In this paper, a light box for investigation of characteristics of optoelectronic detectors is described. The light box consists of an illumination device, an optical power sensor and a mechanical enclosure. The illumination device is based on four types of high-power light emitting diodes (LED): white light, red, green and blue. The illumination level can be varied for each LED independently by the driver and is measured by optical power sensor. The mechanical enclosure provides stable mounting points for the illumination device, sensor and the examined detector and protects the system from external light, which would otherwise strongly influence the measurement results. Uniformity of illumination distribution provided by the light box for all colors is good, making the measurement results less dependent on the position of the examined detector. The response of optoelectronic detectors can be investigated using the developed light box for each LED separately or for any combination of up to four LED types. As the red, green and blue LEDs are rather narrow bandwidth sources, spectral response of different detectors can be examined for these wavelength ranges. The described light box can be used for different applications. Its primary use is in a student laboratory setup for investigation of characteristics of optoelectronic detectors. Moreover, it can also be used in various colorimetric or photographic applications. Finally, it will be used as a part of demonstrations from the fields of vision and color, performed during science fairs and outreach activities increasing awareness of optics and photonics.
Uniformity of display luminance and color is important for comfort and good perception of the information presented on the display. Although display technology has developed and improved a lot over the past years, different types of displays still present a challenge in selected applications, e.g. in medical use or in case of multi-screen installations. A simplified 9-point method of determining uniformity does not always produce satisfactory results, so a different solution is proposed in the paper. The developed system consists of the large-format X-Y-Z ISEL scanner (isel Germany AG), Konica Minolta high sensitivity spot photometer-colorimeter (e.g. CS-200, Konica Minolta, Inc.) and PC computer. Dedicated software in LabView environment for control of the scanner, transfer the measured data to the computer, and visualization of measurement results was also prepared. Based on the developed setup measurements of plasma display and LCD-LED display were performed. A heavily wornout plasma TV unit, with several artifacts visible was selected. These tests show the advantages and drawbacks of described scanning method with comparison with 9-point simplified uniformity determining method.
In recent years, many scientific and industrial centers in the world developed a virtual reality systems or laboratories. One of the most advanced solutions are Immersive 3D Visualization Lab (I3DVL), a CAVE-type (Cave Automatic Virtual Environment) laboratory. It contains two CAVE-type installations: six-screen installation arranged in a form of a cube, and four-screen installation, a simplified version of the previous one.
The user feeling of “immersion” and interaction with virtual world depend on many factors, in particular on the accuracy of the tracking system of the user. In this paper properties of the tracking systems applied in I3DVL was investigated. For analysis two parameters were selected: the accuracy of the tracking system and the range of detection of markers by the tracking system in space of the CAVE.
Measurements of system accuracy were performed for six-screen installation, equipped with four tracking cameras for three axes: X, Y, Z. Rotation around the Y axis was also analyzed. Measured tracking system shows good linear and rotating accuracy. The biggest issue was the range of the monitoring of markers inside the CAVE. It turned out, that the tracking system lose sight of the markers in the corners of the installation. For comparison, for a simplified version of CAVE (four-screen installation), equipped with eight tracking cameras, this problem was not occur. Obtained results will allow for improvement of cave quality.
At present, one of the most advanced virtual reality systems are CAVE-type (Cave Automatic Virtual Environment) installations. Such systems are usually consisted of four, five or six projection screens and in case of six screens arranged in form of a cube. Providing the user with a high level of immersion feeling in such systems is largely dependent of optical properties of the system. The modeling of physical phenomena plays nowadays a huge role in the most fields of science and technology. It allows to simulate work of device without a need to make any changes in the physical constructions.
In this paper distribution of luminance in CAVE-type virtual reality systems were modelled. Calculations were performed for the model of 6-walled CAVE-type installation, based on Immersive 3D Visualization Laboratory, situated at the Faculty of Electronics, Telecommunications and Informatics at the Gdańsk University of Technology. Tests have been carried out for two different scattering distribution of the screen material in order to check how these characteristicinfluence on the luminance distribution of the whole CAVE.
The basis assumption and simplification of modeled CAVE-type installation and results were presented. The brief discussion about the results and usefulness of developed model were also carried out.
Photography is a unique rapidly growing interdisciplinary field encompassing aspects of science, art and technology. Expectations of photographers are steadily increasing with the development of technology. One of the areas playing a crucial role in photography is lighting. Consequently, several types of light sources for photographic use have been developed. The ongoing research in this field concentrates on lamps with tunable CCT (Correlated Color Temperature). In this paper, we present a lamp, which emission spectrum can be tailored without affecting the output luminous ux. Intended for photographic uses, the lamp is based on an integrating sphere and a selection of LEDs. As the LED drivers, DC-DC converters controlled by a Raspberry PI were applied. Design process, including the selection of LED wavelengths, is presented. Output characteristics of the lamp were measured using the setup containing the spectrometer. The results of these experiments show good agreement with the spectrum set on the microcomputer.
