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RSS2003 Vol. 27, No. 6
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2003, 27(6): 497-499.
[Abstract]
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Abstract:
Based on the principle of probe beam deflection,the ablation thresholds of three copper samples with different roughness are measured in moist and dry environment.The results show that,in the two kinds of environment,the larger the roughness,the lower the ablation threshold.When the roughness and the pump energy fluence are all equal,the ablation threshold is lower in the moist environment than in the dry environment.This phenomenon indicates that the rough and moist surface has big absorption coefficient to pump energy,which can be proved by the different transit time in the case of the same pump energy fluence.
Based on the principle of probe beam deflection,the ablation thresholds of three copper samples with different roughness are measured in moist and dry environment.The results show that,in the two kinds of environment,the larger the roughness,the lower the ablation threshold.When the roughness and the pump energy fluence are all equal,the ablation threshold is lower in the moist environment than in the dry environment.This phenomenon indicates that the rough and moist surface has big absorption coefficient to pump energy,which can be proved by the different transit time in the case of the same pump energy fluence.
2003, 27(6): 500-502,509.
Abstract:
The laser surface hardening for mould-cutting roller of 50 carbon steel is carried out using continuous wave CO2 laser beam.The microstructure observation and hardness distribution testing in the cross-section of the hardened layer are performed.The results indicate that the microstructure of the hardened layer of mould-cutting roller quenched consists of the fine dislocated lath martensite and a small quantity of residual austenite.After laser surface hardening,the mould-cutting roller possesses of small contraction distortion,high hardness,and uniform distribution of hardness.And hence using laser surface hardening process to modify the surface of mould-cutting roller of 50 carbon steel is practicable.
The laser surface hardening for mould-cutting roller of 50 carbon steel is carried out using continuous wave CO2 laser beam.The microstructure observation and hardness distribution testing in the cross-section of the hardened layer are performed.The results indicate that the microstructure of the hardened layer of mould-cutting roller quenched consists of the fine dislocated lath martensite and a small quantity of residual austenite.After laser surface hardening,the mould-cutting roller possesses of small contraction distortion,high hardness,and uniform distribution of hardness.And hence using laser surface hardening process to modify the surface of mould-cutting roller of 50 carbon steel is practicable.
2003, 27(6): 503-505.
Abstract:
Welding porosity is the main defect during laser welding.In this paper we briefly analyze the mechanism of engendering pores in powder metal material(PM),and study the influence of welding speed and active gas for welding porosity defect.We find that the pore number will be reduced through depressing metallic vapour if welding speed is increased with constant laser power.Using N2,O2 as active gas,the fluidity of the melting metal can be improved,so blowholes may be avoided.
Welding porosity is the main defect during laser welding.In this paper we briefly analyze the mechanism of engendering pores in powder metal material(PM),and study the influence of welding speed and active gas for welding porosity defect.We find that the pore number will be reduced through depressing metallic vapour if welding speed is increased with constant laser power.Using N2,O2 as active gas,the fluidity of the melting metal can be improved,so blowholes may be avoided.
2003, 27(6): 510-513.
Abstract:
The mechanism of action of excimer laser (ArF:193nm 8ns) on cornea is very important in the ablation refractive surgeries such as laser in situ keratomileusis(LASIK)and photorefractive keratectomy(PRK).In this paper,we analyze photoablation model and photophysical model that describe the mechanism of action of excimer laser (ArF:193nm 8ns) on cornea,elicit the relationship between the energy density and the ablation depth.The factors that would influence the predictability and stability of the photorefractive surgery outcome are also investigated.Then the scanning algorithm can be optimized.The results have been directly applied to the ophthalmic excimer laser system and obtain satisfactory effect in diopter correction.
The mechanism of action of excimer laser (ArF:193nm 8ns) on cornea is very important in the ablation refractive surgeries such as laser in situ keratomileusis(LASIK)and photorefractive keratectomy(PRK).In this paper,we analyze photoablation model and photophysical model that describe the mechanism of action of excimer laser (ArF:193nm 8ns) on cornea,elicit the relationship between the energy density and the ablation depth.The factors that would influence the predictability and stability of the photorefractive surgery outcome are also investigated.Then the scanning algorithm can be optimized.The results have been directly applied to the ophthalmic excimer laser system and obtain satisfactory effect in diopter correction.
