The large-aperture pulse compression grating(PCG) is a critical component in generating an ultra-high-intensity, ultra-short-pulse laser;however, the size of the PCG manufactured by transmission holographic exposure i...The large-aperture pulse compression grating(PCG) is a critical component in generating an ultra-high-intensity, ultra-short-pulse laser;however, the size of the PCG manufactured by transmission holographic exposure is limited to large-scale high-quality materials. The reflective method is a potential way for solving the size limitation, but there is still no successful precedent due to the lack of scientific specifications and advanced processing technology of exposure mirrors. In this paper, an analytical model is developed to clarify the specifications of components, and advanced processing technology is adopted to control the spatial frequency errors. Hereafter, we have successfully fabricated a multilayer dielectric grating of 200 mm × 150 mm by using an off-axis reflective exposure system with Φ300 mm. This demonstration proves that PCGs can be manufactured by using the reflection holographic exposure method and shows the potential for manufacturing the meter-level gratings used in 100 petawatt class high-power lasers.展开更多
Introduction: The laser is a high energy instrument which can melt metals like nitinol. So it is very important to know under which conditions it is dangerous to perform an endourologic lithotripsy. We measure the tem...Introduction: The laser is a high energy instrument which can melt metals like nitinol. So it is very important to know under which conditions it is dangerous to perform an endourologic lithotripsy. We measure the temperature increase during laser exposure in an underwater in-vitro ureter model. For comparison, temperatures with and without irrigation and with different distances from the laser fiber to the thermometer are measured. Materials and Methods: We used the Ho:YAG-laser (Vera PulseTM, Coherent) with a 365 μm laser fiber. The settings of the laser were 0.6 J with a frequency of 5 Hz which is the minimum setting for that type of laser. The experimental setup was closely aligned with the clinical situation. A metal container was filled with 0.9% sodium chloride (NaCl) solution (Temp. 36.8°) and a catheter with an inner diameter of 4 mm was attached to the rim of the container. The tip of the thermometer was attached inside the catheter through a waterproof hole. The laser fiber was guided by means of a rigid URS video device (11.5 F). We had four different settings during the measurement: 1) Distance of 0.5 cm between the laser and the thermometer;without irrigation, 2) Distance of 0.5 cm between the laser and the thermometer;with irrigation, 3) Distance of 1 cm between the laser and the thermometer;without irrigation, 4) Distance of 1 cm between the laser and the thermometer;with irrigation. Results: The maximum overall temperature was recorded in the 1) and 3) setting, both featuring no irrigation. The maximum temperature was ~50°C in both settings, with the 1) setting reaching the maximum temperature after 50 seconds and hence approximately twice as fast as the 3) setting. During measurements with a NaCl solution flow we couldn’t detect any noticeable increase in temperature, neither at short nor at long distance between the laser fiber and the thermometer. Conclusion: There is a relevant heating in the ureter beside an endourologic lithotripsy. In our model we could reproduce a maximum heating unt展开更多
Poly(methyl methacrylate)(PMMA) is widely used for graphene transfer and device fabrication.However,it inevitably leaves a thin layer of polymer residues after acetone rinsing and leads to dramatic degradation of devi...Poly(methyl methacrylate)(PMMA) is widely used for graphene transfer and device fabrication.However,it inevitably leaves a thin layer of polymer residues after acetone rinsing and leads to dramatic degradation of device performance.How to eliminate contamination and restore clean surfaces of graphene is still highly demanded.In this paper,we present a reliable and position-controllable method to remove the polymer residues on graphene films by laser exposure.Under proper laser conditions,PMMA residues can be substantially reduced without introducing defects to the underlying graphene.Furthermore,by applying this laser cleaning technique to the channel and contacts of graphene fieldeffect transistors(GFETs),higher carrier mobility as well as lower contact resistance can be realized.This work opens a way for probing intrinsic properties of contaminant-free graphene and fabricating high-performance GFETs with both clean channel and intimate graphene/metal contact.展开更多
