The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Yoshio Hayasaki - One of the best experts on this subject based on the ideXlab platform.
-
In-system optimization of a hologram for high-stability parallel Laser Processing.
Optics Letters, 2020Co-Authors: Honghao Zhang, Hidetomo Takahashi, Satoshi Hasegawa, Haruyoshi Toyoda, Yoshio HayasakiAbstract:A method for optimizing a computer-generated hologram (CGH) for high-stability Laser Processing is proposed. The CGH is optimized during Laser Processing; therefore, unpredicted dynamic changes in the Laser Processing system, in addition to its static imperfections, are automatically compensated for by exploiting the rewritable capability of the spatial light modulator. Consequently, the short-term and long-term stability are improved, which will contribute to the realization of high-speed, high-precision Laser Processing. A CGH that generated 36 parallel beams was continuously optimized, and the maximum uniformity reached 0.98, which is higher than reported in previous research. To the best of our knowledge, this is the first demonstration of gradual improvement of parallel Laser Processing with in-process optimization of the CGH. Furthermore, it was also demonstrated that the performance of the Laser Processing system against unexpected disturbances was improved.
-
In-system optimization of hologram for holographic femtosecond Laser Processing
Holography Diffractive Optics and Applications IX, 2019Co-Authors: Honghao Zhang, Satoshi Hasegawa, Yoshio HayasakiAbstract:We proposed a holographic Laser Processing system with the combination of femtosecond Laser and the in-system optimization. Femtosecond Laser Processing that employ a computer-generated hologram (CGH) displayed on a liquid-crystal-on-silicon spatial light modulator (LCOS-SLM), called holographic femtosecond Laser Processing (HFLP). Due to the inherent aberrations of the actual optical system, the diffraction peaks of holographic femtosecond Laser Processing has non-uniformity. To overcome this problem, we demonstrated a method called in-system optimization that optimizing the uniformity of the diffraction peaks while conducting the Laser Processing simultaneously. By taking advantage of the rewritable capability of the LCOS-SLM, with finite times of iteration perform of the in-system optimization, we obtained uniform peaks of 0.96, when the maximum intensity at the peaks of the diffraction spots was normalized to 1.0. Make use of this system, we realized the high efficiency and uniformity of Laser Processing, and made compensation for part of the inherent aberration in the optical system. In particular, we believe it can not only effectively avoid the impact of environmental factors on the Processing system and will greatly improve the Processing efficiency and stability, in the meanwhile, it will be widely applied for precise Laser Processing in the future.
-
In-process debris removal in femtosecond Laser Processing
Applied Physics A, 2017Co-Authors: Tetsuya Abe, Michiharu Ota, Hidetomo Takahashi, Satoshi Hasegawa, Yoshio HayasakiAbstract:Debris deposited around Laser-processed structures, which is a critical issue in high-precision Laser Processing, should be removed. A new method for Laser cleaning of debris was developed. A glass surface was irradiated with a line-focused beam for Laser cleaning, together with a focused beam for Laser Processing. Both beams were formed by computer-generated holograms (CGHs) displayed on a spatial light modulator. The distance between the two beams was controlled with the CGHs, and the time difference was controlled with an optical delay line. These optical structures were the novel aspect of our Laser Processing system. When two beams were superposed at the same position on a sample, we did not find a suitable beam parameter for debris removal, but we found that the Processing area was spatially enlarged depending on the temporal overlap. In contrast, when two beams separated by an adequate distance were radiated on a sample, we found suitable beam parameters for debris removal. Debris removal was effectively performed when the scanning speed of the Laser beams was low, because the low scanning speed produced a temperature higher than the glass transition temperature, and the heated and melted debris was ablated due to a smaller ablation threshold than that of the glass substrate. This in-process Laser debris removal method has the advantages of needing no additional equipment other than the optics, no additional operations, no special materials, and no specific operating environment.
-
Massively parallel femtosecond Laser Processing.