2003, 27(6): 514-516,596.
Abstract:
A four-dimension simulation code is developed,which enables us to study the thermal effect of high-power lasers propagating through a beam control system.As illustrated examples,the thermal effects of high-power lasers with initial Gaussian and flat-topped profiles in passage through the beam control system on the beam quality in the far field characterized by the Strehl ratio,the focussiablity(i.e.,radius of the encircled 86.5% power),astigmatism parameter and shift of the beam gravity are studied.It is shown that the beam quality in the far field depends on the initial field distribution,and is degraded with increasing emissive power.
A four-dimension simulation code is developed,which enables us to study the thermal effect of high-power lasers propagating through a beam control system.As illustrated examples,the thermal effects of high-power lasers with initial Gaussian and flat-topped profiles in passage through the beam control system on the beam quality in the far field characterized by the Strehl ratio,the focussiablity(i.e.,radius of the encircled 86.5% power),astigmatism parameter and shift of the beam gravity are studied.It is shown that the beam quality in the far field depends on the initial field distribution,and is degraded with increasing emissive power.
2003, 27(6): 517-519.
Abstract:
A vector algorithm for designing two dimensions,finite aperture,aperiodic diffractive optical elements based on rigorous electromagnetic computation model the finite-difference time-domain method has been proposed.All aspects relating to the algorithm such as optimization process,the finite-difference time-domain method,and the diffractive integral,have been discussed.The algorithm can present rigorous design results with reasonable computational cost and good designing results.Two double off-axis diffractive lenses for normally incident TE mode have been designed to illustrate the algorithm.The algorithm is useful for the improvement of vector algorithm for designing diffractive optical elements and the applications of diffractive optical elements.
A vector algorithm for designing two dimensions,finite aperture,aperiodic diffractive optical elements based on rigorous electromagnetic computation model the finite-difference time-domain method has been proposed.All aspects relating to the algorithm such as optimization process,the finite-difference time-domain method,and the diffractive integral,have been discussed.The algorithm can present rigorous design results with reasonable computational cost and good designing results.Two double off-axis diffractive lenses for normally incident TE mode have been designed to illustrate the algorithm.The algorithm is useful for the improvement of vector algorithm for designing diffractive optical elements and the applications of diffractive optical elements.
2003, 27(6): 520-522,530.
Abstract:
The equivalent area method and inscribed circle method are put forward based on the ellipse method of arbitrary particles for expressing their sizes,the expressions of their shape-affecter and solution of them are studied upon above methods.We think the inscribed circle method as a good expressing for arbitrary particles' size after compared them with each other in their dynamical character.Then,a good gist is established to measure the function of particles' character in theory through the shape-affecter drafting.
The equivalent area method and inscribed circle method are put forward based on the ellipse method of arbitrary particles for expressing their sizes,the expressions of their shape-affecter and solution of them are studied upon above methods.We think the inscribed circle method as a good expressing for arbitrary particles' size after compared them with each other in their dynamical character.Then,a good gist is established to measure the function of particles' character in theory through the shape-affecter drafting.
2003, 27(6): 523-525.
Abstract:
In this paper,the pump coupling and laser feedback in high power double cladding fiber lasers are analyzed,and some ways that should be taken to enhance the capability are also pointed.Conclusions can be drawn that the best scheme is to use side-pump with tapered fiber bundle and fiber grating as the reflector of laser.The potential of Fresnel zone plate used as the coupling device is given.In order to avoid the destruction of plane dichromatic mirror used as the laser reflector,dichromatic spherical lens with the same thickness used as the feedback of laser is proposed in optical fiber laser design for the first time.
In this paper,the pump coupling and laser feedback in high power double cladding fiber lasers are analyzed,and some ways that should be taken to enhance the capability are also pointed.Conclusions can be drawn that the best scheme is to use side-pump with tapered fiber bundle and fiber grating as the reflector of laser.The potential of Fresnel zone plate used as the coupling device is given.In order to avoid the destruction of plane dichromatic mirror used as the laser reflector,dichromatic spherical lens with the same thickness used as the feedback of laser is proposed in optical fiber laser design for the first time.
