Patent Application
20140022617
The present invention relates generally to a holographic imaging and, more particularly, to a holographic imaging apparatus and method for creating freeform holographic images.
Holograms have long been used for security to indicate that a document or product is authentic and to increase the attractiveness of goods such as lottery and entertainment/sporting event tickets, product packaging such as for DVDs, event programs, calendars and magazines. Indeed, methods and apparatuses for creating holographic optical elements on a recording medium, i.e., substrate, to create an overall optical illusion have been known in the art for some time. As is well known, many such existing apparatuses may include an imaging table, such as a platen, on which the substrate is placed, an imaging laser and associated optics. One of the most well known types of holographic imaging apparatus is a split beam holographic imaging apparatus, which splits a laser into two beams, an object beam and reference beam. The object beam is spread, reflected off of an object and directed onto the recording medium. The reference beam travels directly onto the recording medium. When the two laser beams reach the recording medium, their light waves intersect to create an interference pattern on the substrate, thereby producing a holographic image having certain optical effects.
Notably, however, with known systems, the desired holographic image or optical elements are typically imaged as a whole, in an analog fashion, by using a master that creates the holographic design or optical element on the substrate. For example, as shown in
As best shown in
As will be readily appreciated, such step and repeat process, in addition to being more labor intensive and less customizable, leaves a visible line of demarcation between one image and the next. While there are some techniques that may be carried out to lessen the visibility of such lines, all such step and repeat processes invariably leave some form of demarcation or recombine lines in the final pattern.
Accordingly, while known holographic imaging apparatuses utilizing physical imprinting or surface relief are effective to a certain degree, such apparatuses are limited in the shape and intricacy of holographic images and optical elements that can be produced.
It has been discovered, however, that by imaging in a digital fashion, i.e., pixel by pixel, certain advantages such as the ability to create holographic images and optical elements of any shape and size may be realized.
It is an object of the present invention to provide a holographic imaging apparatus.
It is another object of the present invention to provide a freeform holographic imaging apparatus that is capable of creating holographic images/optical elements on a thin substrate.
It is another object of the present invention to provide a freeform holographic imaging apparatus capable of creating holographic images and optical elements having complex shapes and designs.
It is another object of the present invention to provide a freeform holographic imaging apparatus that is capable of creating holographic images and optical elements of various shapes and sizes.
It is another object of the present invention to provide a freeform holographic imaging apparatus that obviates the need to utilize mechanical recombination to produce an integrated holographic image comprising various optical elements.
It is another object of the present invention to provide a freeform holographic imaging apparatus that is capable of creating holographic images and optical elements on a pixel-by-pixel basis.
It is another object of the present invention to provide a freeform holographic imaging apparatus capable of creating holographic images having various optical effects utilizing the diffraction of light.
It is another object of the present invention to provide a freeform holographic imaging apparatus that is capable of creating optical elements that mimic common optical effects, such as the optical effect of a lens.
An embodiment of the inventive freeform holographic imaging apparatus includes an imaging table for supporting a substrate, an imaging beam positioned adjacent to the imaging table; and a controller operatively connected to the imaging beam and configured to control a position of the imaging beam with respect to the imaging table. The controller is configured to control the imaging beam to image first and second holographic optical elements on the substrate, wherein each of the first and second holographic optical elements are a single pixel. The first holographic optical element is imaged according to a first parameter set and the second holographic optical element is imaged according to a second parameter set.
These and other objects, features and advantages of the present invention will become apparent in light of the detailed description of the best mode embodiment thereof, as illustrated in the accompanying drawings.
Referring to
An imaging laser head 116 capable of emitting an imaging laser beam, and associated optics 118 for splitting the laser beam into an object and reference beam, respectively, and for directing the object and reference beam to the surface of the substrate 114, are positioned generally above, and spaced from, the imaging table 112. The laser head and is mounted on a track for movement along a pair of axes 120, 122 such that the laser head 116 is capable of being positioned over any point above the imaging table 112. The laser head is electrically connected to a power source (not shown) and a controller 124. As discussed in detail hereinafter, the controller 124 is configured to control the movement of the laser head 116 along the axes 120, 122. In addition, the controller is configured to control the angle and rotation of the laser beam, as well as the spacing of the point of interference of the beams from the substrate 112, according to an imaging parameter set for a given holographic image/optical element. The optics 118 may be of any type known in the art, and common to existing split beam imaging apparatuses, such as a plurality of lens or a multi-faceted crystal, although other optics may also be utilized without departing from the broader aspects of the present invention.