Cyclic thermal exposure tests of infrared heating to 800 ℃ in 120 s followed by compressed air cooling to 150 ℃ in 60 s were performed for the laser deposited Ti60A （Ti5.54Al3.38Sn3.34Zr0.37Mo0.46Si） alloy. The ef...Cyclic thermal exposure tests of infrared heating to 800 ℃ in 120 s followed by compressed air cooling to 150 ℃ in 60 s were performed for the laser deposited Ti60A （Ti5.54Al3.38Sn3.34Zr0.37Mo0.46Si） alloy. The effects of thermal exposure cycles on length ofβphase, area fraction ofαphase and microhardness of alloy were examined by OM, SEM and EDS. The results indicate that thermal exposure cycles have significant effects on length ofβphase, area fraction ofαphase and microhardness of the alloy. The original fine basket-weaveβand 78.5%αtransform to transient wedge-likeβ, finally leaving granularβand 97.6%coarsenedαwith the increased thermal exposure cycles. The formation mechanism of coarsenedαand broken-upβmicrostructure is discussed. The alloy after 750 thermal exposure cycles has the maximum microhardness, 33.3%higher than that of the as-deposited alloy.展开更多
Experimental work has been focused on the formation of alloyed Au-Cu nanoparticles under simultaneous laser exposure and mechanical stirring of mixed monometallic colloids, here referred to as dual procedure. As a fee...Experimental work has been focused on the formation of alloyed Au-Cu nanoparticles under simultaneous laser exposure and mechanical stirring of mixed monometallic colloids, here referred to as dual procedure. As a feed for the dual procedure, Au and Cu monometallic nanoparticle colloids have been using a laser ablation technique. To accomplish this, bulk targets were ablated with 1064 nm wavelength Nd: YAG laser in a pure acetone(99.99%) environment. Ultraviolet-visible optical absorption spectrometry, transmission electron microscopy, X-ray diffraction and X-ray fluorescence technique have been used to characterize the nanoparticles. It has been found that experimental conditions such as stirring and laser parameters strongly affect the synthesized particle properties, including the size, shape, composition and stability of the nanoparticles. Alloy nanoparticles containing 39% Au – 61% Cu have also been prepared in the same process, but in two forms of a homogeneous alloy and a core-shell structure.展开更多
Plasma X-ray sources for biological microscopy have been produced by focusing single shots from Nd:glass laser onto carbon rod targets at irradiances between 1 × 1013 W⋅cm−2 and 3 × 1013 W...Plasma X-ray sources for biological microscopy have been produced by focusing single shots from Nd:glass laser onto carbon rod targets at irradiances between 1 × 1013 W⋅cm−2 and 3 × 1013 W⋅cm−2 to expose test objects. The optimum parameters needed for obtaining high accurate information on the samples under test namely: the minimum energies and irradiances at a range of angles between the incoming laser beam and the normal to the resist, the depth of exposure of the photoresist as a function of incident laser energy (and irradiance) were concluded in this work.展开更多
基金supported by the National Key R&D Program of China(2020YFA0714500)the National Natural Science Youth Foundation of China(62205352)+5 种基金the Member of Youth Innovation Promotion Association of the Chinese Academy of Sciencesthe International Partnership Program of the Chinese Academy of Sciences(181231KYSB20200040)the Chinese Academy of Sciences President’s International Fellowship Initiative(2023VMB0008)the Shanghai Sailing Program(20YF1454800)the Natural Science Foundation of Shanghai(21ZR1472000)the Shanghai Strategic Emerging Industry Development Special Fund(31011442501217020191D3101001)。
文摘The large-aperture pulse compression grating(PCG) is a critical component in generating an ultra-high-intensity, ultra-short-pulse laser;however, the size of the PCG manufactured by transmission holographic exposure is limited to large-scale high-quality materials. The reflective method is a potential way for solving the size limitation, but there is still no successful precedent due to the lack of scientific specifications and advanced processing technology of exposure mirrors. In this paper, an analytical model is developed to clarify the specifications of components, and advanced processing technology is adopted to control the spatial frequency errors. Hereafter, we have successfully fabricated a multilayer dielectric grating of 200 mm × 150 mm by using an off-axis reflective exposure system with Φ300 mm. This demonstration proves that PCGs can be manufactured by using the reflection holographic exposure method and shows the potential for manufacturing the meter-level gratings used in 100 petawatt class high-power lasers.
