Measurements of the temporal and spatial resolution of a PS-1/S1 image-converter camera, depending on the scanning speed, were performed. The camera has a PIF-01 electron-optical converter with deflecting plates of the capacitor-type scan. It is shown that obtaining the minimum half-width of the space–time response function in two mutually perpendicular directions (time and space) can be achieved by selecting an optimal voltage at the focusing electrode. The difference between the optimal static and dynamic voltages of focusing in space and time was determined experimentally, which was 450 V for a scanning speed of 1.56 × 10 10 cm/s. Computer modeling of the processes that affect the optimal resolution was performed.

A point source of X-ray radiation with an energy range of up to 40 keV has been developed on the basis of a specially designed image converter tube. The source is capable of operating in pulsed and continuous modes. The main purpose of this is to use the source for testing X-ray streak cameras. The device can also be used in X-ray microscopy and spectroscopy as a reference radiation source, in biomedical research, and in other fields.

A dual-slit dissector operating in the crossed-sweep mode with a picosecond time resolution has been created on the basis of the PIF-01 image converter tube. The dissector is applicable to synchrotron radiation sources and electron-positron colliders when it is necessary to simultaneously record longitudinal profiles of multi-bunch beams that fill two to several hundred adjacent separatrices of an accelerator ring. Two trains of light pulses shifted in time with respect to each other have been recorded with a time resolution of 6.0 ± 0.5 ps during the dynamic tests of the developed dissector with a laser system.

A new-generation dissector has developed on the basis of a modified PIF-01 image converter tube for the timing diagnostics of charged particle beams in accelerators. Pilot models of the detector have been produced. The time resolution obtained in the dynamic tests at the laser facility is ~2 ps, which is better by more than an order of magnitude than the corresponding parameter of the available LI-602 dissector. The pilot models of the new dissector have been successfully tested in experiments at the Metrology Light Source (MLS) accelerator (Berlin, Germany).

A laser electron source localised on a photocathode surface was developed on the basis of Ag and Cu2O thin films sequentially deposited by magnetron sputtering on a glass substrate. Photoemission of electrons under the action of the fourth (263 nm) harmonic of a femtosecond fibre laser was initiated from the surface of an Ag film deposited on the substrate surface. Photoelectron source localisation on the photocathode surface was provided by sputtering the Cu2O copper oxide film on its surface, which significantly (about 50 times) reduced the photoemission efficiency, and by subsequent removal of the copper oxide layer in the photoemission spot with a diameter of similar to 15 mu m by means of focused second-harmonic radiation of a femtosecond fibre laser. In conducting research on the photocathode surface, a grid of photoemission spots was formed, which greatly facilitated the laser beam alignment with the photoemission spot. A decrease in the noises of ultrafast transmission electron microscope, associated with spatial fluctuations of the laser beam initiating pulsed photoelectron emission from the microscope photocathode when using a localised electron source on the basis of a structure of thin Cu2O and Ag films, was experimentally demonstrated.

We have developed an ultrafast transmission electron microscope for studying dynamic processes in samples excited by femtosecond laser pulses and for probing transient processes occurring under irradiation by a pulsed (~7 ps) photoelectron beam with an adjustable delay with respect to the excitation pulse. A 75-keV photoelectron beam is formed using a silver photocathode irradiated by a femtosecond laser beam. This microscope is shown to have a high spatial resolution in the photoelectron regime: nanoscale in the imaging regime and atomic in the electron diffraction regime. It is used for experimental observation of ultrafast interaction of a laser-induced electron cloud with a pulsed photoelectron beam. Using this effect, a method of spatial and temporal alignment of excitation laser and probe electron pulsed beams on a sample is experimentally implemented.

Numerical modelling is used to analyse some effects restricting the enhancement of temporal resolution into the area better than 100 fs in streak image tubes and photoelectron guns. A particular attention is paid to broadening of an electron bunch as a result of Coulomb interaction. Possible ways to overcome the limitations under consideration are discussed.

The principles of simultaneous spatial and temporal focusing of photoelectron beams in nonstationary electric fields are theoretically studied and experimentally realised as applied to time-analysing image-converter tubes (ICTs). It is theoretically shown that the use of nonstationary focusing electric fields makes it possible to surpass the theoretical time resolution limit of ICTs (10(-4) s) determined for stationary fields by Zavoisky and Fanchenko in the 40s-50s of the last century. The possibility of forming electron packets with an energy of 10-30 KeV and a subfemtosecond duration (below 10(-15) s) gives impetus to the development of time-resolved electron diffraction, which is a direct method of investigation of atomic-molecular dynamics in solid and gaseous media.

In real quasi-two-dimensional semiconductor nanostructures (quantum wells, quantum dots), the transverse g -factor of holes is a stochastic quantity. This fact should be taken into account in analyzing the optical orientation and Hanle effect of holes. The Hall effect for an ensemble of particles with a “random” g -factor has been treated theoretically. In the case where the spin relaxation time of a hole with a characteristic g -factor is shorter than the hole lifetime, there can occur a narrowing of the depolarization contour and an increase in its amplitude. In the opposite case of long spin relaxation times (trions in quantum dots), a formula has been derived, which generalizes the previously obtained result to the case of an arbitrary tilt angle of the magnetic field with respect to the plane of the layer (Hanle effect in the tilted form).

