Baoping Guo

Temporally and spectrally resolved sampling imaging with a specially designed streak camera.

We present a novel sampling imaging technique capable of performing simultaneous two-dimensional measurements of the temporal and spectral characteristics of light-emission processes by use of a specially designed streak camera. A proof-of-principle experiment was performed with a homemade multifocal multiphoton fluorescence microscope. The system was calibrated with a Fabry-Perot etalon and a standard fluorophore solution (rhodamine 6G in ethanol) and was shown to have temporal and spectral resolution of 6.5 ps and 3 nm, respectively, as well as high accuracy and reproducibility in lifetime and spectrum measurement. Temporally and spectrally resolved images of 4 x 4 foci on the sample can be obtained with a snapshot.

Opto-mechanical integrated analysis for optical system

High performance optical systems require integrated opto-mechanical analysis to predict performance. But, output from mechanical analysis cannot be used directly by optical simulation. This paper outlines the transmission method of mechanical analysis result to optical program. Zernike polynomials have corresponding meanings of Seidel aberrations and can be accepted by optical program, are used as tool to solve the data transmission problem among optical, mechanical and thermal program. Here, Thermal/Structural/Optical (TSO) integrated process; Zernike polynomials and its fitting method, fitting process are introduced.

Development of a multispectral multiphoton fluorescence lifetime imaging microscopy system using a streak camera

We report on the development of a multispectral multiphoton fluorescence lifetime imaging microscopy (MM-FLIM) system that is the combination a streak camera, a prism spectrophotometer, a femtosecond Ti: Sapphire laser and a fluorescence microscope. This system is versatile with multispectral capability, high temporal (10ps) and spatial (0.36μm) resolution and can be used to make 3-dimensional (3D) (x-y-z) multiphoton fluorescence intensity, spectrally resolved intensity and lifetime measurements with a single detector. The system was calibrated with a F-P etalon and a standard fluorescent dye and the lifetime value obtained was in good agreement with the value reported in the literature. Preliminary results suggest that this MM-FLIM system has integrated high temporal, spatial, and spectral resolution fluorescence detection in one microscopy system. Potential applications of this system include multiwell imaging, tissue discrimination, intracellular physiology and fluorescence resonance energy transfer imaging.

Theoretical and experimental study of a new picosecond and nanosecond framing camera

On the basis of theoretical and experimental study a new picosecond and nanosecond framing camera has been developed. The details associated with the design features of a framing image tube and its controlling circuitry are outlined and the experimental results obtained with this camera are shown in this paper. Recently experimental results have shown that this camera can provide 25 lp/mm, 17 lp/mm and 12 lp/mm with the exposure time (FWHM) of 5 ns, 250 ps, and 77 ps for each of 3 framing images, respectively. The pulse circuit for 6 frame images has been developed and the camera equipped with this circuit is being further tested. It is expected to obtain the same performances as stated above. This camera also can be used as a picosecond streak camera.

Octagonal pyramid optical splitting system in nanosecond framing camera

The high-speed photography is essential diagnostic tool in research on the ultra fast process. Usually, such process has the duration of hundreds nanoseconds to dozens microseconds. The image diagnostic instrumentation is required to obtain high speed framing images, which should be in fixed time in the duration with short exposure time and suitable gap. A kind of nanosecond framing camera has been developed, which uses octagonal pyramid mirror to split one image to eight. One image is split to eight in the space and each split image has equal optical energy. A nearly-pasted image intensifier with gate selection is also developed to enhance the weak optical image. Each channel uses independent image intensifier with gate and CCD camera. This system can capture eight images one time in the minimum interval time of 10ns while the exposure time is 3ns The framing speed achieves 100 million/second. The dynamic spatial resolution achieves 15 lp/mm. Many experiments, such as beam diagnose of electron pulse, plasma luminescence process have adopted this camera and many useful results have been obtained.

Recent advance in streak and framing cameras in Shenzhen University

In this paper, we report on the recent development of streak and framing camera techniques in Shenzhen University, such as soft X-ray streak image tube, synchroscan streak image tube, image intensifier and different kinds of newly developed electronic circuits. In particular, we present three different kinds of streak and framing cameras, including a soft X-ray streak camera with slit length of 30mm, dynamic spatial resolution of 15lp/mm and dynamic range of larger than 900; a specially designed synchroscan picosecond streak camera with a repetition rate of 1MHz, which can provide simultaneous time- and spectrum-resolved two-dimensional(2D) sampling information for biomedical imaging; and an 8 channel framing camera with exposure time of 3ns and dynamic spatial resolution of better than 20lp/mm.

A sort of pulsed microfocal x-ray source

A sort of pulsed microfocus x-ray source has been theoretically and experimentally studied. The portable x-ray source is composed of three portions: LaB6 crystal cathode electron gun emitting system, electrostatic focusing system, and metal target system. The electrons are emitted form the hot crystal cathode, and controlled by modulated Wehnelt grid bias value and the ratio Dw/H, and concentrated by two-equal-radius-cylinder-electrodes focusing system. The x-ray photons are irradiated by high energy electron beam bombarding metal target. The new x-ray sources general-purpose capabilities such as pulsed radiation, focal spot size and luminance were preliminary tested. When the temperature of LaB6 cathode is about 1900K and partial pressures being kept below 10-7 torr, the minimal focus diameter is merely about 10 microns with the pulse width 65ms.

Zernike Polynomials for Evaluation of Optical System in Use

Affected by working condition, performance of optical system will decline, especially for large system or system in bad and complex condition. Integrated analysis can predict its performance through multi-subject engineering analysis. Thermal\structural\optical(TSO) integrated analysis is typical[1]. The key problem in TSO process is data transmission among optical, mechanical and thermal programs. Each item of Zernike polynomials has corresponding meanings with Seidel aberrations and is widely used in project, optical design software and interference checks. It is convenient and mature to use Zernike polynomials as data transmission tool between optical and structural analysis program. In TSO process, the principle, fitting method and fitting process of Zernike polynomials are outlined. This method was successfully used in some optical systems design and fabricates process.

Development of a Simultaneously Time- and Spectrum-Resolved Multifocal Multiphoton Microscopy System Using a Streak Camera

We report the development of a multifocal multiphoton microscope (MMM) system using a specially designed streak camera, which is capable of providing simultaneously time- and spectrum-resolved fluorescence microscopy. Temporal and spectral resolutions of the system have been calibrated to be 6.5-200 ps and 1-3 nm respectively. We demonstrate the applicability of the system to spectrum-resolved fluorescence and lifetime imaging with fluorescent dyes, fluorescent microspheres. Potential applications of the system include the measurement of tissue pathology, intracellular physiology etc.

Improvements of UV/x-ray framing image tube cameras

The framing image tube camera has some intrinsic advantages. It has got some applications in ICF and X-ray laser field. But there are two main problems with this technique: the loss of spatial resolution at short exposure time,a nd the electromagnetic disturbance in the experimental area. In order to solve these problems, we have taken several measures: to improve the design of the image tube and the electronics and to strengthen the shielding. Additionally, in intense X-ray pulse we use MgF2 as cathode material instead of Au and CsI to reduce the space charge effects. The experiments in high power laser area have shown that 3 frame images can be provided with 75 ps (FWHM) exposure time and dynamic spatial resolution of 6 lp/mm. Some physics results of high power laser-plasma interaction have also been obtained.