Heisenberg's uncertainty principle explains single slit diffraction1 where maximum is always at the centre. The same
experiment has been conducted but with transparent walls i.e. the material present on either side of the slit, instead of
opaque material. The observed result is a minimum at the centre in between two maximum. It is intuitive that atleast
some photons passed through the slit must end up at the centre of the diffraction pattern but the result is different. The
diffraction pattern occurs as the photons interact with the material around the slit. While uncertainty principle cannot
give quantitative explanation as the photons confined in gap between slits still occupy the same space whether it is
passing through a slit or not. This paper discusses various experiments and results by examining the interactions between
photons and the material of the wall which makes the slit for better understanding of properties of light.
Tunable LASER source is a device which emits a particular light wavelength based on the tuning done. The tuning depends on certain characteristic of the LASER source which makes it customised within a gamut of wavelengths. Most Conventional LASER sources in the market are bulky and complex. The Tunable LASER source designed is established on the simple idea that Optical Amplifier can act as a broadband source, and temperature and strain sensitive Fiber Bragg Grating can be used to filter the required wavelength. This makes the design very light and elementary.
Pressure and temperature are fundamental properties of the oceanic water. They have varying effects on the processes that take place in oceans be they biological, physical or chemical while pressure always increases with respect to surface when you go down, temperature has a more complex variation with respect to the depth. Various tools and techniques are available to measure these properties. A combination sensor with high accuracy and response time would enable better measurements of these two parameters. This paper presents a novel structure based on simultaneous measurement of temperature and pressure sensing using Fiber Bragg grating (FBG) sensors. For this, proposed sensor heads for both temperature and pressure. Temperature measurement, two different types of sensor heads has been designed for this implementation. The first sensor head consists of a FBG which is fixed between ceramic block on one side and a bimetallic strip made up of aluminum and copper on the other. The second sensor head consists of the FBG which is fixed between two bimetallic strips. For pressure, in first type the FBG is fixed between silicon rubber foil and sensor head wall. In second method the FBG is fixed between two silicone rubber foils. The pressure on walls of silicon rubber foils elongates FBG, which results in shift of wavelength. Theoretical studies carried out on these proposed sensor heads resulted in an increase in temperature sensitivity of about six times greater than that of bare FBG sensor and pressure sensitivity of about eight times greater than that of bare FBG. Further, the proposed sensors have shown good linearity and stability.
This is the study of relation between thermal and magnetic properties of permanent magnets. The concept of adiabatic demagnetization gives the basic idea on variation in temperature of paramagnetic substances due to the application of magnetic field. With the understanding of adiabatic demagnetization the variations in temperature of ferromagnetic materials can be explained. In both cases, adiabatic demagnetization tells us about conservation of energy. The study on thermal properties of ferromagnetic materials at cryogenic temperatures gives the amount of thermal energy being transferred from or to the surroundings and hence gives the variations in magnetic fields due to temperature changes. As samarium cobalt rare earth permanent magnet do quite well at cryogenic temperatures, this study is much useful in future applications of permanent magnets in space for a renewable energy source. This will enable us to look into the design and working of a device that can convert thermal energy to mechanical energy which leads to thinking of energy conversion without causing harm to our environment. Numerous research works report the successful use of samarium cobalt to temperatures as low as 2 K.