In the present communication we describe the design of the sub-100 fs streak-tube that may be used for commercial streak cameras manufacturing. Careful attention is paid to preparing of a very smooth input photocathode substrate on which a low surface resistance (1-5 Ohm/) photocathode of S-1 type is deposited. Our estimations have shown that the photocathode surface roughness of about tens of nanometers may restrict the ultimate time resolution at the level of 100 fs. This is the reason why the photocathode substrate surface has to be smooth within the units of nanometers. The curvature of the photocathode surface is also very important to compensate the difference in the time-of-flight of electrons emitted from the central and peripheral photocathode areas. Further modernization was conducted with a photocathode-accelerating mesh assembly. The assembly may operate with 2 - 3 ns (FWHM) electrical pulses of 12 - 15 kV amplitude. In order to improve the S/N ratio in the streaked images, a shuttering system was incorporated inside the tube. As the result, a completely new femtosecond streak tube of PV-FS-M type was designed, manufactured, and tested.

The paper reports on the development of a new streak image tube with accelerating mesh and large (18 mm) photocathode work area. The tube's temporal resolution is close to one picosecond. To govern photoelectronic images the tube possesses shutter and deflector plates. Its geometric design allows uniform spatial resolution (more than 25 lp/mm) along the entire photocathode work area at 1.3 electron-optical magnification and negligibly small distortion. Being a continuation of the well-known PV and PIF - type streak image tubes developed in due time in GPI, the tube represents a promising tool for taking pictures of ultrafast processes in wide radiation spectrum range.

In contrast to the conventional image intensifier with large work area, a streak image tube should possess additional important feature - the comparatively small temporal distortion at the entire work area of the photocathode. With this additional engineering restriction taken into account, a novel small-size meshless streak image tube has been developed by means of numerical optimization. The tube with 25-mm wide work area contains a pair of deflection plates to sweep the electron image along the 25 mm output phosphor screen that is separated by 100 mm from the photocathode. The electron image can be shuttered with a 300 V blanking electric pulse. Electron-optical magnification of the tube is unit; spatial resolution reaches 30 lp/mm over the entire photocathode work area; temporal resolution lies in the 20 - 50 ps range, depending on the accelerating voltage (6 - 15 kV).

The effect of phase modulation (resulting in a chirp of an ultrashort laser pulse) on the generation of a coherent A(1) phonon in Te was studied. The amplitude of coherent oscillations was found to depend on the sign and value of the pulse chirp: the oscillation amplitude decreases as the chirp increases. For a positive chirp, this effect is twofold stronger than for a negative one. The frequency-resolved response of a bandwidth-limited pulse was studied, which revealed the difference of oscillations and the relaxation response for the Stokes and anti-Stokes frequencies. The detected phenomena can be used for coherent control of lattice dynamics.

The authors have studied the influence of chirped laser pulses on the coherent phonon generation in single crystal Te. They have shown that the pulse chirp affects the amplitude of coherent phonons with A1 symmetry in the case of intense excitation only. By varying the chirp of an intense exciting pulse, the authors demonstrated that negatively chirped pulses are almost twice more effective in the creation of lattice coherence than positively chirped pulses.

In this paper, we analyse the applicability of dynamic speckles for distance measurement to any rough surface. The technique is based on spatial filtering of a speckle pattern generated when the object surface is scanned by a laser beam deflected from an acousto-optic device. An extremely short response time was achieved because of the high scanning speed provided by the acousto-optic deflector. We have developed a prototype of the distance-measuring system and studied its performance. The measurement setup has a very simple configuration. The distance can be measured within as short a time as 50 ns, but with rather high inaccuracy caused by the stochastic nature of the speckle effect. The data averaging is easily implemented within a single scan and allows us to achieve an accuracy of 110 µm within the time window of 2.5 µs. An analysis of the factors affecting the performance of the proposed technique is carried out. It is shown that the response time can be diminished by an order of value using an acousto-optic crystal with higher acoustic speed. The proposed technique may be useful for monitoring the geometrical parameters of fast moving or rotating surfaces in various industrial applications.

We propose novel technique for z-distance measurement to an optically rough surface using dynamic speckles. The technique is based on the continuous frequency measurements of the power modulation of the spatially filtered scattered light. The dynamic speckle pattern is created when the laser beam scans the surface under study. We use an acousto-optical deflector to perform scanning the surface. Acousto-optical deflector provides the surface scanning at very high speed of 200 m/s. The complete optical-electronic system was designed and fabricated for measuring acquisition of two instant coordinates of the surface into a computer. The response time of the z-distance sensor in our first experiments is 16 microseconds. However, it is shown that the response of the sensor may be as fast as 100 nanoseconds. First measurements of the surface profile using fast scanning of the laser beam were experimentally demonstrated. The proposed technique can be very useful for monitoring the surface profile and/or vibrations of the fast moving or fast rotating surfaces in various industrial applications.

In the paper new theoretical aspects of temporal focusing of photoelectron bunch in time-dependent fields are elucidated. The results of computer modeling on electron-optical system with combined time-dependent electric and static magnetic fields which ensure both spatial focusing of the bunch and its temporal compressing up to the sub-femtosecond level are presented.

The problem of ideal first-order temporal focusing of photoelectron bunches with quasi-stationary electromagnetic fields is discussed on the basis of theoretical electron optics and computer modelling.