Anthony Juliana

Optical recording in the blue using a frequency-doubled diode laser

We have developed a 428 nm blue laser source based on resonator-enhanced frequency doubling of a GaAlAs diode laser and have used this source to demonstrate writing and reading on an MO disk. The power, beam quality, and noise of the blue laser are sufficient for high-density optical recording.

Laser-Addressed Liquid Crystal Projection Displays

A summary is given of recent work on laser-addressed smectic liquid crystal projection displays. Details of the cell construction are given along with some considerations on optimizing contrast ratio. Two display demonstrations are described. The first employs a GaAs laser, has 500x500 picture element capacity, and operates at keyboard-entry speeds. The second demonstration uses an argon laser, has 1024x1024 picture elements, two color capability, and can be written in several seconds.

Thermal generation of confocal domains in a smectic A liquid crystal

The effects of vacuum‐deposited SiOx alignment layers on the thermal generation of focal conic centers in a smectic A liquid crystal were investigated using controlled thermal cycles. Surface defects were found to promote focal conic formation. Focal conic density increases with cooling rate for a given alignment layer, and with the deposition angle of the alignment layer for a fixed cooling rate. An attempt was made to fit these findings to heterogeneous nucleation theory in an effort to better understand the effects of selected thermodynamic properties on the focal conic formation process

Thermal characteristics of matrix‐addressed liquid‐crystal display

The thermal characteristics of matrix‐addressed smectic liquid‐crystal cells are studied using the temperature dependence of the resistance of the heater and detector lines and compared to analytic solutions. The cell behavior is most strongly affected by the thermal properties of the substrate near the liquid crystal if the heater is at that interface. Cell features further away from the heater have a smaller influence. The cell power efficiency improves if the thermal flow through the substrate is reduced relative to the liquid crystal. The cell addressing speed can be increased if the substrate has two layers composed of a thin insulator on a conducting layer. Increasing the insulator thickness improves efficiency but reduces speed.

Apparatus for measuring transient processes during thermomagnetic recording

An apparatus is described for measuring thermal and magnetization dynamics during thermomagnetic writing of information onto magneto‐optic films. By probing various regions of the reversed spot, the spatial dynamics of bit formation can be reconstructed. The spatial resolution of the measurement is better than 1 μ and the intrinsic temporal resolution is 10 nsec. Representative results obtained with a ferrimagnetic and a ferromagnetic sample are included.