An apparatus for producing an optically variable film includes a laser configured to emit a beam, a telescoping lens section having a first lens and a second lens spaced apart by a first distance and an interferometer configured to direct the beam toward a workpiece. The laser may be operated at a predetermined power level and the first and second lenses are sized and spaced relative to one another to direct the beam onto the workpiece at about 200-230 dots per inch. The workpiece may include a polyethylene terephthalate (PET) layer configured to be ablated by the beam, forming a microstructure in the surface of the layer. The microstructure may be randomized and used to present non-chroma visual effects.

Provided are a holographic printing device and method using multiple optical heads. The holographic printing device according to an embodiment of the present invention comprises: a fringe pattern generation unit which generates a holographic fringe pattern, and segments the generated fringe pattern into hogels; a multiplexing unit which groups the hogels, segmented by the fringe pattern generation unit, according to area; and a plurality of optical heads which respectively receive the grouped hogels and print the respective hogels in the corresponding areas of a holographic medium. Accordingly, several hogels can be printed on the holographic medium at a time using the multiple optical heads, thus reducing holographic printing time so that even large screen holograms can be printed at high speed.

A system includes a diffractive optical element configured to receive a first beam and a second beam interfering with one another to generate a first interference pattern. The diffractive optical element is also configured to forwardly diffract the first beam and the second beam to output a third beam and a fourth beam. The third beam and the fourth beam interfere with one another to generate a second interference pattern. The system also includes a detector configured to detect the second interference pattern.

A device includes a display configured to generate an image light. The device also includes a waveguide optically coupled with the display and configured to guide the image light to an exit pupil of the device. The waveguide includes a grating including a birefringent material, and a birefringence of the grating is configured to increase along a pupil-expanding direction of the device.

A method of manufacturing a Volume Bragg Grating (VBG) is provided, comprising providing a cylindrical bulk medium made of a transparent glass material and having a central axis along a longitudinal direction, and inscribing an interference pattern in the cylindrical bulk medium. The interference pattern has a plurality of grating fringe elements distributed along a line parallel to the central axis. The method further includes rotating the cylindrical bulk medium about the central axis during said inscribing, thereby azimuthally extending the grating fringes elements. There is further provided a VBG manufactured according to such a method, the use of such a VBG in a CPA system of cladding-pumped fiber laser.

A printing device (106) includes a laser source and a LCOS-SLM (Liquid Crystal on Silicon Spatial Light Modulator). The printing device generates a laser control signal and a LCOS-SLM control signal. The laser source (110) generates a plurality of incident laser beams based on the laser control signal. The LCOS-SLM (112) receives the plurality of incident laser beams, modulates the plurality of incident laser beams based on the LCOS-SL M control signal to generate a plurality of holographic wavefronts (214,216) from the modulated plurality of incident laser beams. Each holographic wavefront forms at least one corresponding focal point. The printing device cures a surface layer or sub-surface layer (406) of a target material (206) at interference points of focal points of the plurality of holographic wavefronts. The cured surface layer of the target material forms a three-dimensional printed content.

An exposure device for recording a hologram. The exposure device includes at least one modulation unit, which is designed to generate a modulation beam representing a reference beam and/or an object beam by impressing a modulation representing at least one holographic element of the hologram onto a laser beam. The exposure device also includes at least one reduction unit, which is designed to generate a modified modulation beam using the modulation beam, the modified modulation beam having a smaller beam diameter than the modulation beam. The exposure device further includes at least one objective lens unit, which is designed to direct the modified modulation beam through an immersion medium onto a recording material in order to record the hologram by exposing the recording material to the modified modulation beam.

A printing device (106) includes a laser source and a LCOS-SLM (Liquid Crystal on Silicon Spatial Light Modulator). The printing device generates a laser control signal and a LCOS-SLM control signal. The laser source (110) generates a plurality of incident laser beams based on the laser control signal. The LCOS-SLM (112) receives the plurality of incident laser beams, modulates the plurality of incident laser beams based on the LCOS-SLM control signal to generate a plurality of holographic wavefronts (214,216) from the modulated plurality of incident laser beams. Each holographic wavefront forms at least one corresponding focal point. The printing device cures a surface layer or sub-surface layer (406) of a target material (206) at interference points of focal points of the plurality of holographic wavefronts. The cured surface layer of the target material forms a three-dimensional printed content.

A copying device for generating a replication hologram that represents a copy of a master hologram. The device includes an object hologram for generating an object wave via a master signal, and a reference hologram for generating a reference wave with the aid of the master signal.

A method and system for forming a holographic structure in a material. The holographic structure is configured to project a selected target image in the far field under illumination of the holographic structure by a laser. The method calculates a modified design for the holographic structure that encodes a unique identifier within the holographic structure for projecting the target image. The method modifies the material by mapping features corresponding to the modified design into the material so as to form the holographic structure. A basic check of the authenticity of the material is performed by checking whether a projected replica of the target image is as expected. A more detailed check of the authenticity of the material is performed by directly inspecting the features in the holographic structure.