【Explanation and Application of Optical Hologram Technology 】
Optical holography is a technique that records and reconstructs wavefront information of object light by utilizing interference and diffraction. However, the technology we have established takes a different approach from conventional holograms that record interference fringes using laser light. Our group uses printing plates to design and create a fine, sand-grain-like microstructure through a combination of transparent regions and opaque mask patterns. This achieves an optical effect where a specific image appears when observed through a point light source such as an LED.
The optical principle, reconstruction conditions, structural design, and future applications of this technology are outlined below.
1. Features and Components of the Technology
Our group’s optical film technology leverages advanced drawing and photosensitive material processing techniques cultivated in the printing plate field. By designing and forming high-density transparent and opaque patterns on photographic printing films, we achieve an image reconstruction function.
This film features a fine, seemingly random, sand-grain-like pattern, which is generated based on the designed image information. By selecting a point light source, such as an LED, and viewing the film from a specific observation angle and distance, light is either blocked or transmitted by the mask patterns, forming a specific image on the viewer’s retina.
2. Optical Principle
This technology is based on wave optics, involving the interference and diffraction of light waves. The distribution of transparent and opaque areas on the film controls the propagation of light, dictating which direction light from a point source travels and where it forms an image. Conversely, a hologram controls light waves to form a desired image at a desired position. We design the sand-grain pattern of the hologram by performing calculations on the diffraction propagation of light waves.
3. Sand-Grain Pattern and Information Density
The sand-grain pattern refers to the intricate and irregular pattern applied across the entire film. It requires an extremely high information density to form a visible image. This pattern itself is not a simple collection of dots but is composed of optimized pixel groups corresponding to specific light directions and transparencies. Consequently, the image is not visible under normal visible light illumination conditions but possesses a high degree of selectivity, only appearing under specific point light source conditions.
This enables the conferral of advanced security and artistic effects to products.
4. Reconstruction Conditions and Engineering Aspects of Design
To reconstruct images using this technology, the following conditions must be precisely controlled:
・Directivity and illumination position of the point light source
・Drawing resolution and contrast of the film
・Size and density of transparent/opaque patterns
・Viewer’s angle of sight and distance
Specifically, the film drawing utilizes conventional printing plate technology, allowing for control over drawing at a 1-micron level. This resolution enables the reproduction of extremely detailed images and text, making it highly effective for design protection and anti-copying measures.
Furthermore, the manufacturing process incorporates halftone processing using photosensitive materials like positive/negative films, as well as positioning calculations using image synthesis software. This represents cutting-edge technology resulting from the fusion of optics, graphics, and printing plate engineering.
5. Application Fields and Possibilities
This technology is expected to be applied in the following areas:
・High-security labels for anti-counterfeiting
・Decorative hologram patches to enhance brand value
・Adding dynamic optical effects to limited edition products and art pieces
・Authentication trigger displays integrated into packaging
・Spatial imagery for interactive exhibits
Looking ahead, we envision further integration with AR (Augmented Reality) and composite processing with technologies like inkjet printing. We expect this to become a next-generation visual information transmission medium that merges analog and digital.
Our group’s sand-grain hologram film technology is a fusion of printing plate technology and optical drawing techniques. We are confident that this technology, which selectively forms visible images by controlling light transmission and blocking, will play a significant role in the fields of security, artistic expression, and display in the future.