This paper describes the development of a timer based voltage to frequency converter(V FC).Timer LM555is used in astable multivibrator mode with two OPTO-LDRs(light dependent resistors)in the circuitry.The frequency o...This paper describes the development of a timer based voltage to frequency converter(V FC).Timer LM555is used in astable multivibrator mode with two OPTO-LDRs(light dependent resistors)in the circuitry.The frequency of timer output waveform which is measured using a digital storage oscillator(DSO)is almost linearly proportional to the applied input voltage.Hence we obtain a linear relationship between the frequency of timer output waveform and the input voltage.Because of its quasi-digital output,the main advantages of this developed converter are linear input-output relationship,small size,easy portabilityand high cost performance.In addition,the timer output waveform can be directly interfaced with personal computer or microprocessor/microcontroller for further processing of the input voltage signal without intervening any analog-to-digital converter(ADC).展开更多
The ultrafast photoinduced strain(UPS)resulting from the coupling of piezoelectric and photovoltaic effects in ferroelectric has been focused in the last decade,endowing them with extensive applications including ultr...The ultrafast photoinduced strain(UPS)resulting from the coupling of piezoelectric and photovoltaic effects in ferroelectric has been focused in the last decade,endowing them with extensive applications including ultrafast optical memories,sensors and actuators with strain engineering.The mechanism of screening of the depolarization field by photoinduced carriers is generally accepted for UPS in ferroelectrics,while the thermal component of the strain is usually diluted as the offset and has not been systematically confronted,leading to unnecessary confusion.Herein,both the positive and negative thermal expansion effects in composite ferroelectric epitaxial films are investigated by use of high-repetition-rate ultrafast X-ray diffraction,along with the piezoelectric and photovoltaic effects.The coupling of the positive/negative thermal effects and the piezoelectric/photovoltaic effects in ultrafast strain is evidenced and can be regulated.The opposite lattice responses due to different thermal effects of the samples with different axial ratios are observed.The maximum UPS is up to 0.24%,comparable to that of conventional ferroelectric.The interaction between the thermal and ferroelectric effects in the induced strain could promote the diversified applications with the coupling of light,heat and electricity.展开更多
文摘This paper describes the development of a timer based voltage to frequency converter(V FC).Timer LM555is used in astable multivibrator mode with two OPTO-LDRs(light dependent resistors)in the circuitry.The frequency of timer output waveform which is measured using a digital storage oscillator(DSO)is almost linearly proportional to the applied input voltage.Hence we obtain a linear relationship between the frequency of timer output waveform and the input voltage.Because of its quasi-digital output,the main advantages of this developed converter are linear input-output relationship,small size,easy portabilityand high cost performance.In addition,the timer output waveform can be directly interfaced with personal computer or microprocessor/microcontroller for further processing of the input voltage signal without intervening any analog-to-digital converter(ADC).
文摘The liquid crystal television spatial light modulator (LCTVSLM) characterized is usable in optical processing applications,e.g.,optical pattern recognition,associative memory, optical computing,correlation detection and optical data processing systems.The array performance and real-time optical correlation applications are reviewed.
基金supported by the National Key Research and Development Program of China(2018YFA0703700 and 2017YFE0119700)the National Natural Science Foundation of China(21801013,1190524,51774034 and 51961135107)+2 种基金Beijing Natural Science Foundation(2182039)the Fundamental Research Funds for the Central Universities(FRF-IDRY-19-007 and FRF-TP-19-055A2Z)the Young Elite Scientists Sponsorship Program by CAST(20192021QNRC)。
文摘The ultrafast photoinduced strain(UPS)resulting from the coupling of piezoelectric and photovoltaic effects in ferroelectric has been focused in the last decade,endowing them with extensive applications including ultrafast optical memories,sensors and actuators with strain engineering.The mechanism of screening of the depolarization field by photoinduced carriers is generally accepted for UPS in ferroelectrics,while the thermal component of the strain is usually diluted as the offset and has not been systematically confronted,leading to unnecessary confusion.Herein,both the positive and negative thermal expansion effects in composite ferroelectric epitaxial films are investigated by use of high-repetition-rate ultrafast X-ray diffraction,along with the piezoelectric and photovoltaic effects.The coupling of the positive/negative thermal effects and the piezoelectric/photovoltaic effects in ultrafast strain is evidenced and can be regulated.The opposite lattice responses due to different thermal effects of the samples with different axial ratios are observed.The maximum UPS is up to 0.24%,comparable to that of conventional ferroelectric.The interaction between the thermal and ferroelectric effects in the induced strain could promote the diversified applications with the coupling of light,heat and electricity.