2003, 27(6): 526-530.
Abstract:
The spontaneous parametric down-conversion (SPDC) light field is generated by the combined action of a monochromatic flux of pumping photons and quantum vacuum noise on a nonlinear crystal with no center of symmetry.Its intrinsical quantum origin determines its important role in the area of non-classical field research.In this paper,the coherence characteristics of the SPDC light field is investigated theoretically,and the application of SPDC light field to absolute measurement of quantum efficiency of photo detectors is studied experimentally.Finally,it points out the wide application prospect of SPDC light field application.
The spontaneous parametric down-conversion (SPDC) light field is generated by the combined action of a monochromatic flux of pumping photons and quantum vacuum noise on a nonlinear crystal with no center of symmetry.Its intrinsical quantum origin determines its important role in the area of non-classical field research.In this paper,the coherence characteristics of the SPDC light field is investigated theoretically,and the application of SPDC light field to absolute measurement of quantum efficiency of photo detectors is studied experimentally.Finally,it points out the wide application prospect of SPDC light field application.
2003, 27(6): 531-533,537.
Abstract:
Studies have been made on the influences of the second order derivatives of the amplitude and phase of the reflection coefficient on the Gaussian pulse upon reflection from the dielectric mirrors.Results show that the amplitude characteristics of the reflection may also be used to compress the pulse.Specifically,mirrors with a minimum reflectivity at the central frequency can be used to reduce the widths of less chirped pulses and those with a maximum reflectivity can compress pulses of larger chirping factors.
Studies have been made on the influences of the second order derivatives of the amplitude and phase of the reflection coefficient on the Gaussian pulse upon reflection from the dielectric mirrors.Results show that the amplitude characteristics of the reflection may also be used to compress the pulse.Specifically,mirrors with a minimum reflectivity at the central frequency can be used to reduce the widths of less chirped pulses and those with a maximum reflectivity can compress pulses of larger chirping factors.
2003, 27(6): 534-537.
Abstract:
Under stable-cavity-condition,expression of thermal focal length is educed in the view of cavity.Thermal focal length of Nd:YVO4 crystal is measured,and the result is obtained in experiment.We calculate it in its traditional formula too.At last the two results is compared,and we make a conclusion that they are coincident basically.
Under stable-cavity-condition,expression of thermal focal length is educed in the view of cavity.Thermal focal length of Nd:YVO4 crystal is measured,and the result is obtained in experiment.We calculate it in its traditional formula too.At last the two results is compared,and we make a conclusion that they are coincident basically.
2003, 27(6): 538-540,562.
Abstract:
Analyses of the mechanisms of acetic acid emitting fluorescence and fluorescence quenching have been made in theory.The results indicate that acetic acid solutions can emit visible fluorescence when induced by 253.7nm UV light,and fluorescence quenching occurs along with the alteration of solution concentration.It is thought that fluorescence dynamic quenching process could take into account the intersystem transition of (n,π *) to (π,π *),and the quenching constant is calculated in this paper.Investigation on the native fluorescence spectrum and its characteristics will contribute to the study of other molecules fluorescence spectra when acetic acid serves as solute,hydrolysis catalyst and food additive.
Analyses of the mechanisms of acetic acid emitting fluorescence and fluorescence quenching have been made in theory.The results indicate that acetic acid solutions can emit visible fluorescence when induced by 253.7nm UV light,and fluorescence quenching occurs along with the alteration of solution concentration.It is thought that fluorescence dynamic quenching process could take into account the intersystem transition of (n,π *) to (π,π *),and the quenching constant is calculated in this paper.Investigation on the native fluorescence spectrum and its characteristics will contribute to the study of other molecules fluorescence spectra when acetic acid serves as solute,hydrolysis catalyst and food additive.
2003, 27(6): 541-543,576.