文摘Introduction: The laser is a high energy instrument which can melt metals like nitinol. So it is very important to know under which conditions it is dangerous to perform an endourologic lithotripsy. We measure the temperature increase during laser exposure in an underwater in-vitro ureter model. For comparison, temperatures with and without irrigation and with different distances from the laser fiber to the thermometer are measured. Materials and Methods: We used the Ho:YAG-laser (Vera PulseTM, Coherent) with a 365 μm laser fiber. The settings of the laser were 0.6 J with a frequency of 5 Hz which is the minimum setting for that type of laser. The experimental setup was closely aligned with the clinical situation. A metal container was filled with 0.9% sodium chloride (NaCl) solution (Temp. 36.8°) and a catheter with an inner diameter of 4 mm was attached to the rim of the container. The tip of the thermometer was attached inside the catheter through a waterproof hole. The laser fiber was guided by means of a rigid URS video device (11.5 F). We had four different settings during the measurement: 1) Distance of 0.5 cm between the laser and the thermometer;without irrigation, 2) Distance of 0.5 cm between the laser and the thermometer;with irrigation, 3) Distance of 1 cm between the laser and the thermometer;without irrigation, 4) Distance of 1 cm between the laser and the thermometer;with irrigation. Results: The maximum overall temperature was recorded in the 1) and 3) setting, both featuring no irrigation. The maximum temperature was ~50°C in both settings, with the 1) setting reaching the maximum temperature after 50 seconds and hence approximately twice as fast as the 3) setting. During measurements with a NaCl solution flow we couldn’t detect any noticeable increase in temperature, neither at short nor at long distance between the laser fiber and the thermometer. Conclusion: There is a relevant heating in the ureter beside an endourologic lithotripsy. In our model we could reproduce a maximum heating unt
基金the National Basic Research Program of China(Grant No.2013CBA01604)the National Science and Technology Major Project of China(Grant No.2011ZX02707)
文摘Poly(methyl methacrylate)(PMMA) is widely used for graphene transfer and device fabrication.However,it inevitably leaves a thin layer of polymer residues after acetone rinsing and leads to dramatic degradation of device performance.How to eliminate contamination and restore clean surfaces of graphene is still highly demanded.In this paper,we present a reliable and position-controllable method to remove the polymer residues on graphene films by laser exposure.Under proper laser conditions,PMMA residues can be substantially reduced without introducing defects to the underlying graphene.Furthermore,by applying this laser cleaning technique to the channel and contacts of graphene fieldeffect transistors(GFETs),higher carrier mobility as well as lower contact resistance can be realized.This work opens a way for probing intrinsic properties of contaminant-free graphene and fabricating high-performance GFETs with both clean channel and intimate graphene/metal contact.
基金Project(2010CB731705)supported by the National Basic Research Program of China
文摘Cyclic thermal exposure tests of infrared heating to 800 ℃ in 120 s followed by compressed air cooling to 150 ℃ in 60 s were performed for the laser deposited Ti60A （Ti5.54Al3.38Sn3.34Zr0.37Mo0.46Si） alloy. The effects of thermal exposure cycles on length ofβphase, area fraction ofαphase and microhardness of alloy were examined by OM, SEM and EDS. The results indicate that thermal exposure cycles have significant effects on length ofβphase, area fraction ofαphase and microhardness of the alloy. The original fine basket-weaveβand 78.5%αtransform to transient wedge-likeβ, finally leaving granularβand 97.6%coarsenedαwith the increased thermal exposure cycles. The formation mechanism of coarsenedαand broken-upβmicrostructure is discussed. The alloy after 750 thermal exposure cycles has the maximum microhardness, 33.3%higher than that of the as-deposited alloy.
基金supported by the Materials and Energy Research Center (MERC),Nanotechnology and Advanced Materials Department in the framework of Project Number 728811
文摘Experimental work has been focused on the formation of alloyed Au-Cu nanoparticles under simultaneous laser exposure and mechanical stirring of mixed monometallic colloids, here referred to as dual procedure. As a feed for the dual procedure, Au and Cu monometallic nanoparticle colloids have been using a laser ablation technique. To accomplish this, bulk targets were ablated with 1064 nm wavelength Nd: YAG laser in a pure acetone(99.99%) environment. Ultraviolet-visible optical absorption spectrometry, transmission electron microscopy, X-ray diffraction and X-ray fluorescence technique have been used to characterize the nanoparticles. It has been found that experimental conditions such as stirring and laser parameters strongly affect the synthesized particle properties, including the size, shape, composition and stability of the nanoparticles. Alloy nanoparticles containing 39% Au – 61% Cu have also been prepared in the same process, but in two forms of a homogeneous alloy and a core-shell structure.
文摘Plasma X-ray sources for biological microscopy have been produced by focusing single shots from Nd:glass laser onto carbon rod targets at irradiances between 1 × 1013 W⋅cm−2 and 3 × 1013 W⋅cm−2 to expose test objects. The optimum parameters needed for obtaining high accurate information on the samples under test namely: the minimum energies and irradiances at a range of angles between the incoming laser beam and the normal to the resist, the depth of exposure of the photoresist as a function of incident laser energy (and irradiance) were concluded in this work.
