RES.6-006 | Spring 2008 | Undergraduate
Video Demonstrations in Lasers and Optics

Demonstrations in physical optics

VIDEOS DESCRIPTIONS
I. Demonstrations in physical optics
Optics: polarization of light and polarization manipulation
Linear polarizer

Description of a linear polarizer

Use of a linear polarizer to analyze the state of polarization of light from a laser

Demonstration of the change in the state of polarization of light after reflection by two aluminum coated mirrors

Use of a linear polarizer to set the state of polarization of light

Polarization rotation using polarizers

Rotation of the plane of polarization of light using a single linear polarizer

Limitation of the single polarizer method

Rotation of the plane of polarization using two linear polarizers

Effect of polarization rotation on transmitted intensity

Quarter-wave plate

Description of a quarter-wave plate

Use of a quarter-wave plate to change the state of polarization of light, e.g., from linear to elliptical (or to circular) polarization

Demonstration that there is no change in the state of polarization when propagating along either principal axis of the quarter-wave plate

Half-wave plate

Description of a half-wave plate

Use of a half-wave plate to rotate the plane of polarization from zero to ninety degrees with very little loss

Demonstration that there is no change in the state of polarization when propagating along either principal axis of the half-wave plate

Optical isolator

Need for an optical isolator

Demonstration of the performance of an optical isolator using a quarter-wave plate and a linear polarizer

Scattered light in a dielectric

Propagation of linearly polarized light in a dielectric (Lucite) rod

Observation of Rayleigh scattered light within rod

Demonstration that the state of polarization of the scattered light is the same as that of the incident light

Optics: reflection at dielectric interfaces
Reflection at the air-glass boundary

Reflection and transmission of light at an air-glass boundary as a function of the angle of incidence (0-90º) for different states of polarization of the incident light

Demonstration of Brewster’s angle

Reflection at the glass-air boundary

Reflection and transmission at a glass-air boundary as a function of angle of incidence (0-90º) for different states of polarization of the incident light

Demonstration of the critical angle

Demonstration of the propagation of the transmitted beam along the boundary at the critical angle

Demonstration of Brewster’s angle

Phase shifts in total internal reflection

Demonstration of the absence of any change in the state of polarization of the reflected and transmitted light at a glass-air boundary below the critical angle

Demonstration of the change in the state of polarization of reflected light at a glass-air boundary above the critical angle, i.e., in total internal reflection

Application of this effect to making quarter-wave and half-wave plates

Optics: two-beam interference
Two-beam interference — collimated beams

Demonstration of two-beam interference using collimated beams in a Michelson interferometer

Demonstration of various fringe patterns as a function of the alignment of the interferometer mirrors

Effect of mirror translation on fringe pattern using a piezoelectric driver

Two-beam interference — diverging beams

Demonstration of two-beam interference using diverging beams in a Michelson interferometer

Demonstration of various fringe patterns as a function of the alignment of the interferometer mirrors

Change in fringe pattern as a function of path length difference

Destructive interference — Where does the light go?

Demonstration of constructive and destructive interference in a Michelson interferometer using diverging beams

Demonstration of complete destructive interference between the two beams leaving the interferometer for equal path lengths

Where does the light go in destructive interference?

Demonstration that there is light in each arm of the interferometer in destructive interference

Demonstration of light reflected back toward source simultaneously with light transmitted from interferometer for equal paths and also for unequal paths of the interferometer

Fringe contrast — vibrations

Demonstration of two-beam interference in a Michelson interferometer with collimated beams

Effect of vibrations on fringe contrast

Fringe contrast — intensity ratio

Demonstration of two-beam interference in a Michelson interferometer with collimated beams

Effect of intensity difference between interfering beams on fringe contrast

Fringe contrast — polarization difference

Demonstration of two-beam interference in a Michelson interferometer with collimated beams

Determination of the state of polarization in each arm of the interferometer

Demonstration of the rotation of the plane of polarization in one arm of the interferometer using a quarter-wave plate

Demonstration of the effect of polarization difference on fringe contrast, showing zero contrast for orthogonal polarizations

Fringe contrast — path difference

Demonstration of two-beam interference in a Michelson interferometer with collimated beams

Demonstration of the effect of path length difference (0-100 cm) on fringe contrast

Demonstration of the spectrum of the light source, in this case, a multilongitudinal mode He-Ne laser

Relationship between fringe contrast, path length difference, and spectrum of the light source

Coherence length and source spectrum

Demonstration of two-beam interference in a Michelson interferometer with collimated beams

Demonstration of fringe contrast with path length difference for a single-frequency laser light source