Abstract:
Numerical simulation has been carried out to study the evolution of perturbed laser beam after passing through a piece of nonlinear medium.The variation of "hot image"with incident beam energy,modulation depth and modulation width have been studied.It has been concluded that:in some conditions,there can be a "hot image" at the ordinarily called "conjugated plane",but in other conditions,peak fluency density is very high at some places other than "conjugated plane".Phase modulation depth can deeply influence the evolution of the laser beam,and some kind of depth may induce more serious damage than others.In addition,modulation width and incident beam energy will also influence the distribution of the field.
Numerical simulation has been carried out to study the evolution of perturbed laser beam after passing through a piece of nonlinear medium.The variation of "hot image"with incident beam energy,modulation depth and modulation width have been studied.It has been concluded that:in some conditions,there can be a "hot image" at the ordinarily called "conjugated plane",but in other conditions,peak fluency density is very high at some places other than "conjugated plane".Phase modulation depth can deeply influence the evolution of the laser beam,and some kind of depth may induce more serious damage than others.In addition,modulation width and incident beam energy will also influence the distribution of the field.
2003, 27(6): 544-546,550.
Abstract:
The effects of He-Ne laser on vigor of α-amylase,GPT,GOT and content of soluble protein and soluble sacchrides of isatis indigotica have been studied.The results indicate:four treatments have improved the vigor of α-amylase,GPT and GOT.Moreover,7min treatment is the best for α-amylase,and 5min treatment is the best for GPT and GOT.Four treatments have improved apparently content,protein content and soluble sacchrides of isatis indigotica,5min treatment is the best among four treatments.
The effects of He-Ne laser on vigor of α-amylase,GPT,GOT and content of soluble protein and soluble sacchrides of isatis indigotica have been studied.The results indicate:four treatments have improved the vigor of α-amylase,GPT and GOT.Moreover,7min treatment is the best for α-amylase,and 5min treatment is the best for GPT and GOT.Four treatments have improved apparently content,protein content and soluble sacchrides of isatis indigotica,5min treatment is the best among four treatments.
2003, 27(6): 547-550.
Abstract:
In this paper,two rapidly tuning techniques which include a six surface mirrors scanning a fixed grating and a high frequency stepping motor controlling a diffraction grating are presented.It is illustrated in experiments that the means of stepping motor is better than that of rotating mirror.Laser operated at 51 emission lines is obtained,and the pulse energy of laser radiation at first order is about (30～100)mJ.The system can be tuned rapidly different rotational lines with a single laser,the tuning time interval to different lines is not large than 10ms.
In this paper,two rapidly tuning techniques which include a six surface mirrors scanning a fixed grating and a high frequency stepping motor controlling a diffraction grating are presented.It is illustrated in experiments that the means of stepping motor is better than that of rotating mirror.Laser operated at 51 emission lines is obtained,and the pulse energy of laser radiation at first order is about (30～100)mJ.The system can be tuned rapidly different rotational lines with a single laser,the tuning time interval to different lines is not large than 10ms.
2003, 27(6): 551-553,566.
Abstract:
Recent advances of diode-pumped thin disc-laser are reviewed.The power-scalable experiment schemes and related results are analyzed.Some problems for practical applications are discussed too.
Recent advances of diode-pumped thin disc-laser are reviewed.The power-scalable experiment schemes and related results are analyzed.Some problems for practical applications are discussed too.
2003, 27(6): 554-556.
Abstract:
In order to research into the optical damage in iron-doped lithium niobate crystals,we investigated the decay behavior of the optical damage in iron-doped lithium niobate crystals.The dark decay time of the optical damage in thin crystal sheets was found to far exceed that in the thick crystal sheets.The OH-spectra and Raman spectra were performed in order to clarify the underlying mechanism.In conclusion,the thickness of samples greatly influences the optical damage.
In order to research into the optical damage in iron-doped lithium niobate crystals,we investigated the decay behavior of the optical damage in iron-doped lithium niobate crystals.The dark decay time of the optical damage in thin crystal sheets was found to far exceed that in the thick crystal sheets.The OH-spectra and Raman spectra were performed in order to clarify the underlying mechanism.In conclusion,the thickness of samples greatly influences the optical damage.