Each holographic image or optical element to be imaged is comprised of an array of holographic optical elements, i.e., pixels, each having a parameter set. The parameter set may include the angle of incidence and rotation of the object beam and reference beam with respect to the substrate necessary to produce the desired optical element of the particular holographic image being printed, as well as the spacing of the point of interference of the object and reference beams from the substrate 112. At the very basic level, each optical element may consist of a single pixel having a specific parameter set.
In an embodiment, the controller 118 has input/output capabilities such that a particular holographic image(s) or optical element(s) to be imaged can be created using known pixelizing software, such as bitmap imaging software, and input into the controller 118. The controller 118 is also configured to determine the parameter set for each optical element to be imaged once the overall holographic pattern is input into the controller 118, and to control movement of the laser head 116 (and orientation of the laser beam) and associated optics 118 to image the various holographic optical elements on the substrate 118 according to the parameter sets.
In particular, the laser head 116, controlled by the controller 118 according to the determined parameter sets of the various optical elements, emits a laser beam to create diffraction gratings or “scratches” on the substrate 112. As will be readily appreciated, it is this array of individual diffraction gratings in the surface of the substrate 112 that make up each optical element and create the overall desired optical effect of the holographic image. Importantly, the diffraction gratings are created in a digital manner, i.e., on a pixel-by-pixel basis across the substrate 112 until the entire optical element is imaged. Because the diffraction gratings are imaged on a pixel-by-pixel basis, optical elements of almost any desired orientation, size and shape, such as oblong, parallelogram and wave shape, may be imaged on a single substrate, in a single session on the imaging apparatus, without the need for mechanical recombination or like processes. Indeed, because of the pixel-by-pixel imaging, even optical elements that are entirely free-form may be imaged utilizing the holographic imaging apparatus 100 of the present invention.
With reference to
Whereas the circular prior art lens of
Moreover, by imaging on a pixel-by-pixel bases, the apparatus of the present invention is capable of creating holographic optical elements, consisting of an array diffraction gratings, that mimic the perceived optical effects of known optical elements such as the Fresnel lenses of
In particular, the imaging apparatus of the present invention, by the manner in which the diffraction gratings are produced on a pixel-by-pixel basis, is able to approximate complex optical elements that have heretofore only been capable of being produced in whole (e.g., through the imprinting of a Fresnel lens in a substrate as disclosed in the '533 patent). Moreover, the imaging apparatus of the present invention is thus capable of producing an integrated holographic pattern consisting of multiple similar or different optical elements utilizing a single step, single session process, i.e., without using a “step and repeat” process.
In an embodiment, the diffraction gratings 152 produced by the apparatus 100 of the present invention have a depth of approximately 1 micron, such that the surface of the substrate containing the optical elements/images appears and feels smooth. In addition, the depth of the diffraction gratings 152 is substantially the same across the entire sheet. Because of the very shallow depth of the diffraction gratings, and thus the optical elements themselves, the substrate on which the holographic images/optical elements are imaged may be substantially thin. As such, sheets containing holographic images produced in this manner have a variety of applications. This is in contrast to the prior art lens 10 of
Another advantage of the freeform holographic imaging apparatus of the present invention is the ability to imbed 3-dimensional text within a given optical element, such as a lens, during imaging. In addition, the apparatus of the present invention is capable of creating diffraction gratings that have the effect of changing the color of the image in dependence upon the angle from which it is viewed. In particular, by imaging on a pixel-by-pixel basis, distinct and particular colors, depending on the angle at which the images is viewed, can be created with certainty and almost unlimited flexibility. Indeed, one of the other artistic advantages resulting from the flexibility of the imaging apparatus of the present invention is that the resultant images contain more apparent “motion” that is viewable by an observer, which is not possible with more deeply imbedded images produced utilizing existing processes. As will be readily appreciated, all of this may be done without stopping operation of the apparatus to manually adjust components, reconfigure the apparatus, or the like.
By constructing a holographic image (i.e, optical element) on a pixel-by-pixel basis utilizing diffraction gratings in the surface of a substrate, numerous benefits may be realized. For example, as alluded to above, the substrate used may be relatively thin, on the order of 1-2 microns, in contrast to surface relief holographic/optical elements which require much thicker, more resilient and expensive substrates. In addition, holographic images of any shape and size (i.e., freeform) may be created, including holographic images that mimic almost any optical effect desired, such as that of a lens. Moreover, multiple repeated or separate images may be imaged on a single substrate in a single session on the apparatus by loading the layout of the images into the controller prior to imaging.
Moreover, by constructing holographic images on a pixel-by-pixel basis utilizing diffraction gratings in the surface of a substrate, there are no demarcation or recombine lines on the substrate between each individual image. Accordingly, the resultant integrated holographic pattern appears seamless and offers a more appealing visual experience for a viewer, in contrast to existing “step and repeat” methods which leave visible lines between each image.
Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those of skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of this disclosure.
