Hologram Exposure Device with Beam Reduction for Small Hogels
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Solution Overview
Problem
Current holographic printers are limited in producing holograms with small hogel sizes and large optical angles, which restricts the creation of high-quality three-dimensional representations and holographic optical elements with varied optical functions, especially for applications like head-up displays and data goggles.
Innovation Solution
An exposure device with a modulation unit, reduction unit, and objective lens unit that produces a modified laser beam with a smaller beam diameter and high numerical aperture, allowing for the recording of holograms with hogels as small as 100-200 μm and angles of incidence and reflection up to ±90°, enabling the production of holographic optical elements with diverse optical functions and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional holographic printers are used, then holograms can be produced, but the hogel size is limited to minimum 200-500 μm and optical angles are limited to ±40°
Solution Approach 1:
The patent applies segmentation by dividing the hologram recording into sequential sub-holograms (hogels) that are written one after another. This allows each hogel to be precisely controlled with small beam diameters, achieving hogel sizes of 100-200 μm while maintaining the ability to cover large angular ranges through sequential positioning and varying beam angles during the sequential writing process.
2Manufacturing precision
If laser beams with very small beam diameters are used for sequential recording, then hogel size can be reduced to 100-200 μm, but the optical angles are traditionally limited
Solution Approach 1:
The patent employs dynamics by making the beam parameters dynamic during sequential recording. The beam diameter, beam angle, and positioning are continuously adjusted during the sequential writing process, allowing small beam diameters (for precise hogel sizing) to be combined with varying beam angles (for achieving ±90° optical angles). This dynamic control enables both precise hogel dimensions and wide angular coverage.
3Productivity
If large-scale recording is used to illuminate the entire holographic layer, then the complete hologram is recorded at once, but significantly higher laser power is required
Solution Approach 1:
The patent applies partial action by recording the hologram in sequential steps, writing only a portion (one hogel at a time) rather than illuminating the entire holographic layer simultaneously. This partial sequential approach dramatically reduces the laser power required at any given moment compared to large-scale simultaneous recording, while still achieving complete hologram recording through the sequential process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device enables the creation of holograms with very large optical angles and varied optical functions, improving image quality and enabling the production of reflection and transmission holograms, including waveguide structures, beyond the limitations of previous technologies.
Implementation Method 1
at least one modulation unit, which is designed to produce 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
Implementation Method 2
at least one reduction unit, which is designed to produce a modified modulation beam using the modulation beam, the modified modulation beam having a smaller beam diameter than the modulation beam
Implementation Method 3
at least one objective lens unit, which is designed to direct the modulated 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
Implementation Method 4
two laser sources (reference wave and object wave) coherent relative to one another are caused to interfere on a photosensitive holographic layer. The resulting interference pattern is then written into the holographic layer
Implementation Method 5
two laser sources (reference wave and object wave) coherent relative to one another are caused to interfere on a photosensitive holographic layer
Implementation Method 6
two laser sources (reference wave and object wave) coherent relative to one another are caused to interfere on a photosensitive holographic layer. The resulting interference pattern is then written into the holographic layer
Data Source
AI summary
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.