2003, 27(6): 557-559.
Abstract:
A new laser ultrasonic sensor for testing samples' thickness is developed.The detection principle is discussed in detail.This sensor has high-frequency response,high sensitivity and is easy to adjust.The sensor is used to detect laser-induced ultrasonic longitude-wave at the epicenter of the rear metallic surface when pulse Nd:YAG laser is focused on polished iron plate.Well-defined longitude-wave and its echo waves are acquired.Based on the experimental results,the sample's thickness can be deduced.The theoretical and experimental results are in good agreement with relative error of 0.5%.
A new laser ultrasonic sensor for testing samples' thickness is developed.The detection principle is discussed in detail.This sensor has high-frequency response,high sensitivity and is easy to adjust.The sensor is used to detect laser-induced ultrasonic longitude-wave at the epicenter of the rear metallic surface when pulse Nd:YAG laser is focused on polished iron plate.Well-defined longitude-wave and its echo waves are acquired.Based on the experimental results,the sample's thickness can be deduced.The theoretical and experimental results are in good agreement with relative error of 0.5%.
2003, 27(6): 560-562.
Abstract:
In this paper,the splitting angle and the light intensity splitting ratio of o ray and e ray changing with incident angle are analyzed after non-polarized light penetrates the OE double escape prism.The result proves that the splitting angle changes 2α when the incident angle changes α.At the same time,the intensity splitting ratio doesn't remain 1:1,but presents to be a nonlinear relation.
In this paper,the splitting angle and the light intensity splitting ratio of o ray and e ray changing with incident angle are analyzed after non-polarized light penetrates the OE double escape prism.The result proves that the splitting angle changes 2α when the incident angle changes α.At the same time,the intensity splitting ratio doesn't remain 1:1,but presents to be a nonlinear relation.
2003, 27(6): 563-566.
Abstract:
In this paper,a new dynamic and high speed laser drilling system equipped on product line is presented,which is especially fit for thin material's drilling.Moreover some related key technology such as dynamic track,method of distinguishing direction and distortion correction for dual galvanometer scanning has been discussed.
In this paper,a new dynamic and high speed laser drilling system equipped on product line is presented,which is especially fit for thin material's drilling.Moreover some related key technology such as dynamic track,method of distinguishing direction and distortion correction for dual galvanometer scanning has been discussed.
2003, 27(6): 567-568,571.
Abstract:
The architecture and function for the archibald firing training system are introduced in this paper.The circuit design and principle of laser transmitter and receiver are described in detail.Simulation training in all weather for the archibald firing is implemented.In addition,functions of natural and fair evaluation for the artilleryman firing are obtained.
The architecture and function for the archibald firing training system are introduced in this paper.The circuit design and principle of laser transmitter and receiver are described in detail.Simulation training in all weather for the archibald firing is implemented.In addition,functions of natural and fair evaluation for the artilleryman firing are obtained.
2003, 27(6): 569-571.
Abstract:
This paper introduces a high precision high-voltage feedback control circuit.The transmitting circuit turns the real-time voltage into serial digital signals to modulate the light of the semiconductor laser.After passing the high-voltage insulating barrier,the light is received by receiving circuit.Through photodiode and 74AHC inverter,the serial digital signals are obtained and sent to the microcontroller to form a closed-loop control.
This paper introduces a high precision high-voltage feedback control circuit.The transmitting circuit turns the real-time voltage into serial digital signals to modulate the light of the semiconductor laser.After passing the high-voltage insulating barrier,the light is received by receiving circuit.Through photodiode and 74AHC inverter,the serial digital signals are obtained and sent to the microcontroller to form a closed-loop control.
Discussion on direct manufacturing metallic pattern for sand mold based on laser cladding technology
2003, 27(6): 572-576.
