude of the light beam by blocking the light. In this way the light shaping element may be an amplitude mask, i.e. reducing the amount of transferred light. In this sense, the light shaping element is known as an apodization mask. When not related to amplitude apodization, it may be stated that the light shaping element is a phase apodization mask. Regardless of which configuration to be used, the light shaping element is for illumination, meaning illumination of the holographic element and defining the shape of the output beamlets. In other words, the beamlet distribution or image may be provided by the holographic element, and the beamlet shape may be provided by the light shaping element. The present disclosure thus provides an efficient way of displaying a light distribution.

The spatial frequency filtering element

The spatial frequency filtering element may in general be a phase contrast filter that is configured for maximizing contrast in the distributed light. There exist various phase contrast filters such as Zernike filters and the like. However, in a preferred embodiment of the present disclosure, the spatial frequency filtering element is a phase contrast filter (PCF), where through phase shifting the lower spatial frequencies is done. A difference between a Zernike filter and a PCF is that the PCF is not based on the Zernike approximation, where a phase shift less than 1 radian is applied, and the PCF provides therefore an improved contrast over a Zernike filter. The PCF is for example described in detail in WO 2005/0961 15 which is hereby incorporated by reference in its entirety. One difference between the setup described in WO 2005/0961 15 and the present disclosure is that the present disclosure provides a holographic element optically superposed with the frequency filtering device, the frequency filtering device is referred to a Fourier filter in WO 2005/0961 15, whereby the present disclosure is able to provide a device and system that is more compact than that disclosed in WO

2005/0961 15, in particular because the holographic element in the present invention is configured to define a distribution of the frequency filtered light beam, meaning that the holographic element is configured to be placed where there is frequency filtered light beam, and not in absence of a frequency filtered light beam as is required in the disclosure of WO 2005/0961 15. Therefore, the present disclosure provides means for providing a 3D hologram using a compact and/or low-resolution holographic element, thereby providing a low cost and efficient solution to 3D hologram display. The present disclosure also provides means for using only one configurable element, such as an SLM, whereas the disclosure of WO 2005/0961 15 requires two SLMs coupled to each other via a computer. Having two SLMs coupled to each other as disclosed in WO 2005/0961 15 provides close to speckle-free light distribution, but the setup is much more demanding that the present disclosure. However, the present disclosure may provide full speckle-free light distribution and much more efficient than that described in WO 2005/0961 15. Thus, the present disclosure provides an alternative method and/or system to obtain a speckle-free light beamlet distribution.

In the configuration with a PCF, the presently disclosed device and method may resemble a Generalized Phase Contrast (GPC) setup, in particular a GPC setup, where the light shaping element is setup to form a shaped output from a Gaussian input, except that in the present disclosure, the device further comprises a holographic element together with the phase contrast filter. An effect of having the holographic element together with the PCF, rather than having the holographic element as the first element, similar to a GPC setup, is that the configuration according to the present disclosure provides a device that is able to also provide an intensity profile based on the light shaping element and distributed in 3D. A GPC setup is able to only provide an intensity profile to be sharply imaged in a 2D plane. The present disclosure is therefore not limited to a single central beamlet and not limited to the usual imaging plane, but is stil capable of doing so if desired. Thus, the present disclosure provides means for obtaining a compact device that is able to provide 3D speckle-free intensity projections. In another preferred embodiment of the present disclosure, the spatial frequency filtering element is a non-configurable phase-only element. An example of a non- configurable phase-only element is the PCF. An effect of using a frequency filtering element, in particular a PCF, is that contrast at the output, for example at the focal planes, may be better than a device where a frequency filtering element is not used. An example of the improvement in contrast, as by comparison to not using a PCF and using a PCF, can be seen in Fig. 6.

In some embodiments of the present disclosure, the outer part may be altering the phase of the light beam by introducing a phase shift relative to the inner part.

In other embodiments of the present disclosure, the spatial frequency filtering element is a programmable phase-only element, such as a spatial light modulator (SLM). The same SLM may have the holographic element encoded on it.

Most preferably, the spatial frequency filtering element may comprise an inner part that is configured for allowing a central part of the light beam to pass unhindered, and an outer part that is configured for altering a peripheral part of the light beam.

