Fairy Lights in Femtoseconds: Aerial and Volumetric Graphics Rendered by Focused Femtosecond Laser Combined with Computational Holographic Fields (1506.06668v1)

Abstract: We present a method of rendering aerial and volumetric graphics using femtosecond lasers. A high-intensity laser excites a physical matter to emit light at an arbitrary 3D position. Popular applications can then be explored especially since plasma induced by a femtosecond laser is safer than that generated by a nanosecond laser. There are two methods of rendering graphics with a femtosecond laser in air: Producing holograms using spatial light modulation technology, and scanning of a laser beam by a galvano mirror. The holograms and workspace of the system proposed here occupy a volume of up to 1 cm^3; however, this size is scalable depending on the optical devices and their setup. This paper provides details of the principles, system setup, and experimental evaluation, and discussions on scalability, design space, and applications of this system. We tested two laser sources: an adjustable (30-100 fs) laser which projects up to 1,000 pulses per second at energy up to 7 mJ per pulse, and a 269-fs laser which projects up to 200,000 pulses per second at an energy up to 50 uJ per pulse. We confirmed that the spatiotemporal resolution of volumetric displays, implemented with these laser sources, is 4,000 and 200,000 dots per second. Although we focus on laser-induced plasma in air, the discussion presented here is also applicable to other rendering principles such as fluorescence and microbubble in solid/liquid materials.

• The paper presents a novel approach using femtosecond lasers to induce plasma and render 3D aerial and volumetric graphics with up to 200,000 dots per second.
• It leverages spatial light modulators and galvano mirror scanning to significantly enhance resolution compared to nanosecond laser methods.
• The study addresses safety by confirming minimal skin risks with ultra-short pulses while emphasizing retinal protection and safe user interaction.

Aerial and Volumetric Graphics via Laser-Induced Plasma

This document presents an in-depth examination of employing femtosecond lasers in the rendering of volumetric and aerial graphics. The fundamental premise is the utilization of high-intensity femtosecond lasers to excite physical matter, namely air, to emit light at pre-defined three-dimensional (3D) positions. This method leverages the safer properties of plasma induced by femtosecond lasers when compared to nanosecond lasers. The notable methodologies employed include generating holographic fields using spatial light modulators (SLMs) and scanning laser beams with galvano mirrors. The experimental setup discussed achieves rendering in volumes up to 1 cm³, scalable with modifications in optical setups.

Experimental Setup and Results

Two laser systems were evaluated, with varying pulse durations and energy outputs. First, an adjustable femtosecond laser delivering 30-100 fs pulses and a second system utilizing a fixed 269 fs laser. The effective spatiotemporal resolutions were measured at 4,000 and 200,000 dots per second, respectively, for each method. Practical experiments confirmed the substantial capability enhancements over antecedent nanosecond-based systems wherein the rendering performance reached 1,000 dots per second at most.

The paper methodically explicates the optical principles, such as laser-induced plasma and the resultant tunnel ionization effect, emphasizing that such processes achieve target ionization thresholds essential for rendering precise image voxels. Furthermore, the experimental section evaluates the influence of energy levels and pulse duration on brightness, establishing a direct correlation between energy concentration and resultant intensity.

Safety and Interaction Considerations

A key contribution lies in addressing safety concerns pertinent to human interaction with laser-induced plasma displays. The research indicates that the direct implications to human skin are mitigated due to the ultra-short pulse duration, minimizing potential harm. However, retinal safety necessitates protective eyewear until further maturation in the technology is attained. Additionally, interaction possibilities afford intriguing touch-based interfaces, albeit the plasma's tangible presence warrants careful handling.

Implications and Future Directions

From a theoretical standpoint, the integration of femtosecond lasers with SLMs propels the volume graphics domain nearer to creating high-resolution and interactive 3D displays. The work underscores the potential broader applications, including augmented reality and volumetric display technology, with practical implications such as real-time aerial user interfaces and tangible digital interactions.

Moving forward, scalability remains a pressing concern, particularly enhancing the workspace and voxel density. The authors propose enhancements in optical components, suggesting a trajectory toward higher power laser sources with shortened pulse widths. Achieving a sustainable increase in display resolution and vitality could enable these systems to transition from experimental to ubiquitous in commercial technology applications.

In summary, this research enriches the academic dialogue surrounding laser-induced plasma displays by providing a comprehensive exploration of the potentials and limitations of femtosecond laser applications in volumetric displays. Further developments in this technological niche hold promise for revolutionizing 3D display methodologies, with significant implications for various interactive digital media fields.