Abstract:
This paper discusses laser direct manufacturing metallic patterns for sand mould based on laser cladding technology.The fundamental principle and characteristics of this rapid manufacturing (RM) technology are introduced.According to analysis of the structure and working condition of metallic pattern for sand mould,it is demonstrated that this RM technology would make great contributions to fabrication of this pattern.In practice,to acquire lightweight products and to decrease consumption in the procedure,corresponding measures are put forward to improve the process of laser cladding.Finally,it is indicated that lightweight patterns would be produced in low-consumption procedures while the relative techniques and their integration being advanced enough.
This paper discusses laser direct manufacturing metallic patterns for sand mould based on laser cladding technology.The fundamental principle and characteristics of this rapid manufacturing (RM) technology are introduced.According to analysis of the structure and working condition of metallic pattern for sand mould,it is demonstrated that this RM technology would make great contributions to fabrication of this pattern.In practice,to acquire lightweight products and to decrease consumption in the procedure,corresponding measures are put forward to improve the process of laser cladding.Finally,it is indicated that lightweight patterns would be produced in low-consumption procedures while the relative techniques and their integration being advanced enough.
2003, 27(6): 577-579.
Abstract:
The interaction of solitons and Gaussian quasi-solitons in propagation is studied by solving the NLS equation.The results of the propagation depend on not only the types of soliton but also the transmitting ways.In a special way of propagation the problem of signal interaction can be solved.
The interaction of solitons and Gaussian quasi-solitons in propagation is studied by solving the NLS equation.The results of the propagation depend on not only the types of soliton but also the transmitting ways.In a special way of propagation the problem of signal interaction can be solved.
2003, 27(6): 580-583,587.
Abstract:
Based on the laser beam classification in accordance with the spatial symmetry and spatial coherence,the parametric characterization of laser beams is studied.The anisotropic twisted Gaussion-Schell model (ATGSM) beam,isotropic twisted Gaussian-Schell model (ITGSM) beam,anisotropic Gaussian-Schell model (AGSM) beam,rotated astigmatic Gaussian-Schell model (RAGSM) beam,aligned astigmatic Gaussian-Schell model (AAGSM) beam,stigmatic Gaussian-Schell model (SGSM) beam,general astigmatic Gaussian (GAG) beam,rotated astigmatic Gaussian (RAG) beam,aligned astigmatic Gaussian (AAG) beam,and stigmatic Gaussian (SG) beam are taken as typical illustrative examples,their classification and the number of independent beam parameters are analyzed.Some related problems are also discussed.
Based on the laser beam classification in accordance with the spatial symmetry and spatial coherence,the parametric characterization of laser beams is studied.The anisotropic twisted Gaussion-Schell model (ATGSM) beam,isotropic twisted Gaussian-Schell model (ITGSM) beam,anisotropic Gaussian-Schell model (AGSM) beam,rotated astigmatic Gaussian-Schell model (RAGSM) beam,aligned astigmatic Gaussian-Schell model (AAGSM) beam,stigmatic Gaussian-Schell model (SGSM) beam,general astigmatic Gaussian (GAG) beam,rotated astigmatic Gaussian (RAG) beam,aligned astigmatic Gaussian (AAG) beam,and stigmatic Gaussian (SG) beam are taken as typical illustrative examples,their classification and the number of independent beam parameters are analyzed.Some related problems are also discussed.
2003, 27(6): 584-587.
Abstract:
An algorithm for laser stripe matching based on the epipolar constraint is presented.First,the left and right image are taken by CCD camera,then the two images are pre-processed.After being processed the two images that are taken at different angle of view are two pieces of laser stripe of single pixel.A method to solve the point of curve and line matching is proposed based on epipolar and continuity constraint,which ensures that fast precise matching of laser stripe and 3D reconstruction of laser scanning line can be realized.
An algorithm for laser stripe matching based on the epipolar constraint is presented.First,the left and right image are taken by CCD camera,then the two images are pre-processed.After being processed the two images that are taken at different angle of view are two pieces of laser stripe of single pixel.A method to solve the point of curve and line matching is proposed based on epipolar and continuity constraint,which ensures that fast precise matching of laser stripe and 3D reconstruction of laser scanning line can be realized.
2003, 27(6): 588-590.
