Spatial frequency modulated single detector imaging

Abstract

This thesis presents images of absorbing and fluorescent objects captured by modulating a time varying spatial frequency to an illumination beam. The modulator produces a field intensity with a linear increase in temporal modulation frequency across its spatial extent. The linear temporal modulation is preserved after square law integration over the area of the detector and present in its electronic signal. Recording the temporal signal out of the detector with analog to digital converter and then Fourier transforming recovers the profile of the spatial field intensity distribution on the detector. This imaging modality offers the possibility of relatively simple and high speed imaging of objects with an single element detector. The modulator can be produced at low cost by printing a mask onto a clear CD-ROM substrate. The theory developed explains how the parameters of the modulator and optical system relate to the resolution and number of points in the electrical image. Numerical simulations are used to explore the optical limits of the electrical image in the presence of optical aberrations. Experimental results verify theoretical relations and images are captured of a Air Force test pattern and prepared fluorescent patterns

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