Amplitude Subtraction Research Articles

Influence of coherence and misalignment on the complex amplitude addition and subtraction by holographic Fourier transformation

General results are given for the influence of coherence and misalignment on the complex amplitude addition and subtraction by holographic Fourier transformation. For the method of Gaboret al. we have investigated the effects of longitudinal and transverse misalignment of the recording material between the first and second exposure. A method for complex addition and subtraction of Fourier transforms is investigated also.

Experimental results on the tidal resonance effect of the liquid core

Abstract Molodenskii's theory on the resonance effect of the liquid core predicts anomalous amplitudes in the diurnal spectrum for earth tide registrations of gravity and tilt. A two years recording of an Askania gravimeter at Kiel University has been analysed using three different numerical methods: harmonic analysis (least squares method), gliding harmonic analysis, and Fourier spectral analysis. Because of difficulties in resolving tidal waves near the resonance frequency, efforts were made towards improving the Fourier spectral analysis by successive subtraction of high amplitudes in the Fourier spectrum. The resonance of the liquid core has been observed with a high degree of confidence thereby supporting Molodenskii's model calculations.

Optical Image Synthesis (Complex Amplitude Addition and Subtraction) in Real Time by a Diffraction-Grating Interferometric Method

A coherent processing system for obtaining complex addition of two or more patterns in real time is described. In this system, a sinusoidal diffraction grating is used in the spatial-frequency plane. The input patterns to be added are displayed symmetrically about the optical axis in the object plane. The complex amplitude addition appears in th zero-order location in the output plane. Complex amplitude subtraction may be obtained by adding a 180° phase plate behind one of the input patterns. Displacing the sinusoidal diffraction grating by half a line pitch is also shown to change the performance of the system from addition to subtraction for two input functions, without the need for a phase plate. Experimental verification of the performance is presented. Analysis of the system for two input patterns is first given, then extended to the complex addition of multiple inputs.

The structure of haemoglobin - V. Imidazole-methaemoglobin: a further check of the signs

The crystals are apparently orthorhombic; their unit-cell dimensions and the intensities of the 00lreflexions suggest a structure closely related to monoclinic methaemoglobin. Each structure appears to contain the same molecular layers parallel to (001), but in the monoclinic form the molecules are tilted the same way in each layer, while in the new form the tilt is alternately left and right in successive layers. Precession pictures show an interesting sequence of sharp and diffuse layer lines, those with certain indiceshcontaining streaks parallel to c*. In other layer lines the spots are broadened in varying degrees. The amplitudes of theh0lreflexions are related to the molecular Fourier transform described in previous papers of this series. Each value ofF(h0l) is compounded from the sum or the difference of the amplitude at two points on the transform having the co-ordinatesha* 0Ic* andha* 0l̄c*. The rules for addition and subtraction of amplitudes follow a simple scheme which is related to the sequence of sharp and diffuse layers. The scheme accounts for all observed values ofF(h0l), a reliability factor of 0. 21 being obtained. This correlation provides an independent check for the sequence of signs along certain layer lines of the transform. A preliminary analysis of the structure is made, and molecules in neighbouring layers are shown to be displaced by 11. 2 Å in theadirection.