Demonstration of fringe contrast with path length difference for two- and three-frequency laser light sources

Relationship between fringe contrast and coherence length

Optics: multiple beam interference
Plane mirror cavity — collimated beams

Demonstration of multiple beam interference using a plane mirror cavity in transmission with mirror separation of 3 mm and collimated incident beam

Observation of finesse, free spectral range, and effect of cavity misalignment

Demonstration of multiple beam interference in reflection using the same cavity

Simultaneous observation of multiple beam interference in transmission and in reflection

Plane mirror cavity — diverging beams

Demonstration of multiple beam interference using a plane mirror cavity in transmission with a mirror separation of 3 mm and a diverging incident beam

Demonstration of multiple beam interference in reflection using the same cavity

Simultaneous observation of multiple beam interference in transmission and in reflection

Curved mirror cavity — radial modes

Demonstration of multiple beam interference in transmission using a cavity with curved mirrors and a single-frequency laser light source

Observation of the intensity distribution associated with a variety of radial (or transverse) modes as a function of cavity tuning

Observation of the cavity transmission associated with radial modes as a function of cavity tuning

Demonstration of the properties of a confocal resonator, i.e., where the radius of curvature of each mirror is equal to the mirror separation

Demonstration of the behavior just below and just above the confocal condition

Optical spectrum analyzer

Demonstration of the use of a confocal cavity for the spectral analysis of single-frequency laser

Demonstration of the use of a confocal cavity for the spectral analysis of multifrequency laser

Optics: Fraunhofer and Fresnel diffraction
Fraunhofer diffraction — adjustable slit

Demonstration of Fraunhofer diffraction by a narrow slit

Demonstration of Fraunhofer diffraction by an adjustable narrow slit

Fraunhofer diffraction — two slits

Demonstration of Fraunhofer diffraction by a single slit

Demonstration of Fraunhofer diffraction by pairs of 150 μm slits with spacings ranging from 150 μm to 2 mm

Fraunhofer diffraction — multiple slits

Demonstration of Fraunhofer diffraction by a single slit

Demonstration of Fraunhofer diffraction by two slits

Demonstration of Fraunhofer diffraction by three slits

Demonstration of Fraunhofer diffraction by four, five, six, seven, eight, nine, and more slits

Demonstration of Fraunhofer diffraction by multiple slits with line spacings of 100 per inch, 200 per inch, 300 per inch, and 2000 per inch

Demonstration of Fraunhofer diffraction by multiple slits as a function of slit orientation

Fraunhofer diffraction — thin wires

Demonstration of Fraunhofer diffraction by a thin wire

Demonstration of Fraunhofer diffraction by thin wires with different diameters

Fraunhofer diffraction — rectangular aperture

Demonstration of Fraunhofer diffraction by a fixed rectangular aperture

Demonstration of Fraunhofer diffraction by an adjustable rectangular aperture

Fraunhofer diffraction — circular apertures

Demonstration of Fraunhofer diffraction by a circular aperture

Demonstration of Fraunhofer diffraction by circular apertures with different diameters

Fraunhofer diffraction — crossed multiple slits

Demonstration of Fraunhofer diffraction by fixed crossed multiple slits

Demonstration of Fraunhofer diffraction by crossed multiple slits as a function of the relative orientation of the slits

Fresnel diffraction — adjustable slit

Demonstration of Fresnel diffraction by a fixed slit

Demonstration of Fresnel diffraction by an adjustable slit

Observation of the transition from Fresnel to Fraunhofer diffraction using an adjustable slit

Fresnel diffraction — circular apertures

Demonstration of Fresnel diffraction by a circular aperture using a spatially filtered laser source

Demonstration of Fresnel diffraction by circular apertures with different diameters

Demonstration of Fresnel diffraction by a circular aperture as a function of source distance

Optics: propagation in optical fibers
Single mode fiber

Demonstration of a single mode fiber and light coupling into the fiber

Demonstration of single mode transmission

Demonstration of the effect of stress and bends applied to fiber showing light expelled by fiber

Demonstration of the effect of bends and stress on single mode transmission

Multi-mode fiber

Demonstration of light transmission through a multimode fiber, showing a variety of transverse modes

Demonstration of the effect of input alignment changes on transverse modes

Demonstration of the effect of fiber bends and stresses on transverse modes

Demonstration of single mode behavior in a multimode fiber using fiber bends to eliminate higher order transverse modes

Polarization in a single mode fiber

Demonstration of single mode propagation in an optical fiber

Demonstration of the state of polarization of the light exiting the fiber as a function of stress and bends applied to the fiber