Alan D. Wilson

Characteristic Functions for Time-Average Holography

This paper presents an analysis of the fringes obtained by time-average holographic interferometry of a generalized time-dependent optical phase function. The generalized optical phase function considered is the sum of a series of sinusoidal functions of time having arbitrary amplitudes, frequencies, and relative phases. Characteristic functions are determined for various optical phase functions of interest in time-average holography. In general, the characteristic functions are sums of products of Bessel functions (zero order and higher orders) and exponential phase factors. Rationally and irrationally related frequencies are included in this analysis. An example of vibrating string is considered, to illustrate the application of the results of this paper to objects vibrating at a multitude of frequencies.

X-Ray Lithography: Can It Be Justified

X-Ray lithography: Can it be justified? This is a question which is being asked in many circles today. The answer is, unfortunately, not black or white nor is it easy to determine. However, there are today more serious players in the x-ray field than there were a few years ago and maybe this is an important indicator. In this paper we will try to establish if x-ray lithography can or can not be soundly justified.

Time-Average Holographic Interferometry of a Circular Plate Vibrating Simultaneously in Two Rationally Related Modes*

This paper presents the results of time-average holographic interferometry of a circular metal plate vibrating simultaneously in two unique modes whose frequencies are rationally related. Rational and irrational frequency ratios are presented for comparison. The rational and irrational results differ significantly, and these differences are explained by use of their respective characteristic functions.

Computed Time-Average Holographic Interferometric Fringes of a Circular Plate Vibrating Simultaneously in Two Rationally or Irrationally Related Modes

Numerical evaluation of the characteristic functions of a circular plate vibrating simultaneously in two rationally related modes is presented in the form of computer-generated photographs that are essentially indistinguishable from an actual time-average holographic image. These computed images are obtained by displaying the numerical results on an x, y oscilloscope with z-axis radiance modulation representing fringe irradiance. The effect of changing the relative phases of two rationally related modes is illustrated. Ten computed images are shown; these include fundamental, first higher-order mode (one nodal diameter), irrationally related mode combinations, and rationally related mode combinations with zero through 90° relative phase relations. The computed images are compared with experimentally obtained patterns; good agreement is obtained.

Holographic Interferometry Applied to Motion Studies of Ultrasonic Bonders

case, for an aperture of 100wavelengths; the loss will be smaller for a narrower aperture. It seems that a reasonable upper figure for the contribution to the insertionloss from non-standard irradiation of the ouput transducer may be as much as 1.3 dB. Richardson and Kino (8) used a path-length of 3.05 cm and an aperture of 38 wavelengths. The value of ‘p is reduced by a factor of 38/100,as compared with the value of 1.097 used in Section IV. The insertion loss for 0.1’ tilt is then found to be 0.063 dB, and the insertion loss for misalignment due to a 0.1” divergence of the beam direction from the line joining the center-points of the two transducers is found to be 0.384 dB. From Fig. 3 of Richardson’s and Kino’s paper, a / /and b/l can be taken as 0.2, and bearing in mind that there is little contribution to the loss from the amplitude and phase ripples, Eqns. (17) and (1 8) give a contribution toE of 0.294 dB. The loss due to power in the side lobes is about 0.1 dB, according to observations by Richardson and Kino (8 ) , Kharusi and Farnell (12), and Williamson (private communication). The predicted loss due to inefficiency is thus about 0.85 dB, and the error in the calculation, due to the ideal forms of the various defects that were assumed to simplify the calculation, is probably substantially less than 0.1 dB. The loss observed by Richardson and Kino and not accounted for was about 0.9 _+ 0.2 dB. The agreement is good, and it appears that the effects discussed in this paper can account for the residual observedlosses not previously accounted for. These residual losses do not form part of the transmission coefficient T , but contribute to the efficiency factorE. Only T can be affected by an electrical network connected between the transducer and the load. Thus the residual losses cannot be reduced by changing the parameters of such a circuit.

X-ray lithography in IBM, 1980-1992 the development years

The IBM X-ray lithography research and development program is outlined, from a personal perspective, covering the period from the inception of the program in 1980 through the development of IBMs own storage ring for X-ray production in 1992. The following aspects, among others, are discussed: origins of the program; acquisition of an X-ray port at Brookhaven National Laboratory; masks for X-ray lithography; development of special tooling for X-ray lithography, including a wafer stepper, a precision e-beam X-ray mask writing system, and a superconducting (dipole) electron synchrotron installed in the IBM Advanced Lithography Facility (ALF) in East Fishkill, New York. Key device programs were conducted to increase understanding of the X-ray lithography process and confirm its utility.

Contrast and sensitivity enhancement of resists for high‐resolution lithography

Novolac based resists have received much attention in the submicron device fabrication area because of their high dry etch resistance. In high‐resolution device fabrication requirements novolac resists suffer from a lack in sensitivity and resolution capability. In order to make use of these high‐quality resists, approaches to improve the resolution capability and sensitivity of conventional positive resists have been a major interest of research. Development techniques such as two‐step and spray development techniques to improve resist contrast have been reported, but neither is well characterized and well understood. In this paper, we report an interrupted development technique which enhances the contrast of an electron beam (e‐beam) exposed diazonapthoquinone novolac, AZ‐type resist. As a result of this enhancement, submicron features varying in density can be controlled properly in size and in image profile. The resolution capability of this resist as a single‐layer system is extended to the one‐quart...

Applications of a Holographic Interference Microscope

The holographic microscope has extended the usefulness of holographic interferometry. Without the use of an eyepiece, one is basically concerned with image holography. This is herein considered to include the cases where an object is imaged near, or on, the holographic film plane. The application of image holography for interferometry is described beyond that previously given. Its usefulness for studying small vibrating objects and for real‐time interferometry is demonstrated.

Tungsten Filament Life under Constant‐Current Heating

The time required for the evaporation in a vacuum of a given amount of tungsten from a round tungsten filament heated by constant current is computed and experimentally verified. Tables of time vs normalized wire diameter for initial temperatures between 2000° and 2950°K, in steps of 50°K are presented. The results are valid for any initial wire diameter. The increasing electric field is also computed and tabulated. From the results, the ultimate life of the heated filament can be obtained. For example, at an initial temperature of 2400°K, it is found that when the mass of the wire has diminished 10%, the filament has attained about 98% of its life. The life of the wire under constant‐current conditions is shown to be substantially less than that under constant‐temperature conditions.

Theory of the Parallel Thermocouple

A thermocouple comprised of two elements connected in parallel and connected in series to a third element is analyzed. It is shown that the resulting thermoelectric power of the combined system is a simple function of the thermoelectric power of each and the electrical conductance of the metal conductors. Further, a thermocouple with a certain specific thermoelectric power can be constructed.