Marek Daszkiewicz

A Two-Dimensional Diffraction pattern Sampling With Stationary Single Detector

The diffraction pattern analysis requires very well corrected lenses. The diffraction patterns are usually sampled by detector moved strictly in the Fourier plane or by especially desired multielement detectors. A new sampling method is proposed. In this method a stationary single detector is placed in the focus of transforming lens, while the sampled diffraction pattern is moved in the Fourier plane. The movement of a diffraction pattern can be obtained by illumination of the investigated structure with a parallel light beam, which changes its inclination to the optical axis of the transforming lens. Simple lenses and detectors for diffraction pattern analysis can be used. The experiments with two-dimensional samplinq have been performed. A continuous change of the illumination beam direction have been obtained by rotating, a glass wedge with variable convex angle. In this way the diffraction pattern is sampled along the Archimedean spiral trace. This type of sampling gives the light intensity distribution in the polar coordinates. Results of the experiments are presented. They show the possibility of application of this method in practice.

New approach for identifying the zero-order fringe in variable wavelength interferometry

The family of VAWI techniques (for transmitted and reflected light) is especially efficient for characterizing objects, when in the interference system the optical path difference exceeds a few wavelengths. The classical approach that consists in measuring the deflection of interference fringes fails because of strong edge effects. Broken continuity of interference fringes prevents from correct identification of the zero order fringe, which leads to significant errors. The family of these methods has been proposed originally by Professor Pluta in the 1980s but that time image processing facilities and computers were hardly available. Automated devices unfold a completely new approach to the classical measurement procedures. The Institute team has taken that new opportunity and transformed the technique into fully automated measurement devices offering commercial readiness of industry-grade quality. The method itself has been modified and new solutions and algorithms simultaneously have extended the field of application. This has concerned both construction aspects of the systems and software development in context of creating computerized instruments. The VAWI collection of instruments constitutes now the core of the Institute commercial offer. It is now practically applicable in industrial environment for measuring textile and optical fibers, strips of thin films, testing of wave plates and nonlinear affects in different materials. This paper describes new algorithms for identifying the zero order fringe, which increases the performance of the system as a whole and presents some examples of measurements of optical elements.

Overview of the measuring systems where a continuously altered light source plays a key role: Part I

The paper focuses on two families of instruments that have been developed over several years in the Institute of applied Optics using microinterferometric and confocal approach. The continuously variable light source constitutes the binding element of these two classes of measuring devices. The light source has to emit continuous spectrum. During measurements the selected wavelength must be determined with significant accuracy, which constitutes the key and critical factor of the measurement process as a whole. The described systems are only a small part of what photonics offers but are very useful in characterizing many objects and materials in research and industrial environment.

Multiwavelength laser scattering tomography

The phenomenon of laser light scattering provides the technology for visualization and testing the inner structure and homogeneity of materials. Some of them excited by the laser light in the tomographic process can emit light the wavelength of which is different than that of excitation laser. Such photoluminescence can be a source of additional information of the material’s structure. Combining the Laser Scattering Tomography (LST) and Spectrometry techniques has enabled us to develop a new type of an LST technique. The system is useful for investigations of various materials like semiconductors (Si, GaAs) ceramics, crystals for passive absorbers for high power pulse lasers, and laser crystals.

Fringe image analysis for variable wavelength interferometry

The paper presents a relatively simple though effective approach to fringe field processing for variable wavelengthinterferometry- related techniques including a detailed analysis of noise influence on the accuracy of fringe parameters extraction.

Photonic technology revolution influence on the defence area

Revolutionary progress in the photonic technology provides the ability to develop military systems of new properties not possible to obtain with the use of classical technologies. In recent years, this progress has resulted in developing advanced, complex, multifunctional and relatively cheap Photonic Integrated Circuits (PIC) or Hybrid Photonics Circuits (HPC) built of a collection of standardized optical, optoelectronic and photonic components. This idea is similar to the technology of Electronic Integrated Circuits, which has revolutionized the microelectronic market. The novel approach to photonic technology is now revolutionizing the photonics’ market. It simplifies the photonics technology and enables creation of technological centers for designing, development and production of advanced optical and photonic systems in the EU and other countries. This paper presents some selected photonic technologies and their impact on such defense systems like radars, radiolocation, telecommunication, and radio-communication systems.

Noise reduction in an optical emission spectrometer with rotating diffraction grating

The paper concerns the development of an optical emission spectrometer with a helium microwave rotating plasma as the excitation source which is an alternative to ICP spectrometers. In the new solution helium is used as the plasma and carrier gases, which helps to determine elements such as halogens and some non-metals. The new system should demonstrate decreased operating costs i.e. the flow of 1L He/min compared to about 15L Ar/min for ICP. Its spectral range is within 165 nm - 840 nm, sensitivity at the level of ppb and spectral resolution is equal to 0.01 nm. The system uses a set of two photomultipliers for VIS and UV regions. The entire spectrum is collected during a single rotation of the diffraction gratings. The paper describes the collection of algorithms developed to decrease noise and smooth spectral data.

Photonics approach to traffic signs

The automotive industry has been always a driving force for all economies. Despite of its beneficial meaning to every society it brings also many issues including wide area of road safety. The latter has been enforced by the increasing number of cars and the dynamic development of the traffic as a whole. Road signs and traffic lights are crucial in context of good traffic arrangement and its fluency. Traffic designers are used to treat horizontal road signs independently of vertical signs. However, modern light sources and growing flexibility in shaping optical systems create opportunity to design more advanced and smart solutions. In this paper we present an innovative, multidisciplinary approach that consists in tight interdependence of different traffic signals. We describe new optical systems together with their influence on the perception of the road user. The analysis includes maintenance and visibility in different weather conditions. A special attention has been focused on intersections of complex geometry.

Laser scanning tomograph as the tool for investigation of semiconductor materials

IR laser light scattering phenomena allows to visualize inhomogeneities in the bulk semiconductor materials. A device for observation of IR scattering in semiconductor wafers - the laser scanning tomograph (LST) - was designed and manufactured in the Institute of Applied Optics. A sample is illuminated by the diode pumped Nd:YAG laser, emitting the IR laser light in TEMoo mode. The laser beam diameter inside the semiconductor samples does not exceed 50 micrometers . The scattering centers inside the sample are observed perpendicularly to the direction of illuminating beam, using microscope with an IR CCD camera. To obtain a 2D image of scanned plane, the sample is moved horizontally by a scanning stage. The system has also a moving stage that allows to move the sample vertically. This enables the sample investigation in the third direction. The LST is controlled by a PC computer equipped with a user friendly software. The measurements results of GaAs wafers are presented.

Optoelectronic scanning device for the observation of scattering of YAG laser light in semiconductor materials

Infrared laser light scattering is a powerful tool for investigation of inhomogeneities in the bulk semiconductor materials. For sample illumination the diode pumped Nd:YAG laser emitting monomode 1.06 micrometers beam is used. The laser beam waist inside the semiconductor samples does not excess 50 micrometers . The scattered centers inside the sample are observed perpendicularly to the direction of illuminating beam using microscope with infrared CCD camera. To obtain 2D image of scanned plane the sample is moved horizontally by the scanning stage driven by computer. Controlled changing of scanning plane enables the investigation of the sample in the third direction. The scanning and scattered image processing are controlled by computer. The device is tested on GaAs wafers.