The holographic element

The holographic element is configured for providing a hologram, i.e. it is a medium where information is present, and displays a hologram when illuminated. Sometimes, the holographic element is referred to as a hologram. Examples of holograms are thin and thick (volume) holograms. A simple hologram may be a grating that provides distribution of a light beam into a plurality of light beams. A displayed hologram may be a computer generated hologram.

As described above, the holographic element may be a non-configurable phase-only element, such as a thin and thick (volume) hologram.

However, and in relation to a computer generated hologram, or digital holography, the holographic element may be a programmable phase-only element, such as a spatial light modulator (SLM). Using an SLM has several advantages. For example, for compactness, the same SLM may have the spatial frequency filtering element encoded on it.

In general the holographic element may allow for multiple copies of the intensity imaged light shaping element at the output. Using an SLM the distribution of the copies, along the output plane or along the axial direction, may be controlled through the holographic element. The overall intensity/energy may be distributed among the shape copies making them dimmer with more copies. The relative brightness of each shape copy need not be equal, and may be tweaked using the SLM or pre-configured in the holographic element.

The holograms as provided by the SLM may numerically be calculated using algorithms such as the Gerchberg-Saxton (GS) algorithm, which is commonly used in digital holography. The illumination patterns resulting from the Fourier transformed illuminated light shaping element may be used as input constraints in the algorithm. The output constraints applied to the algorithm may determine the

distribution/arrangement of the output.

In one embodiment, the holographic element is located in a plane substantially identical to the plane of the frequency filtering element. Such a configuration provides for a compact device. In a configuration where the frequency transforming means is free- space, the hologram may optimally be placed at the far-field of the illuminated light shaping element.

In a preferred embodiment of the present disclosure, the holographic element and the spatial frequency filtering element are integrated into one element. For example, both frequency filtering element and hologram may be on the same SLM. Such a

configuration provides for a compact device.

In an alternative embodiment of the present disclosure, the holographic element is located in a Fourier plane of the projection device.

The projection system

According to the present disclosure, the projection system may further comprise any of the features as described above. In one embodiment of the present disclosure, the light beam comprises a beam profile that is a Gaussian function. This may for example be the case, when the light source is a laser. In some embodiments of the present disclosure, the light source is a multi-color laser, such as a super continuum laser or composite RGB laser.

In another embodiment of the present disclosure, the light source is a laser comprising a laser fiber, such that the light beam is emitted from the laser fiber.

In yet another embodiment of the present disclosure, the light shaping element is integrated on the light source. For example, the light shaping element may be integrated on a tip of the laser fiber. Having such a configuration may allow for a very compact system. Because the light shaping element may be integrated on the light source, the surface may be relatively small, and thus be an efficient way of producing a system as disclosed herein.

As the Fourier transformed input of the light shaping element mask is used as illumination, it is desirable to have it broad enough to cover the area of the holographic element. One way of achieving this is to have a small input laser profile and input from the light shaping element. This may for example be realized by having the light shaping element integrated on the light source, as for example, having the light shaping element integrated on a tip of the laser fiber. The light shaping element may be etched or additively manufactured on a tip of a single mode fiber (normally a few microns).

It is also possible to have the input light converging into a small light shaping element, then have it diverged and collimated before illuminating the holographic element.

In a more preferred embodiment of the present disclosure, the frequency filtered light beam comprises a beam profile that is a Fourier transform of a desired shape such as an Airy-like or sinc-like function for a circular or rectangular beam, respectively. Such a beam profile may provide a speckle-free distribution of beamlets that are copies of the desired shape. Microscope system

According to the fourth aspect of the present disclosure, and in one embodiment of the present disclosure, the microscope system is configured for sorting objects. In particular, the microscope system may be configured for sorting objects and using the spatial light distribution for sorting the objects. Because of the ability to provide a 3D light distribution, this has several advantages, for example when objects are not in a single plane. For example, the objects may be cells, for example in a flow cytometer, implementing a microscope. Various applications other than a microscope are possible. Examples of applications may be related to display of hologram in relation to for example entertainment, such as TV and/or computer games.

Method According to the method as disclosed herein, the method may be performed by a projection device as described herein.

