A holographic printer is a device that prints three-dimensional images of an object with the help of laser light. They are much more complex devices when compared to two-dimensional printers and are far more expensive. Holographic printers are used in many industries to check currency counterfeiting and authenticate sensitive documents such as checks, debit cards, and product labels. Many high-quality holographic printers are available in the market commercially, making it possible to print three-dimensional images in full color and high resolution.
Holographic printing used to be a challenging area because an actual physical object was required to produce a hologram. This wasn't a viable technique, and further research concentrated on finding a way to optically combine information from multiple photographs from varying views. Data obtained from normal sequential photos of an object were used to create an intermediate hologram on a liquid crystal display screen or LCD. No physical objects were needed in this approach. This optical image acted as the master from which other holograms could be printed with the aid of holographic printers.
Printing methodologies that need an intermediate hologram from which the final hologram can be obtained are referred to as two-step holographic printing. A one-step holographic printing scheme in which a viable, viewable hologram is created without the need for an intermediate image was also developed. Both approaches have their advantages and disadvantages. The two-step printing process requires sensitive materials and uses wet processing in contrast to the one-step system, which requires only dry processing and uses materials like photopolymers. Holograms generated in a single-step process may suffer from pixelation, an issue that is not that likely to occur in a two-step holographic printing process.
Holographic printers have adjustable slits on both sides and are made in such a way that no shadows can be projected onto the film plate. Pulsed laser lights are used to read the image off the LCD to produce a complex, three-dimensional image that is printed. The final holographic print can be viewed in ordinary white light, and the same image is visible from different angles.
Digital pictures provide the data that digital holographic printers use to create 3-D holograms, so the final images may have a pixelated appearance. These holographic printers use pulsed blue, green, and red laser beams to convert a series of images into a hologram that is printed onto photosensitive material. The digital data used to create the master hologram can come from either a real-life object or from a 3-D virtual object. The data can also be manipulated mathematically to correct errors that result in optical distortion.