Optics Express, 2016Co-Authors: Satoshi Hasegawa, Haruyoshi Toyoda, Yoshio HayasakiAbstract:Massively parallel femtosecond Laser Processing with more than 1000 beams was demonstrated. Parallel beams were generated by a computer-generated hologram (CGH) displayed on a spatial light modulator (SLM). The key to this technique is to optimize the CGH in the Laser Processing system using a scheme called in-system optimization. It was analytically demonstrated that the number of beams is determined by the horizontal number of pixels in the SLM NSLM that is imaged at the pupil plane of an objective lens and a distance parameter pd obtained by dividing the distance between adjacent beams by the diffraction-limited beam diameter. A performance limitation of parallel Laser Processing in our system was estimated at NSLM of 250 and pd of 7.0. Based on these parameters, the maximum number of beams in a hexagonal close-packed structure was calculated to be 1189 by using an analytical equation.
-
Ultrafast Laser Processing of materials: from science to industry
Light: Science & Applications, 2016Co-Authors: Mangirdas Malinauskas, Yoshio Hayasaki, Satoshi Hasegawa, Albertas Žukauskas, Vygantas Mizeikis, Ričardas Buividas, Saulius JuodkazisAbstract:The ability of femtosecond Lasers to efficiently fabricate complex structures and devices for a wide variety of applications is reviewed. Mangirdas Malinauskas at Vilnius University in Lithuania and co-workers in Japan, Australia and Saudi Arabia describe how state-of-the-art Laser Processing techniques with ultrashort light pulses can be used to structure materials with a sub-micrometre resolution. Direct Laser writing of suitable photoresists and other transparent media can create intricate three-dimensional photonic crystals, micro-optical components, gratings, tissue scaffolds and optical waveguides. Such structures are potentially useful for empowering next-generation applications in telecommunications and bioengineering that rely on the creation of increasingly sophisticated miniature parts. The precision, fabrication speed and versatility of ultrafast Laser Processing make it well placed to become a vital industrial tool for manufacturing. Processing of materials by ultrashort Laser pulses has evolved significantly over the last decade and is starting to reveal its scientific, technological and industrial potential. In ultrafast Laser manufacturing, optical energy of tightly focused femtosecond or picosecond Laser pulses can be delivered to precisely defined positions in the bulk of materials via two-/multi-photon excitation on a timescale much faster than thermal energy exchange between photoexcited electrons and lattice ions. Control of photo-ionization and thermal processes with the highest precision, inducing local photomodification in sub-100-nm-sized regions has been achieved. State-of-the-art ultrashort Laser Processing techniques exploit high 0.1–1 μm spatial resolution and almost unrestricted three-dimensional structuring capability. Adjustable pulse duration, spatiotemporal chirp, phase front tilt and polarization allow control of photomodification via uniquely wide parameter space. Mature opto-electrical/mechanical technologies have enabled Laser Processing speeds approaching meters-per-second, leading to a fast lab-to-fab transfer. The key aspects and latest achievements are reviewed with an emphasis on the fundamental relation between spatial resolution and total fabrication throughput. Emerging biomedical applications implementing micrometer feature precision over centimeter-scale scaffolds and photonic wire bonding in telecommunications are highlighted.
Satoshi Hasegawa - One of the best experts on this subject based on the ideXlab platform.
-
In-system optimization of a hologram for high-stability parallel Laser Processing.
Optics Letters, 2020Co-Authors: Honghao Zhang, Hidetomo Takahashi, Satoshi Hasegawa, Haruyoshi Toyoda, Yoshio HayasakiAbstract:A method for optimizing a computer-generated hologram (CGH) for high-stability Laser Processing is proposed. The CGH is optimized during Laser Processing; therefore, unpredicted dynamic changes in the Laser Processing system, in addition to its static imperfections, are automatically compensated for by exploiting the rewritable capability of the spatial light modulator. Consequently, the short-term and long-term stability are improved, which will contribute to the realization of high-speed, high-precision Laser Processing. A CGH that generated 36 parallel beams was continuously optimized, and the maximum uniformity reached 0.98, which is higher than reported in previous research. To the best of our knowledge, this is the first demonstration of gradual improvement of parallel Laser Processing with in-process optimization of the CGH. Furthermore, it was also demonstrated that the performance of the Laser Processing system against unexpected disturbances was improved.
