The bending of a laser beam in a medium with a density and refractive index gradient in the same direction has been described previously. When a transparent container is half filled with a salt or sugar solution and an equal amount of water is floated on top of it, then diffusion will create a concentration gradient from top to bottom. A laser…

There seems to be no reasonable way to measure the thickness of a narrow-mouth glass bottle. One can measure the outer and inner diameters of the mouth with a ruler or a pair of calipers and then calculate the thickness. However, this measurement might be interfered with by the threads at the mouth. Furthermore, it is uncertain whether the…

An experiment is described to introduce students to an important class of solid-state reactions while reinforcing concepts of titration by using a pH meter and a powder X-ray diffractometer. The experiment was successful in teaching students the abstract concepts of solid-state structure and diffraction by applying the diffraction concepts learned…

Over the history of the study of visual perception there has been great success at discovering countless visual illusions. There has been less success in organizing the overwhelming variety of illusions into empirical generalizations (much less explaining them all via a unifying theory). Here, this article shows that it is possible to…

We present an experiment, well adapted for students of introductory optics courses, for the visualization of the impact of spherical aberration in the point spread function of imaging systems. The demonstrations are based on the analogy between the point-spread function of spherically aberrated systems, and the defocused patterns of 1D slit-like…

This note presents and discusses a class of real integrals involving a hyperbolic function by means of complex integration. An integral representation is obtained which appears in several fields of physics, including statistical mechanics, condensed matter and quantum optics and more in the so called dispersion relations.

A phase-shift interferometry experiment is proposed, working on a Twyman-Green optical configuration with additional polarization components. A guideline is provided to modern phase-shift interferometry, using concepts and laboratory equipment at the level of undergraduate optics courses. (Contains 5 figures.)

The refraction of a light ray by a homogeneous, isotropic and non-dispersive transparent material half-space in uniform rectilinear motion is investigated theoretically. The approach is an amalgamation of the original Fermat's principle and the fact that an isotropic optical medium at rest becomes optically anisotropic in a frame where the medium…

The study describes and compares the size-dependent optical properties of organic dyes with those of semiconductor nanocrystals or quantum dots (QDs). The analysis shows that mixtures of QDs contain emission colors that are sum of the individual QD components.

Volume phase holographic (VPH) optical elements have made a major contribution to Raman spectroscopy by providing notch filters, and VPH gratings that provide remarkable performance advantages over previous technologies. Holographic notch filters have eliminated Rayleigh scattered laser light from single monochromators, thereby contributing to the…

The interactive nature of computer simulation allows students to develop a deeper understanding of the laws of charged particle optics. Here, the use of commercially available optical design programs is described as a tool to aid in solving charged particle optics problems. We describe simple and practical demonstrations of basic electrostatic…

A proper presentation of scientific discoveries may allow science teachers to eliminate certain myths about the nature of science, which originate from an uncertainty among scholars about what constitutes a discovery. It is shown that a disagreement on this matter originates from a confusion of the act of discovery with response to it. It is…

The pages of "The Physics Teacher" have featured several clever designs for homemade diffraction gratings using a variety of materials--cloth, lithographic film, wire, compact discs, parts of aerosol spray cans, and pseudoliquids and pseudosolids. A different and inexpensive method I use to make low-resolution diffraction gratings takes advantage…

Perspective is a rich area for mathematical work, and one that should be accessible to many students, since it is based on the everyday experience of viewing the 3D world directly and through familiar 2D representations (drawings, photographs, images on a television or cinema screen, etc). A nice feature of perspective tasks is that they can be…