Abstract:
Power is a basic parameter of the laser.Its' stabilization and accuracy will directly influence laser process and many other fields.The power detection and control system for high power CO2 laser samples the laser power by the transmission light of the high reflective mirror.Furthermore,it can detect and monitor the laser power of the whole system by a S7-200 PLC.It greatly enhances the stabilization and accuracy of the control,and has no influence on the output.
Power is a basic parameter of the laser.Its' stabilization and accuracy will directly influence laser process and many other fields.The power detection and control system for high power CO2 laser samples the laser power by the transmission light of the high reflective mirror.Furthermore,it can detect and monitor the laser power of the whole system by a S7-200 PLC.It greatly enhances the stabilization and accuracy of the control,and has no influence on the output.
2003, 27(6): 591-593.
Abstract:
The effect on neural functional recovery irradiated by magnetized low intensity semiconductor laser is studied.The rabbits were divided into 3week,6week,9week,12week groups according to the observation period.The magnetized laser irradiated group,the laser irradiated group and the control group were used in each observation period.Irradiated the rabbits with injury of common personeal nerve in the laser irradiated group and the magnetized laser group,for 5min once a day,in 7 days.The regeneration of the axon,the latent rate of the common personeal nerve,the toe expansion test were all observed systematically in the groups.A few thin-regenerated axon were seen at 3rd week in the irradiated groups.The magnetized laser irradiated group was better than the laser irradiated group.The latent rate of the common personeal nerve was the magnetized laser irradiated groups than in control and the laser group.The amplitude of the irradiated groups was higher than in control.12 weeks postoperatively,the toe extension test was normal in the magnetized laser irradiated group,while among the laser irradiated group it was the same as seen at 9th week after operation in the magnetized laser irradiated group,and it was the same as seen at 6th week after operation among the control group.Magnetized low intensity semiconductor laser could promote the function of the spine motor nerve cells and accelerate the axonal regeneration.
The effect on neural functional recovery irradiated by magnetized low intensity semiconductor laser is studied.The rabbits were divided into 3week,6week,9week,12week groups according to the observation period.The magnetized laser irradiated group,the laser irradiated group and the control group were used in each observation period.Irradiated the rabbits with injury of common personeal nerve in the laser irradiated group and the magnetized laser group,for 5min once a day,in 7 days.The regeneration of the axon,the latent rate of the common personeal nerve,the toe expansion test were all observed systematically in the groups.A few thin-regenerated axon were seen at 3rd week in the irradiated groups.The magnetized laser irradiated group was better than the laser irradiated group.The latent rate of the common personeal nerve was the magnetized laser irradiated groups than in control and the laser group.The amplitude of the irradiated groups was higher than in control.12 weeks postoperatively,the toe extension test was normal in the magnetized laser irradiated group,while among the laser irradiated group it was the same as seen at 9th week after operation in the magnetized laser irradiated group,and it was the same as seen at 6th week after operation among the control group.Magnetized low intensity semiconductor laser could promote the function of the spine motor nerve cells and accelerate the axonal regeneration.
2003, 27(6): 594-596.
Abstract:
The position sensitive detector(PSD) is an photo-electronic sensor which can detect the continuous position of a light spot traveling over its surface,and convert the position of light spot to simple electric current signal.Based upon PSD,many types of precision and contactless motion detection instruments could be constructed.The most important problem to use the PSD is how to overcome the influence of non-linear action on the PSD.Therefore to improve the precision and reliablity of the instrument.Based on artificial neural network,a non-linear compensation method of PSD is presented in this paper.In order to non-linear compensation over a full range,the neural network is trained to represent the non-linear mapping between sensor reading and their represent output accurately properly.It is revealed from the computer simulation result that not only the influence of non-linear fluctuation can be eliminated effectively,but also a desired linear relationship between the sensor input and the neural network output can be obtained.
The position sensitive detector(PSD) is an photo-electronic sensor which can detect the continuous position of a light spot traveling over its surface,and convert the position of light spot to simple electric current signal.Based upon PSD,many types of precision and contactless motion detection instruments could be constructed.The most important problem to use the PSD is how to overcome the influence of non-linear action on the PSD.Therefore to improve the precision and reliablity of the instrument.Based on artificial neural network,a non-linear compensation method of PSD is presented in this paper.In order to non-linear compensation over a full range,the neural network is trained to represent the non-linear mapping between sensor reading and their represent output accurately properly.It is revealed from the computer simulation result that not only the influence of non-linear fluctuation can be eliminated effectively,but also a desired linear relationship between the sensor input and the neural network output can be obtained.
