Described is a way for an amateur to build a mercury-vapor ion laser which was devised by Dean Morelli. Morelli's laser emits bright pulses of green light and dimmer pulses of red-orange light and is the first gaseous-ion laser. (Author/DS)

Provides information regarding underwater vision. Includes a discussion of optically important interfaces, increased eye size of organisms at greater depths, visual peculiarities regarding the habitat of the coastal environment, and various pigment visual systems. (CS)

Describes the photodiode array and the electrical connections necessary for it. Also shows a few of the optical demonstration possibilities-shadowgraphs for measuring small objects, interference and diffraction effects, angular resolution of an optical system, and a simple spectrometer. (Author/DS)

Described is the phasor method of superposition of waves. The intensity pattern from a system of microwave sources is calculated point by point on a plane corresponding to a film emulsion, and then printed and directly converted to a hologram for 3-cm microwaves. Calculations, construction, and viewing of holograms are included. (Author/DS)

Describes details of the construction of a simple compact schlieren experimental setup as an instructional aid. This new optical method is easy to apply, noninterfering, nondestructive, free from inertia, and can produce instantaneous records of transient phenomena, and is comparatively inexpensive. (Author/SK)

Discusses how holography can be used as part of undergraduate physics laboratories. The authors propose a single beam technique of holography, which will reduce the recording scheme as well as relax the isolation requirements. (HM)

Describes a method to form on a large fixed screen the succession of the diffraction patterns on the different infinity. This method is designed to be used in a college physics course. (HM)

Using a photon-counting technique, finds the angular distribution of emitted and detected power and the total radiated power of an arbitrary moving source, and uses the technique to verify the predicted effect of the earth's motion through the cosmic blackbody radiation. (Author/GA)

Investigates the "photographic" appearance of a cube moving at relativistic speeds, and shows that it depends upon whether the camera is held fixed with the optic axis perpendicular to the direction of motion or panned to follow the cube as it moves. (Author/GA)

Investigates the effect of the nonuniform irradiance across a laser beam on diffraction of the beam, specifically the Fraunhofer diffraction of a laser beam with a Gaussian irradiance profile as it passes through a circular aperture. (GA)

This simple and inexpensive experiment is an illustration of the physical concepts of interaction between light and surface tension waves, and provides a new method of measuring surface tension. (Author/GA)

Discusses the principal of formation of shadows, and the speed involved with their appearance or disappearance. (GA)

Describes the following: use and construction of a lens-pinhole spatial filter assembly to produce expanded beams; how to modify a unilab V. L. F. oscillator to give variable frequencies between .1 Hz and 10 Hz; to use Crookes radiometer quantitatively; and an externally located, movable probe for plasma physics experiments, using conventional…

Describes a simple method to measure the size of the Earth to an accuracy of order of magnitude 10 percent. The procedure involves finding the time interval between two sunsets, a sunset observed at sea level while lying down, and a sunset viewed at eye height after standing up. (GA)

Discusses several aspects of Fraunhofer diffraction patterns from apertures illuminated by diverging light. Develops a generalization to apertures of arbitrary shape which shows that the sizes of the pattern are related by a simple scale factor. Uses the Abbe theory of image formation by diffraction to discuss the intensity of illumination of the…