An optoelectronic system for measurements of hematocrit level (HCT) in the whole human blood is presented. Proposed system integrates a dedicated optoelectronic sensor, a microcontroller and a small LCD display in a low cost, battery-powered, handheld device. Chosen method for determining blood hematocrit level is based on optical properties of whole blood in visible and NIR wavelength range. Measurements with the use of proposed system require blood samples (small drop in the range of microliters) which is placed in the micro cuvette. Then, absorption of the sample is measured at wavelengths of 570 nm and 880 nm. Prototype of the device was build and tested. Test results confirmed proper operation of the device with correct metrological parameters in application to HCT level measurements. Such a portable device can be used as a tool of bedside diagnosis, which becomes interesting alternative to full laboratory tests.
Opto-chemical sensors are sensors of quantities (pH level, heavy metal ions concentration), detection of which can be performed optically. These sensors utilize various optical phenomena such as changes of fluorescence in the presence of a certain agent. Many substances available and interesting from the sensor point of view exhibit different properties in solution and after physical and/or chemical mounting on glass slide or optical fiber. Because of this it is necessary to investigate application possibilities of a certain substance in well defined metrological environment. In this paper we described system for measuring fluorescence of sensing materials. We proposed system utilizing emission and absorption spectra separation and phase-sensitive detection. As an example of such system a fluorescence sensor of cobalt was of our interest. We described sample preparation process and measured some properties of chosen chemical substances. Achieved results are the basis for further research.
An application for modeling of polarimetric sensors is presented. Written using industry-standard LabVIEW platform, this application calculates response of a non-ideal sensor using a monochromatic source to force acting on the modulator. Problems existing when creating a modeling application in a graphic programming environment are discussed. Selected results of optical fiber sensors modeling are presented.
In recent years an increasing interest in passive multiband systems for temperature and emissivity measurement was noted. However, available literature about passive multiband systems concentrated exclusively on problem of temperature measurements with these systems in situation when these systems can be also used for non-contact emissivity measurements. Modeling of such systems, what is usually the first stage of system designing, requires acceptation of several simplifications and approximations. In this paper an experimental verification of modeling results is performed based on developed measurement setup. Obtained results are in good agreement with results of previously performed computer analyses that shows usefulness of multiband method for emissivity measurements in working conditions.
Recent studies about non-contact temperature measurement concern passive multiband radiometric systems. These systems give a potential possibility of accurate temperature measurements in case of unknown and wavelength depended emissivity of the examined object. Modeling of such systems, what is usually the first stage of system designing, requires acceptance of several simplifications and approximations. In this paper an experimental verification of modeling result is performed. Based on developed experimental setup some tests are performed. It allows us to determine some systems parameters and whole system estimation.
During last decade an increasing interest in passive multiband systems for temperature measurement was noted. However, recent studies showed that multiband systems are capable of producing accurate results of non-contact temperature measurement only in limited number of applications. Available literature about passive multiband systems concentrated exclusively on problem of temperature measurements too. A model of a passive multiband system for non-contact emissivity measurement has been developed and presented in this paper. Simulations carried out using this model showed that it is possible to achieve reasonable accuracy of emissivity measurements with passive multiband systems and these systems can be considered as an attractive solution for emissivity measurements in industrial conditions.
In this paper we describe an idea of a multiband system for non-contact temperature measurement and analytic techniques which allow calculate temperature and emissivity of the examined body from the measured data. Influence of some factors on measurement accuracy is discussed. Described technique gives a possibility to optimize construction of the whole system.
An interferometric optical fiber sensor intended for use in Weigh-in-Motion systems is presented. The sensor uses a modified Michelson interferometer configuration with two sensing arms. To avoid polarization induced fading the force acting on the sensor is measured indirectly, using modulators which convert it to pressure. Operation of such modulators was verified by experiment and based on its results a laboratory model of a sensor was built and tested.
The requirements for design and construction of fiber optic measuring heads (probes) based on an imaging rigid fiber optic bundle and on flexible fiber optic bundles are presented. The models of the probes and their application in a spectrophotometric measurement system for a medical application are described and discussed. The performed experiments confirmed their usefulness.
The widespread migration to the Wavelength Division Multiplexing telecommunication systems stimulates the demand for tunable external cavity semiconductor lasers used for production testing and maintenance purposes. As these lasers have a coherence length of hundreds meters and their prices are continually decreasing, it can be predicted that these lasers will soon be commonly used as a source in interferometric and polarimetric sensors. In this paper we present the theoretical description of a distribution optical fiber sensor using polarization mode coupling in a polarization maintaining optical fiber. The performance of the sensor using a tunable semiconductor laser is analyzed and the possible applications of this type of sensor are discussed.
In the paper a setup for the measurement of instant velocity of samples subjected to breaking test is described. It was estimated that the maximum speed of deformation is 50 m/s and maximum strain is 5 mm. An optical method has been selected and a measurement setup was built. We discuss the setup performance and the measurement results.
Stress sensors dedicated for Weigh-in-Motion of road vehicles should exhibit high dynamic range, good accuracy and repeatability, as well as long service life. One of the most promising group of sensors for this application are polarimetric sensors, due to their simplicity and high sensitivity. Preliminary measurements of the optical fiber properties in this application resulted in significant hysteresis being observed even for relatively low stress, which is probably caused by the cladding properties or by the construction of the modulator used in the measurement.