成果報告書詳細
管理番号20120000000700
タイトル*平成22年度中間年報 省エネルギー革新技術開発事業/先導研究/大面積ナノ構造材料創製用高出力超短パルスレーザー装置の研究開発
公開日2012/6/20
報告書年度2010 - 2010
委託先名サイバーレーザー株式会社
プロジェクト番号P09015
部署名省エネルギー部
和文要約和文要約等以下本編抜粋:
1. 研究開発の内容及び成果等
自動車エンジン内部の機械駆動系の摩擦損失低減、航空機や自動車のボディを外部汚染から守る表面活性をナノ周期構造の作製により実現することで、省エネ効果を達成することができる。本申請テーマにおいては、このナノ周期構造の作製を産業で使用できるレベルにするために、下記の課題を克服する。
英文要約In this research program Cyber Laser inc. develops a high power and high repetition rate ultra short pulse laser of which output pulse irradiation can create nano-periodic structures on various material surfaces with a high processing speed. Such nano-periodic structure has been attracting a lot of researcher’s interest to apply it to obtain industrial benefits such as reduction of dynamic friction loss in the mechanical motion parts in the automobile engine and avoiding of soiling on the surface of vehicles and airplanes. In the second year of the program, we demonstrated nano-periodic structure processing with the processing speed of 75 mm2/s. We also started to process nano-periodic structure on transparent materials including glass plates, successfully stabilized the output power of a femtosecond laser system at 5 W, demonstrated a 3-pico-sec regenerative amplifier with an output power of over 35 W, and generated 5% of UV photons from a developed femtosecond laser.
On the basis of an experiment to investigate the processing energy for nano-periodic structure, we designed and employed an optical system to expand laser beam using three cylindrical lenses. Using a pulsed laser beam with a wavelength of 780 nm, and a pulse energy of 0.054 mJ, nano-periodic structure was created on a 300 x 300 mm stainless steel plate with a speed of 75 mm2/s was carried out.
In order to effectively create the nano-periodic structures a laser beam was unidirectionally expanded by a cylindrical lens with a focal length of 40 mm in order to use pulse energy efficiently, and it was scanned at the speed of 1.3 mm/s onto a gallium nitride thin film with the pulse energy of 0.292 mJ. As a result, we succeeded in fabricating nano-periodic structures on a surface of a transparent material.
 We demonstrated the long term operation test using a high power femtosecond laser. We have found out that the some optical components in the amplifier cavity might be slightly distorted due to the heat accumulation originated by its high power density. We re-designed the cavity configuration to reduce the laser fluences on the optics, compared with the stable 3-W output operation. After that, we have achieved stable 5-W operation in 100 hours.
We have developed a Yb:YAG thin disk based regenerative amplifier system. We have designed the amplifier cavity not only to match the spatial mode size on the disk to pump region but also to reduce nonlinearity in the amplifier. As a result, we have achieved up to 35-W amplified power with the pulse duration of 2.34 ps.
In order to apply to processing transparent materials we need to generate the laser pulses with the wavelength of 260 nm by using 2.4-W femtosecond laser pulses with wavelength of 780 nm and a repetition rate of 50 kHz. The second harmonic laser and the 780nm laser were focused to a BBO nonlinear crystal to generate the third harmonic photons with the output power of 160 mW and the conversion efficiency of 6.6%.
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