A photofliudic audio receiver for producing sound directly from light modulated at audio frequencies and amplifying the sound to deliver uniform frequency response over a wide audio frequency range, utilizing only fluidic and thermal devices. It includes a photoacoustic cell for converting the modulated light signal to an acoustic signal, and at least one laminar proportional amplifier (LPA) for amplifying the acoustic signal to provide the sound output of the receiver. Each LPA has a rising frequency response over the wide audio frequency range, to thus offset the inherent falling frequency response of the photoacoustic cell. The receiver may have several amplifying stages, each stage including several LPA's connected in parallel. The receiver may also include acoustic highpass filters connected in series with the LPA inputs or outputs to accentuate the rising frequency response of the LPA's. The sound output of the receiver can be fed to acoustic terminating devices such as headphones or an exponential horn.
An acoustic detection device having a parabolic dish antenna for gathering ound waves and providing a first stage of amplification, an exponential horn located at the focus of the parabolic dish antenna for further acoustic amplification, a fluidic gainblock for a final stage of amplification, and acoustic earphones for listening. Either a hand operated latex bulb or a mechanical pump is used to pressurize a plastic fluid storage container that is used to supply fluid to the fluidic gainblock. Within the fluidic gainblock are four or more staged laminar proportional amplifiers having a bandwidth of 0 to 4,000 Hz.
A pneumatic actuator comprises a cell through which a normally laminar flow of air passes between an inlet and an outlet to provide, in the outlet, an output pressure. The cell includes an electro-acoustic transducer, for example a piezo-electric element arranged, in response to an oscillating electrical signal, to produce an acoustic signal that disturbs the laminar flow whereby at least some of the air exhausts from the cell via one or more exhaust ports and the output pressure falls. The difference in the output pressures may be used to control a pneumatic device optionally via a pneumatic amplifier. The electrical signal is produced by an opto-electrical transducer to which optical control signals are transmitted, for example along a fibre optic cable.
A method of providing near simultaneous night vision and communication including directing a narrow voice modulated IR laser beam at a distant receiver/demodulator during communication periods, causing the IR laser beam to diverge substantially during scene viewing periods, other than the data communication periods, for illuminating a darkened scene which includes the laser beam receiver, and viewing the darkened scene with an IR viewing device.
An enhanced output opto-fluidic device includes three plates which together bound a number of passages including an interaction passage, an inlet channel including which opens into one of such ends, and two outlet channels which open into the other end of the interaction passage at symmetrically arranged outlet regions. Fluid is caused to flow through the inlet channel into the interaction passage to form a jet stream that flows toward the outlet regions. After the flow of the fluid through the inlet channel has been intentionally disturbed by heating a transversely offset light-absorbing zone of the inlet channel by a light beam with attendant heating of the fluid flowing past such zone and initial transverse deflection of the jet stream, the extent of such deflection is enhanced by supplying additional amounts of the fluid to symmetrically situated lateral locations of the interaction passage so that the jet stream permits more of the fluid to enter the interaction passage from that of the locations from which it deflected away than from the other locations with attendant additional deflection of the jet stream.
A fluidic sound amplification system couples successive laminar proportional amplifiers through acoustic radiation between output and input horns to avoid the propagation of null offset signals. A second approach to obviating DC null bias in a fluidic sound amplification system comprises splitting the input signal, effecting a selected time delay on a portion of the signal such that the bandpass frequencies and dead zones or cancellation frequencies respectively of the amplified signals are 180.degree. out of phase and combine to produce a near uniform frequency response. A third approach is to use multiple parallel elements in each stage of amplification in such a manner that mechanical errors cancel each other out.
