Joseph F. Stephany

A theory of 1/f noise

Universal 1/f noise is shown to originate from the variations in the initial velocities of conduction electrons after collisions with defects. Defect atoms, after being struck by conduction electrons, recoil and form an impacted mass of lattice atoms. Conduction electrons emitted after a collision have an average initial velocity which steadily decreases as the impacted mass builds up. It is shown that this process yields a noise spectrum of the form f−n where n is in the vicinity of one and has an amplitude given by the Hooge empirical formula. Variations from the Hooge result are discussed. The model described applies to all semiconductors and metals.

Keystone compensation for image storage systems

Certain types of optical storage devices are preferentially read out with off-axis illumination. This method, however, produces keystohing of the projected image, which is a serious disadvantage. In this paper a double Keystone system is analyzed in which a controlled distortion is introduced by the input system to compensate for the distortion by the projection system. The necessary equations to solve the system are presented in terms of a single parameter which makes a simple solution practical.

Origin of 1/f noise

A source of 1/f noise fitting experimental data is derived from the assumption that the units of the autocorrelation function must be those of power. This assumption results in a complex autocorrelation function. A source of 1/f noise can then be derived from an increase in the observed electron velocity resulting from the action of the applied electronic field on the lattice atoms. This results in the following expression for the 1/f noise power spectrum: S (ω) = (8I20R0/N0) × (m−/m+)1/2(1/ω), where m− and m+ are the effective masses of the electron and lattice atoms, respectively.

Origin of 1/f noise—Part III: A source of magnetically generated 1/f noise

An interaction between noise‐generating mechanisms and a uniformly moving magnetic field is derived and the conditions under which it may be observed are discussed. It is found that the effect of a uniform field generating a force in the direction of the conduction electrons is to create a new noise source which is linear with the current flowing in a conductor and which possesses a 1/f frequency dependence. The observation of this magnetically generated noise source has the theoretical interest of testing a theory of 1/f noise previously published, as well as providing a means of reducing ordinary 1/f noise to zero.

Bimorph optical beam deflector.

A simple piezoceramic optical beam deflector was constructed in this laboratory for feasibility studies. When the results were compared with those obtained for similar systems by other authors, a significant increase in the deflection sensitivity was noted. The configuration and dimensions of the beam deflector are shown in Fig. 1. The bimorph strip is a sandwich configuration consisting of a metal foil approximately 0.1 mm thick to which two PZT elements, about 0.15 mm thick, are bonded. One end of the strip is epoxied into a slot in a large lead block, and a mirror made from a gold-coated 1-cm square microscope cover glass is epoxied to the other end of the strip. The weight of the bimorph strip was 1.955 g and of the mirror 0.036 g. The amount of beam deflection expected for a given applied voltage can be calculated by noting that the PZT elements will expand on one side of the metal foil and contract on the other side by an amount equal to

Matrix transform optical calculus for generalized linear dielectric media.

Described here is an optical calculus developed to meet the practical need for ray tracing in new classes of imaging devices such as liquid crystals. The calculus is intended for computer programming and uses a method of matrix transform to eliminate redundancy, thereby reducing computer programming and execution time. The calculus, a coherent calculus of the Jones type, is also useful in interpreting the interaction between the components of a light wave when retardation, optical activity, and isotropic nonisotropic linear and circular dichroism are all present simultaneously.