Chapter 10.3 Laser Light
Diffraction grating separates the wavelengths emitted by white light. The array of wavelengths emitted by a white light is called its emission spectrum.
Every substance has a unique emission spectrum and this spectrum is what helped scientists develop the first model of the atom. In Bohr’s model of the atom, he stated that electrons existed in energy levels.
The lowest energy level is called the ground state. Energy levels above the ground state are called excited states.
Shroedinger created a modern model of the atom called the Quantum model. The Quantum model is based on waves.
Atoms emit energy when electrons drop from excited states to lower energy levels. After an atom is pushed to a lower energy level, light is emitted and this is called stimulated emission. stimulated emission
A device that produces light by amplification of stimulated emission of radiation is called a LASER. Laser light has 1 wavelength and so it is called monochromatic.
Laser light is highly directional, which means the emitted light travels in the same direction. Laser light is coherent, which means the emitted light is in phase.
Laser versus Flashlight
The rate of the radiant energy produced by a laser can be found with this equation: Radiant power = radiant energy / time Pwr = E / t
How long does it take a 100 W light bulb to radiate 1 J of energy? Pwr = E / t Pwr = 100 Watts, E = 1 J, t = ? 100 = 1 / t 100 (t) = 1 t =.001 second
The power density of a laser is much higher than normal lights. Equation to find power density = power density = radiant power / area
What is the power density of a 100 W light bulb with an area of 2000? Compare the bulb density to a laser with a 100 W and area of 2. Pwr Density = Pwr / Area Pwr Density of light bulb = 100 / 2000 =.05 Pwr Density of laser = 100 / 2 = 50
5 Applications for lasers include: Grocery Store Scanner Manufacturing – drilling, cutting, and welding Medical use - Bloodless scalpels in surgery, removal of tattoos, eye surgery Produce Holograms Create Compact Discs