-
In-system optimization of hologram for holographic femtosecond Laser Processing
Holography Diffractive Optics and Applications IX, 2019Co-Authors: Honghao Zhang, Satoshi Hasegawa, Yoshio HayasakiAbstract:We proposed a holographic Laser Processing system with the combination of femtosecond Laser and the in-system optimization. Femtosecond Laser Processing that employ a computer-generated hologram (CGH) displayed on a liquid-crystal-on-silicon spatial light modulator (LCOS-SLM), called holographic femtosecond Laser Processing (HFLP). Due to the inherent aberrations of the actual optical system, the diffraction peaks of holographic femtosecond Laser Processing has non-uniformity. To overcome this problem, we demonstrated a method called in-system optimization that optimizing the uniformity of the diffraction peaks while conducting the Laser Processing simultaneously. By taking advantage of the rewritable capability of the LCOS-SLM, with finite times of iteration perform of the in-system optimization, we obtained uniform peaks of 0.96, when the maximum intensity at the peaks of the diffraction spots was normalized to 1.0. Make use of this system, we realized the high efficiency and uniformity of Laser Processing, and made compensation for part of the inherent aberration in the optical system. In particular, we believe it can not only effectively avoid the impact of environmental factors on the Processing system and will greatly improve the Processing efficiency and stability, in the meanwhile, it will be widely applied for precise Laser Processing in the future.
-
In-process debris removal in femtosecond Laser Processing
Applied Physics A, 2017Co-Authors: Tetsuya Abe, Michiharu Ota, Hidetomo Takahashi, Satoshi Hasegawa, Yoshio HayasakiAbstract:Debris deposited around Laser-processed structures, which is a critical issue in high-precision Laser Processing, should be removed. A new method for Laser cleaning of debris was developed. A glass surface was irradiated with a line-focused beam for Laser cleaning, together with a focused beam for Laser Processing. Both beams were formed by computer-generated holograms (CGHs) displayed on a spatial light modulator. The distance between the two beams was controlled with the CGHs, and the time difference was controlled with an optical delay line. These optical structures were the novel aspect of our Laser Processing system. When two beams were superposed at the same position on a sample, we did not find a suitable beam parameter for debris removal, but we found that the Processing area was spatially enlarged depending on the temporal overlap. In contrast, when two beams separated by an adequate distance were radiated on a sample, we found suitable beam parameters for debris removal. Debris removal was effectively performed when the scanning speed of the Laser beams was low, because the low scanning speed produced a temperature higher than the glass transition temperature, and the heated and melted debris was ablated due to a smaller ablation threshold than that of the glass substrate. This in-process Laser debris removal method has the advantages of needing no additional equipment other than the optics, no additional operations, no special materials, and no specific operating environment.
-
Massively parallel femtosecond Laser Processing.
Optics Express, 2016Co-Authors: Satoshi Hasegawa, Haruyoshi Toyoda, Yoshio HayasakiAbstract:Massively parallel femtosecond Laser Processing with more than 1000 beams was demonstrated. Parallel beams were generated by a computer-generated hologram (CGH) displayed on a spatial light modulator (SLM). The key to this technique is to optimize the CGH in the Laser Processing system using a scheme called in-system optimization. It was analytically demonstrated that the number of beams is determined by the horizontal number of pixels in the SLM NSLM that is imaged at the pupil plane of an objective lens and a distance parameter pd obtained by dividing the distance between adjacent beams by the diffraction-limited beam diameter. A performance limitation of parallel Laser Processing in our system was estimated at NSLM of 250 and pd of 7.0. Based on these parameters, the maximum number of beams in a hexagonal close-packed structure was calculated to be 1189 by using an analytical equation.