Example 1 - an embodiment of the present disclosure:

Fig. 1 shows an example of the present disclosure and shows a projection device for receiving and distributing a light beam 00, comprising: a light shaping element 10 comprising a light shaping profile 11 configured to form a profiled light beam 12; a lens element 20 configured to transform the profiled light beam 12 into a spatial frequency domain to form a spatial frequency transformed light beam 21 ; a spatial frequency filtering element 30 configured to modify the spatial frequency transformed light beam 21 in the spatial frequency domain to form a spatial frequency filtered light beam; and a holographic element 40 configured to diffract the spatial frequency filtered light beam, thereby forming a plurality of projected light beamlets 41 (not shown). The device further comprises an additional lens element 50 adapted to focus the plurality of light beams to form a plurality of focused light beams in more output focal planes 51. In this example the light shaping element 10 is a phase-only element, in particular a non- configurable phase-only element. As can further be seen, the light shaping profile 11 comprises an inner part 13 that is configured for allowing a central part of the light beam 00 to pass unhindered, and an outer part 14 that is configured for altering a peripheral part of the light beam 00. The outer part is altering the phase of the light beam by introducing a phase shift relative to the inner part, in particular the phase shift is TT, thereby producing a spatial frequency filtered light beam comprising a beam profile that is a sinc-function, such that a Gaussian light beam 00 is converted to a plurality of top-hat light beamlets 51 after being distributed by the holographic element 40. Because of this, the output of the light distribution is speckle-free. The spatial frequency filtering element 30 is a non-configurable phase-only element. The lens elements (20 and 50) are here shown as two elements, i.e. two lenses, each having a focal length f.

Example 2 - another embodiment of the present disclosure:

Fig. 2 shows another example of the present disclosure and shows a projection device for receiving and distributing a light beam 00, comprising: a light shaping element 10 comprising a light shaping profile 11 configured to form a profiled light beam 12; a lens element 20 configured to transform the profiled light beam 12 into a spatial frequency domain to form a spatial frequency transformed light beam 21 ; a spatial frequency filtering element 30 configured to modify the spatial frequency transformed light beam 21 in the spatial frequency domain to form a spatial frequency filtered light beam; and a holographic element 40 configured to diffract the spatial frequency filtered light beam, thereby forming a plurality of projected light beamlets 41 (not shown). The device further comprises an additional lens element 50 configured to adapted to focus the plurality of light beamlets to form a plurality of focused light beamlets in more output focal planes 51. In this example the light shaping element 10 is a phase-only element, in particular a non-configurable phase-only element. As can further be seen, the light shaping profile 11 comprises an inner part 13 that is configured for allowing a central part of the light beam 00 to pass unhindered, and an outer part 14 that is configured for altering a peripheral part of the light beam 00. The outer part is altering the phase of the light beam by introducing a phase shift relative to the inner part, in particular the phase shift is ττ, thereby producing a spatial frequency filtered light beam comprising a beam profile that is a sinc-function, such that a Gaussian light beam 00 is converted to a plurality of top-hat light beamlets 51 after being distributed by the holographic element 40. Because of this, the output of the light distribution is speckle-free. The spatial frequency filtering element 30 is a non-configurable phase-only element. The lens element 20 is here an element with no focusing power and no refractive index change, i.e. identical to free space, propagating in a distance d, whilst the additional lens element 50 is a lens having a focal length f. Example 3 - a third embodiment of the present disclosure:

Fig. 3 shows a device similar to that described and shown in Fig. 1 , except that in this example there are two additional lens elements, here shown as two lenses, in-between the spatial frequency filtering element 30 and the holographic element 40, thereby providing a system, where the spatial frequency filtering element 30 and the

holographic element 40 are in conjugate planes. In this embodiment, the holographic element is in a Fourier plane of the projection device. The spatial frequency filtering element is also located in a Fourier plane of the projection device.

Example 4 - a fourth embodiment of the present disclosure related to a reflective system:

Fig. 4 shows a device that in principle is similar to that described and shown in Fig. 1. The only difference is that the spatial frequency filtering element 30 is here a reflective element, rather than a transmitting element as shown in Figures 1 -3. This example shows a very compact design. Example 5 - a fifth embodiment of the present disclosure using a reflective light shaping element:

Fig. 6 shows an example wherein a reflective optical element is used as the light shaping element 10. Such element may be an SLM allowing the output beamlet shapes to be programmed. It may also be a mirror with a raised or depressed region defining the shape of the output beamlets.

