Hewlett-packard Company

Brian H Kolner

Moshe Nazarathy

David W Dolfi

A temporal imaging system is presented consisting of a dispersive input path, a phase modulator producing a phase modulation substantially equal to A+Bt.sup.2, and an output dispersive path. This temporal imaging system can be combined with other temporal lenses to image input signals in the same manner that spatial lenses can be used to image light from spatial sources. In particular, this temporal imaging system can be used to expand, compress and or invert input temporal signals.

Temporal imaging with a time lens

An optical time-domain reflectometry (OTDR) system comprises an oscillator, a phase shifter, an amplifier, an optical pulse generator, an integrated electro-optical circuit, a detector, a timer, a converter, and an output device. The OTDR system can be used to determine which surface of a photographic lens is impairing transmissivity the most. When the amplifier is enabled, a signal from the oscillator starts the timer and triggers the pulse generator. The timer is a time-to-digital circuit with analog interpolation. The resulting pulse is transmitted through the integrated electro-optical circuit and into the lens being evaluated. The strongest reflection from the lens is detected and the resulting detection signal stops the timer. The timed duration is expressed by the converter as a distance which can be used to identify the lens surface of interest. The result is displayed and/or stored on the output device. An electrical waveform from the oscillator is conveyed along a transmission line defined by electrodes of the integrated electro-optical circuit. This waveform introduces phase distortion in the optical pulse conveyed along an optical path of the integrated electro-optical circuit. The phase shifter is programmed so that these phase distortions are approximately quadratic over the pulse duration, so that the frequency of the pulse is 'swept' linearly. The integrated electro-optical circuit includes a dispersive grating which introduces time delay as a function of frequency. The combination of sweeping and dispersing results in a pulse which is compressed relative to its original form. The compressed pulse allows more precise identification of the surface causing the strongest reflection so that modern multi-element lenses can be effectively evaluated.

High temporal resolution optical instrument

A sampler that can be used to sample optical or electrical signals, having an improved sensitivity-resolution product compared to conventional samplers. A coded switched electrode modulator has electrodes that produce polarity reversals in an applied voltage signal in accordance with a pseudorandom code having small sidelobes. An optical signal is injected into an optical waveguide that is oriented parallel to the electrodes. When the optical signal is proportional to the coded electrode pattern, the device is used as an electrical sampler. When the applied voltage signal is proportional to the coded electrode pattern, the device is used as an optical sampler.

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Woodside, CA, United States of America

Brian H Kolner