E. E. Tynan

Laser enhanced electroplating and maskless pattern generation

Maskless plating has been achieved through a new technique that utilizes a cw or pulsed laser, focused onto an electrode in an electroplating bath. In the region of optical absorption on the cathode, plating enhancement rates on the order of 103 occur for optical power densities on the order of 104 W/cm2. Laser scanning produces a plating pattern along the scanning path. A qualitative theory based on convective mass transport is used to explain the results.

Method and apparatus for focusing elastic waves converted from thermal energy

Pulsed light is applied through a plano concave lens to a thin metal film, which is evaporated on the concave side of the lens. The lens, which is formed of a high thermally insulating material such as glass, for example, and the film are disposed within a liquid such as water, for example. The pulsed light is absorbed by the metal film, which converts the thermal energy produced by the pulsed light into elastic waves in the form of acoustic waves and simultaneously focuses the acoustic waves on an object within the water at a selected focal plane. The metal film is as thin as possible, consistent with complete absorption of the light energy by the metal film, so as to utilize the high thermal expansion coefficient of the water.

Increased laser tunability by acidification of organic dyes

From an investigation of the fluorescence and laser tunability of 7-N-methylamino-4, 6-dimethylcoumarin, we have found a convenient means of extending the laser bandwidth and tunability by acidification of the solution. The general applicability of this method applied to other organic dyes is also discussed.

Temperature dependence of transverse planar voltages in laser‐irradiated Pt and Pd films

The temperature dependence of laser‐induced transverse voltages in Pt and Pd films has been investigated in the range ∼25–300 °K. When the data are normalized to a constant average film temperature gradient, a close similarity is found between the normalized values and bulk thermopower data throughout the temperature range. These results suggest a possible model requiring only scalar thermopower coefficients.

Phonon‐induced planar voltages in thin metallic films

We have irradiated slant‐angle‐deposited metallic films on sapphire substrates with pulses of incoherent phonons and observed voltages in the plane of the sample. These voltages are very similar in character to those previously observed using laser irradiation as the excitation source. The new data prove unequivocally that these as well as our previously observed voltages in metal films are purely thermal in origin, consistent with a thermoelectric model.

Microscope stage sample holder capable of temperature variation between 30 and 800 K

A novel vacuum sample holder is described for use with an optical microscope. The sample stage temperature can be made to vary from ∼ 30 to 800 K. Electrical feedthroughs together with an optical window provide convenient features for use in a wide variety of experiments. Data for optically induced transverse thermoelectric voltages of a Pd film as a function of temperature are presented.

A Rotating Sample Holder Using Flexible Fiber Optics for the Excitation and Detection of Photoluminescence at Liquid Helium Temperatures

We describe a sample holder useful for the study of the angular dependence of photoluminescence at liquid helium temperatures. The system is characterized by a high collection efficiency and is particularly well suited to situations where there is only vertical access to the experimental space.