Example 6 - an example of an effect of the spatial frequency filtering element:

Fig. 6 shows an example of an effect of using the spatial frequency filtering element according to the present disclosure. In Fig. 6.A, there is shown a phase input as provided by the holographic element. In Fig. 6.B, there is shown the amplitude output without a spatial frequency filtering element. In Fig. 6.C, there is shown the amplitude output with a spatial frequency filtering element, in this example, a PCF. Comparing 6.B with 6.C, it can be seen that an improved contrast in amplitude is achieved in using the spatial frequency filtering element. Example 7 - An application of the present invention - 3D printing:

Additive manufacturing or 3D printing wherein an efficiently formed well-defined unit shape such as a top hat is used for scanning instead of a tiny spot. The light distribution as formed by the present invention covers a greater area per given time, has sharper boundaries and is more robust to depth variations, hence leading allowing 3D printing with higher speed and quality. Higher speeds and quality makes 3D printing more practical and brings it closer to serious large-scale production instead of just prototyping. High speeds are also relevant for medical applications where implants or splices need to be deployed to the patient as quickly as possible. With sufficient laser power and a dynamic SLM, multiple top hats can be scanned across the photopolymer and therefore complete a 3D printed layer in much less time. Example 8 - Another application of the present invention - Supercontinuum and multicolor lasers:

Efficiently shaped multispectral beams have many applications in research. Different wavelengths, efficiently shaped into uniformly intense tophats, for example, can be used to excite specimens in neurophotonics or optogenetics. 3D spatial selectivity can be added to multi-spectral applications such as spectroscopy, fluorescence microscopy or optical coherence tomography, while the efficiency means that less power is required from the state-of-the-art supercontinuum laser. Composite lasers containing RGB can be efficiently shaped for display or entertainment applications. Example 9 - A third application of the present invention - Materials processing:

Highly parallelized laser engraving with well-defined shapes, not limited to circles. For example, laser marked QR codes can be made quickly and with sharply defined straight edges by scanning a square shaped beam in the processed material. Using cheaper static phase hologram masks instead of a dynamic, predefined periodic array of the shape can be used for creating periodic structures such as photonic crystals, gratings, or other semiconductor devices. Specialized laser shapes have also increased performance or processing quality for laser cutting, welding, drilling or trepanning. Specialized beam shapes can have specific functions on the processed material. The present invention offers the possibility to parallelize these processes and generate the special beam shapes with higher qualities in comparison to diffractive or holography-only means.

Example 10 - A fourth application of the present invention - Optical manipulation and cell sorting:

The present invention allows the formation of more evenly distributed beamlet intensities or beamlets with specialized shapes. Such beamlets can be optimized to be more effective at sorting cells while minimizing radiation induced thermal or chemical effects. For example a beamlet can be doughnut shaped to minimize radiation at the center of the cell while maximizing scattering forces at the periphery. In optical manipulation, the shape of the beamlets can be adapted to match the shape of the structured objects and hence maximize the trapping performance.

Example 11 - A fifth application of the present invention - Structured microscopy:

State of the art microscopy such as STED, STORM, PALM, rely on structured laser beams. The present invention can efficiently provide the required structured beams into 3D biological media, while being free from speckles.

Example 12 - A sixth application of the present invention - Intelligent lighting:

Static phase elements made from plastic or glass can be produced economically and used for more common applications such as structured illumination for guiding, displays and sign applications or to aid in machine vision such as that found in motion detection for video game control or 3D profile measurements.

Claims

A projection device for receiving and distributing a light beam, comprising:

- a light shaping element comprising a light shaping profile configured to form a profiled light beam;

- a lens element configured to transform the profiled light beam into a spatial frequency domain to form a spatial frequency transformed light beam;

- a spatial frequency filtering element configured to modify the spatial frequency transformed light beam in the spatial frequency domain to form a spatial frequency filtered light beam; and

- a holographic element configured to diffract the spatial frequency filtered light beam, thereby forming a plurality of projected light beamlets in a spatial volume,

wherein the holographic element is located in a plane substantially identical to the plane of the spatial frequency filtering element.

