Takayuki Hoshi

Satoshi Hashizume, Amy Koike, Takayuki Hoshi et al.

In this paper, a method of rendering aerial haptics that uses an aerodynamic vortex and focused ultrasound is presented. Significant research has been conducted on haptic applications based on multiple phenomena such as magnetic and electric fields, focused ultrasound, and laser plasma. By combining multiple physical quantities; the resolution, distance, and magnitude of force are enhanced. To combine multiple tactile technologies, basic experiments on resolution and discrimination threshold are required. Separate user studies were conducted using aerodynamic and ultrasonic haptics. Moreover, the perception of their superposition, in addition to their resolution, was tested. Although these fields cause no direct interference, the system enables the simultaneous perception of the tactile feedback of both stimuli. The results of this study are expected to contribute to expanding the expression of aerial haptic displays based on several principles.

Yoichi Ochiai, Kota Kumagai, Takayuki Hoshi et al.

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.