2003, 27(6): 597-599.
Abstract:
Phenomenon of transmitted light intensity's perturbance of the Glan-Taylor prism with varying rotation angle is found in the experiment.It has notable influence on quality of the outgoing polarized light.Causes for the disturbance are analysed.Several parameters that affect the smoothness level of curve of transmitted light intensity are discussed.And the effective methods to reduce the disturbance are obtained.
Phenomenon of transmitted light intensity's perturbance of the Glan-Taylor prism with varying rotation angle is found in the experiment.It has notable influence on quality of the outgoing polarized light.Causes for the disturbance are analysed.Several parameters that affect the smoothness level of curve of transmitted light intensity are discussed.And the effective methods to reduce the disturbance are obtained.
2003, 27(6): 600-602.
Abstract:
The reflective characteristics of the diffused targets are analyzed in the applied fields of the laser technology.The "cat's eye" effect of optical lens,being focused in recent years,is discussed in detail.Test results are given and its applications are introduced briefly.
The reflective characteristics of the diffused targets are analyzed in the applied fields of the laser technology.The "cat's eye" effect of optical lens,being focused in recent years,is discussed in detail.Test results are given and its applications are introduced briefly.
2003, 27(6): 603-605.
Abstract:
Range gating is a kind of effective method which can eliminate backscattered light and increase the SNR of the laser range gated (LRG) imaging system.The theory of range gating is described,and the key techniques for range gating are analyzed briefly.Then the shortcomings of the traditional range-gated synchronization control system are pointed out.Finally kind of improved scheme for range-gated synchronization control is proposed.
Range gating is a kind of effective method which can eliminate backscattered light and increase the SNR of the laser range gated (LRG) imaging system.The theory of range gating is described,and the key techniques for range gating are analyzed briefly.Then the shortcomings of the traditional range-gated synchronization control system are pointed out.Finally kind of improved scheme for range-gated synchronization control is proposed.
2003, 27(6): 606-608.
Abstract:
The experiment is conducted by using an Er3+/Yb3+ co-doped double clad fiber with 2m long fiber and input power of 1W.The output power of 242mW with wavelength of 1563.596nm are obtained.
The experiment is conducted by using an Er3+/Yb3+ co-doped double clad fiber with 2m long fiber and input power of 1W.The output power of 242mW with wavelength of 1563.596nm are obtained.
2003, 27(6): 506-509.
Abstract:
How laser pretreatment can improve soybean seedlings' cold acclimation is studied in the view of energy transformation,biomembrane integrality and oxygen free radical injury.The results show that pretreatment of soybean seeds with He-Ne laser enhance not only the seeds' content of ATP but also seedlings' cold acclimation during cotyledons to primary leaves stage.Pretreatment groups' seedlings at 3℃～5℃ temperature have much higher enzyme activities and content of catalase(CAT),peroxidase(POD),superoxide dismutase(SOD),amylase(AML) and soluble protein content than those in control.Pretreatment of soybean seeds with laser also decreases the rate of product of O2-,the accumulation of MDA and the conductivity rate at low temperature.
How laser pretreatment can improve soybean seedlings' cold acclimation is studied in the view of energy transformation,biomembrane integrality and oxygen free radical injury.The results show that pretreatment of soybean seeds with He-Ne laser enhance not only the seeds' content of ATP but also seedlings' cold acclimation during cotyledons to primary leaves stage.Pretreatment groups' seedlings at 3℃～5℃ temperature have much higher enzyme activities and content of catalase(CAT),peroxidase(POD),superoxide dismutase(SOD),amylase(AML) and soluble protein content than those in control.Pretreatment of soybean seeds with laser also decreases the rate of product of O2-,the accumulation of MDA and the conductivity rate at low temperature.
