Summary
Highlights
Alano from Bidon State University Malay City Bidon introduces research on experiments in wave optics using a semiconductor diode laser. The video begins by explaining light interference, characterized by bright and dark fringes when light passes through single or multiple slits (diffraction gratings). Destructive interference creates dark fringes, while constructive interference produces bright fringes.
To observe interference, light sources must be coherent (constant phase) and monochromatic (single wavelength). Natural light, like sunlight, is incoherent and not monochromatic, making it unsuitable for interference experiments. While light bulbs produce monochromatic light, their intensity diminishes with distance due to the inverse square law.
Laser (Light Amplification by Stimulated Emission of Radiation) provides highly coherent and nearly monochromatic light. Semiconductor diode lasers are particularly useful, finding applications in CD/DVD players, laser printers, fiber optics, and alarm systems due to their precise properties.
The research aims to develop a laser setup with a semiconductor diode laser as the light source for interference and polarization experiments. Specific objectives include producing interference patterns, determining the laser beam's wavelength, measuring diffraction grating distances, and describing the relationship between polarization angle and light intensity according to Malus's Law.
The methodology involves using a semiconductor diode laser in a dark room. The setup for diffraction grating experiments (Figure 2) includes the diode laser, a diffraction grating, and a screen. The distance between the grating and screen (L) is measured, and pattern intervals are determined with a meter stick. Experiments also used a CD as a diffraction grating (Figure 4) and a setup for polarization studies (Figure 6) with a polarizer, analyzer, and a photo detector connected to a voltmeter.
Diffraction grating experiments consistently produced a central bright fringe flanked by symmetric sets of bright fringes. The first and second bright fringes from the center are denoted as first and second-order maxima. Scatter plots (Figures 9 and 11) show the relationship between pattern interval (ym) and distance (L), yielding regression equations for both diffraction grating and CD grating experiments.
The experiments showed low percentage errors (not more than 4%) for wavelength and grating distance calculations, which are acceptable for undergraduate laboratory levels. For polarization, a sinusoidal scatter plot (Figure 12) illustrates the relationship between intensity and angle. Figure 13 demonstrates a linear relationship between intensity and cosine squared of the angle, confirming Malus's Law and yielding a specific regression equation.
The diffraction grating experiments successfully produced characteristic diffraction patterns, yielding accurate laser beam wavelength values (within 3.2% error). The use of a semiconductor diode laser contributed to these accurate results due to its coherent and monochromatic properties. Similarly, CD grating experiments also provided highly accurate results. Furthermore, a strong positive correlation between intensity and cosine squared of the angle confirmed Malus's Law. It is recommended to develop and validate a manual containing experiments suited for the established setup.