Skip to main content

Laser and properties of a Laser beam

Laser→

LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. It is a device that produces a highly intense monochromatic, collimated, and highly coherent light beam. Laser action mainly depends on the phenomenon of population inversion and stimulated emission.

The first successful Laser is a solid-state laser which was built by TH Maiman in 1960 using Ruby as an active medium.

Note→

The laser has often been referred to as an optical MASER because it operates in the visible spectrum portion of the spectrum. In general, when the variation occurs below the infrared portion of the electromagnetic spectrum, the term MASER will be employed, and when stimulated emission occurs in the infrared, visible, or ultraviolet portion of the spectrum the term laser or optical MASER will be used.

Properties of a Laser Beam→

The laser beam has the following main characteristics properties:
  1. A laser beam has high directionality and can be emitted only in one direction. The divergence of the laser beam can be less than $10^{-5}$ radian. Due to high directionality, these beams can be focused in very small areas.

  2. A laser beam is very narrow and hence can travel long distances without any spread. The spectral width ($\Delta \lambda$)of a laser beam is of the order of $10^{-6} A^{\circ}$.

  3. A laser beam is highly monochromatic. Its monochromaticity is much more than that of any conventional monochromatic source.

  4. The laser beam has high intensity and high power levels that can produce a temperature of the order of $10^{4} \: ^{\circ}C$.

  5. A laser beam has a high degree of coherence. It is highly temporally and spatially coherent.

Labels:

Comments

Post a Comment

If you have any doubt. Please let me know.

Popular Posts

Numerical Aperture and Acceptance Angle of the Optical Fibre

Angle of Acceptance → If incident angle of light on the core for which the incident angle on the core-cladding interface equals the critical angle then incident angle of light on the core is called the "Angle of Acceptance. Transmission of light when the incident angle is equal to the acceptance angle If the incident angle is greater than the acceptance angle i.e. $\theta_{i}>\theta_{0}$ then the angle of incidence on the core-cladding interface will be less than the critical angle due to which part of the incident light is transmitted into cladding as shown in the figure below Transmission of light when the incident angle is greater than the acceptance angle If the incident angle is less than the acceptance angle i.e. $\theta_{i}<\theta_{0}$ then the angle of incidence on the core-cladding interface will be greater than the critical angle for which total internal reflection takes place inside the core. As shown in the figure below Transmission of lig
Post a Comment
click here »

Fraunhofer diffraction due to a single slit

Let $S$ be a point monochromatic source of light of wavelength $\lambda$ placed at the focus of collimating lens $L_{1}$. The light beam is incident normally from $S$ on a narrow slit $AB$ of width $e$ and is diffracted from it. The diffracted beam is focused at the screen $XY$ by another converging lens $L_{2}$. The diffraction pattern having a central bright band followed by an alternative dark and bright band of decreasing intensity on both sides is obtained. Analytical Explanation: The light from the source $S$ is incident as a plane wavefront on the slit $AB$. According to Huygens's wave theory, every point in $AB$ sends out secondary waves in all directions. The undeviated ray from $AB$ is focused at $C$ on the screen by the lens $L_{2}$ while the rays diffracted through an angle $\theta$ are focussed at point $p$ on the screen. The rays from the ends $A$ and $B$ reach $C$ in the same phase and hence the intensity is maximum. Fraunhofer diffraction due to
Post a Comment
click here »

Particle in one dimensional box (Infinite Potential Well)

Let us consider a particle of mass $m$ that is confined to one-dimensional region $0 \leq x \leq L$ or the particle is restricted to move along the $x$-axis between $x=0$ and $x=L$. Let the particle can move freely in either direction, between $x=0$ and $x=L$. The endpoints of the region behave as ideally reflecting barriers so that the particle can not leave the region. A potential energy function $V(x)$ for this situation is shown in the figure below. Particle in One-Dimensional Box(Infinite Potential Well) The potential energy inside the one -dimensional box can be represented as $\begin{Bmatrix} V(x)=0 &for \: 0\leq x \leq L \\ V(x)=\infty & for \: 0> x > L \\ \end{Bmatrix}$ $\frac{d^{2} \psi(x)}{d x^{2}}+\frac{2m}{\hbar^{2}}(E-V)\psi(x)=0 \qquad(1)$ If the particle is free in a one-dimensional box, Schrodinger's wave equation can be written as: $\frac{d^{2} \psi(x)}{d x^{2}}+\frac{2mE}{\hbar^{2}}\psi(x)=0$ $\frac{d^{2} \psi(x)}{d x
Post a Comment
click here »