-
Ultrafast Laser Processing of materials: from science to industry
Light: Science & Applications, 2016Co-Authors: Mangirdas Malinauskas, Yoshio Hayasaki, Satoshi Hasegawa, Albertas Žukauskas, Vygantas Mizeikis, Ričardas Buividas, Saulius JuodkazisAbstract:The ability of femtosecond Lasers to efficiently fabricate complex structures and devices for a wide variety of applications is reviewed. Mangirdas Malinauskas at Vilnius University in Lithuania and co-workers in Japan, Australia and Saudi Arabia describe how state-of-the-art Laser Processing techniques with ultrashort light pulses can be used to structure materials with a sub-micrometre resolution. Direct Laser writing of suitable photoresists and other transparent media can create intricate three-dimensional photonic crystals, micro-optical components, gratings, tissue scaffolds and optical waveguides. Such structures are potentially useful for empowering next-generation applications in telecommunications and bioengineering that rely on the creation of increasingly sophisticated miniature parts. The precision, fabrication speed and versatility of ultrafast Laser Processing make it well placed to become a vital industrial tool for manufacturing. Processing of materials by ultrashort Laser pulses has evolved significantly over the last decade and is starting to reveal its scientific, technological and industrial potential. In ultrafast Laser manufacturing, optical energy of tightly focused femtosecond or picosecond Laser pulses can be delivered to precisely defined positions in the bulk of materials via two-/multi-photon excitation on a timescale much faster than thermal energy exchange between photoexcited electrons and lattice ions. Control of photo-ionization and thermal processes with the highest precision, inducing local photomodification in sub-100-nm-sized regions has been achieved. State-of-the-art ultrashort Laser Processing techniques exploit high 0.1–1 μm spatial resolution and almost unrestricted three-dimensional structuring capability. Adjustable pulse duration, spatiotemporal chirp, phase front tilt and polarization allow control of photomodification via uniquely wide parameter space. Mature opto-electrical/mechanical technologies have enabled Laser Processing speeds approaching meters-per-second, leading to a fast lab-to-fab transfer. The key aspects and latest achievements are reviewed with an emphasis on the fundamental relation between spatial resolution and total fabrication throughput. Emerging biomedical applications implementing micrometer feature precision over centimeter-scale scaffolds and photonic wire bonding in telecommunications are highlighted.
Rolf Brendel - One of the best experts on this subject based on the ideXlab platform.
-
Increased Front Surface Recombination by Rear-Side Laser Processing on Thin Silicon Solar Cells
IEEE Journal of Photovoltaics, 2013Co-Authors: Felix Haase, Sarah Kajari-schröder, Udo Römer, Tobias Neubert, Jan-hendrik Petermann, Robby Peibst, Nils-peter Harder, Rolf BrendelAbstract:We show the degradation of the front surface passivation by rear-side Laser Processing of thin silicon solar cells when using a Laser with a pulse length of 8 ps. 45-μm-thick back-contact back-junction monocrystalline silicon solar cells show an energy conversion efficiency of 18.8% without rear-side Laser Processing, whereas they show only 7.5% with an additional rear-side Laser process step for contact separation. This low efficiency is due to the degradation of the front surface passivation, which is confirmed by quantum efficiency measurements. The internal quantum efficiency at short wavelength is 0.88 without Laser Processing, whereas it is only 0.33 with the rear-side Laser process step.
Nobuo Nishida - One of the best experts on this subject based on the ideXlab platform.
-
variable holographic femtosecond Laser Processing by use of a spatial light modulator
Applied Physics Letters, 2005Co-Authors: Yoshio Hayasaki, Takashi Sugimoto, Akihiro Takita, Nobuo NishidaAbstract:We propose a holographic femtosecond Laser Processing system capable of parallel, arbitrary, and variable patterning. These features are achieved by introducing a spatial light modulator displaying a hologram into the femtosecond Laser Processing system. We demonstrate the variable parallel Processing of a glass sample.
Felix Haase - One of the best experts on this subject based on the ideXlab platform.
-
Increased Front Surface Recombination by Rear-Side Laser Processing on Thin Silicon Solar Cells
IEEE Journal of Photovoltaics, 2013Co-Authors: Felix Haase, Sarah Kajari-schröder, Udo Römer, Tobias Neubert, Jan-hendrik Petermann, Robby Peibst, Nils-peter Harder, Rolf BrendelAbstract:We show the degradation of the front surface passivation by rear-side Laser Processing of thin silicon solar cells when using a Laser with a pulse length of 8 ps. 45-μm-thick back-contact back-junction monocrystalline silicon solar cells show an energy conversion efficiency of 18.8% without rear-side Laser Processing, whereas they show only 7.5% with an additional rear-side Laser process step for contact separation. This low efficiency is due to the degradation of the front surface passivation, which is confirmed by quantum efficiency measurements. The internal quantum efficiency at short wavelength is 0.88 without Laser Processing, whereas it is only 0.33 with the rear-side Laser process step.