The projection device according to claim 1 , further comprising an additional lens element adapted to focus the plurality of light beamlets to form a plurality of focused light beamlets in one or more output focal planes.

The projection device according to claim 2, wherein the light shaping profile is selected such that the focused light beamlets have output shapes formed as top-hat profiles.

The projection device according to any of the preceding claims, wherein the light shaping unit is a phase-only element.

The projection device according to claim 4, wherein the phase-only element is a non-configurable phase-only element.

6. The projection device according to claim 4, wherein the phase-only element is a programmable phase-only element, such as a spatial light modulator.

The projection device according to any of the preceding claims, wherein the light shaping profile comprises an inner part that is configured for allowing a central part of the light beam to pass unhindered, and an outer part that is configured for altering a peripheral part of the light beam.

8. The projection device according to claim 7, wherein the outer part is altering the phase of the light beam by introducing a phase shift relative to the inner part.

9. The projection device according to claim 8, wherein the phase shift is ττ.

10. The projection device according to claim 7, wherein the outer part is altering the amplitude of the light beam by blocking the light.

1 1 . The projection device according to any of the preceding claims, wherein the spatial frequency filtering element is a phase contrast filter. 12. The projection device according to any of the preceding claims, wherein the spatial frequency filtering element is a non-configurable phase-only element.

13. The projection device according to any of the preceding claims, wherein the spatial frequency filtering element is a programmable phase-only element, such as a spatial light modulator.

14. The projection device according to any of the preceding claims, wherein the spatial frequency filtering element comprises an inner part that is configured for allowing a central part of the light beam to pass unhindered, and an outer part that is configured for altering a peripheral part of the light beam.

15. The projection device according to claim 14, wherein the outer part is altering the phase of the light beam by introducing a phase shift relative to the inner part.

16. The projection device according to any of the preceding claims, wherein the holographic element is a non-configurable phase-only element.

17. The projection device according to any of the preceding claims, wherein the holographic element is a programmable phase-only element, such as a spatial light modulator.

18. The projection device according to claim 16, wherein the holographic element and the spatial frequency filtering element are integrated into one element.

19. The projection device according to any of the preceding items, wherein the holographic element is located in a Fourier plane of the projection device.

20. A projection system for diffracting light from a light source, comprising a light source, wherein the light source is adapted to emit a light beam into the projection device according to claim 1 .

21 . The projection system according to claim 20, further comprising any of the features 2-19.

22. The projection system according to any of the claims 20-21 , wherein the light beam comprises a beam profile that is a Gaussian function.

23. The projection system according to any of the claims 20-22, wherein the light source is a multi-color laser, such as a super continuum laser or composite RGB laser.

24. The projection system according to any of the claims 20-23, wherein the light source is a laser comprising a laser fiber, such that the light beam is emitted from the laser fiber.

25. The projection system according to any of the claims 20-24, wherein the light shaping element is integrated on the light source.

26. The projection system according to any of the claims 23-25, wherein the light shaping element is integrated on a tip of the laser fiber.

27. The projection system according to any of the claims 20-26, wherein the

frequency filtered light beam comprises a beam profile that is an Airy-like or sinc-function.

28. A microscope system, comprising a projection system according to any of the claims 20-27, and a microscope configured to receive the spatial light distribution.

29. The microscope system according to claim 28, wherein the microscope system is configured for sorting objects.

30. The microscope system according to any of the claims 28-29, wherein the

microscope system is configured for sorting objects and using the spatial light distribution for sorting the objects.

31 . The microscope system according to any of the claims 29-30, wherein the

objects are cells.

32. A method for receiving and distributing a light beam, comprising:

- forming profiled light beam using a light shaping element comprising a light shaping profile;

- forming a spatial frequency transformed light beam from the amplitude profiled light beam into a spatial frequency domain using a lens element;

- forming a spatial frequency filtered light beam in the spatial frequency domain from the spatial frequency transformed light beam using a spatial frequency filtering element; and

- forming a plurality of projected light beams from the spatial frequency filtered light beam using a holographic element configured to diffract the light beam.

33. The method according to claim 32, wherein the method is performed by a

projection device according to any of the claims 1 -27.