Product Code: ICAL05_M504

Analysis of Microspike Array Formation on Tungsten Surface with Femtosecond Laser
Authors:
Etsuji Ohmura, Osaka University; Suita Osaka Japan
Yasumitsu Nomura, Osaka University; Suita Osaka Japan
Hiroyuki Hayashi, Osaka University; Suita Osaka Japan
Tomokazu Sano, Osaka University; Suita Osaka Japan
Yoshinori Hirata, Osaka University; Suita Osaka Japan
Presented at ICALEO 2005

Microspike array can be formed on a tungsten surface by irradiating a femtosecond laser through a very small aperture whose distance from the surface is order of the aperture size. Laser diffracts through the aperture. Therefore we analyzed the intensity distributions of diffracted laser on the surface of specimen. The diffraction is given by the integral formula of Fresnel and Kirchhoff. As a result the shape and the array of microspikes obtained by experiments were in good agreement with the calculated intensity distribution on the tungsten surface. The reflection of laser intensity distribution on microspike array is a distinctive feature of femtosecond laser, because the fusion and evaporation process induced by the ultrashort pulse duration is very much shorter than the diffusion time of heat. It was confirmed by measuring field emission current that such microspike array has a potential to be used for microemitter tips.