$sound and light diffraction$

$sound and light diffraction$

Numerous traditional interferometers 1 are now in use for the mission of common man from research laboratories to flying satellites. Several techniques that use optical interference for the measurement of displacements and vibrations have been developed 2. Measurements of displacement and vibration have been an area of interest in many engineering problems using these two phenomena. Daniel Malacara 1 in his book detailed these phenomena, their differences, advantages and disadvantages and various instruments that are made for physical measurements. However, the two phenomena are so different and are so adequately explained in many text books. The diffraction pattern seen on any observation screen is really another interference pattern. In reality, there is no difference between the interference and diffraction pattern. The most striking examples are the interference and diffraction patterns often seen every day in experiments with light. When the laser beam is used for measurement applications, the spatial profile of the laser beam exhibiting particular distribution patterns and propagation properties in space and time are much more important. Controlling the profile of a laser beam in space and time is an important research challenge in optical technology. Lasers are predominantly used as diagnostic tools or as energy sources in scientific research exploration.

$sound and light diffraction$

The experimental results obtained here verify the efficacy of the proposed method indicating its suitability for a novel class of sensors to be employed in practical circumstances. Comparing to the established diffraction techniques employing edges, the proposed method is simple to implement and extends the measurement applications. The same photodetector responds to the dynamic intensity variations corresponding to the diffraction induced interference pattern and concurrently generates a dynamic electrical output. Diffraction and induced interference occur together at the sensing area of the photodetector. The method makes use of an innovative illumination of light beam in which the laser light is made to incident at the interface between the active and opaque regions of a photodetector. An optical method for simultaneous generation and detection of diffraction of light around the edges of photodetectors is reported in this paper along with its application for vibration sensing.

$sound and light diffraction$

Sound and light diffraction