Researches On The Scan Circuit Of Synchronous Scan Streak Camera

Synchronous scan streak camera is one kind of the image-converter streak cameras,it has a high sensitivity and a wide dynamic range.Therefore it has a unique advantage in high temporal resolution detecting in weak light.The principle of synchronous scan streak camera is that: The weak optical signal shine in photocathode periodically.Then the photoelectron,which produced by photocathode and went through accelerating and focusing,separate longitudinal in turn by the quasi linear region of the high frequency sine signal which being added on the deflection plate.At last,they accurate overlay on the screen,so as to realize the high speed detection of the weak periodical optical signal.From the above principle,the synchronous scanning streak camera’s temporal resolution mainly depends on the time jitter of the high frequency sine signal and the degree of precise synchronization between optical signals and the high frequency sine signal;besides,the Synchronous scan streak camera’s dynamic range of light intensity mainly depends on the frequency range of the high frequency sine signal.The high frequency sine signal is generated by the synchronous scan circuit module,therefore develop the high frequency high power and high stability scan circuit module of synchronous scan streak camera is a key point to improve the machine performance.It also has important significance for extending it’s application in the basic research field such as biological chemistry,photochemistry,optical physics and life sciences further on.This paper put forward a technology solution about synchronous scan streak camera’s scan circuit module at first.Mainly divided into three parts,the synchronous scan signal source,the RF power amplifier and the resonant cavity consists of a transmission line transformer,a adjustable high voltage capacitor and deflection plates.Next,the paper mainly introduced the design and development process of synchronous scan signal source which combined by phase locked loop(PLL)technology and direct digital frequency synthesis(DDS).Scan signal source using ADI AD9910 as the core chip in the design,with internal integrated PLL,further reducing the system cost and delay.Finally the system output any frequency sine signal in 50 MHZ to 300 MHZ frequency range,and modulate the frequency,amplitude and phase in real time by the host computer.In addition,S parameters and bandwidth of low-pass filter network in signal output circuit was also simulated by CST PCB STUDIO in this paper.According to the simulation,optimization design was carried out,so as to reduce the jitter time of the output signal further.The test result shows that the output sine signal’s jitter time is around 6 ps.Finally,the paper introduces the electromagnetic simulation of the resonant cavity consists of a transmission line transformer,a adjustable high voltage capacitor and deflection plates.The lengthways electric intensity between deflection plates at different frequency is simulated by the frequency domain solver of CST MICROWAVE STUDIO.The simulation results show that there will be equi-spaced resonance point between 50-300 MHZ,and there will be a peak electric intensity near the resonance point,bandwidth of curve will also be very narrow.The feasibility of this design was validated by the simulation results and we can do some further work in the theoretical basis.