An optical pulse measuring method measuring an optical pulse generated from a pulse light source is provided. The method includes: splitting the optical pulse and then focusing them at a measuring point, so as to generate gas plasma by the autocorrelation of the split optical pulses; receiving the sound signal from the gas plasma and generate a plasma sound signal; and using the plasma sound signal to calculate the characteristics of the optical pulse. A measuring device is also provided.

The ability to communicate with a specific subject at a prescribed location who lacks any communications equipment opens up many intriguing possibilities. Communications across noisy rooms, hail and warn applications, and localized communications directed at only the intended recipient are a few possibilities. We disclose and show localized acoustic communications, which we call photoacoustic communications, with a listener at long standoff distances using a modulated laser transmitted toward the receiver's ear. The optically encoded information is converted into acoustic messages via the photoacoustic effect. The photoacoustic conversion of the optical information into an audible signal occurs via the absorption of the light by ambient water vapor in the near area of the receiver's ear followed by airborne acoustic transmission to the ear. The recipient requires no external communications equipment to receive audible messages.

Disclosed by the present disclosure is a photoacoustic dual-mode imaging probe, which comprises an optical fiber, a transducer and a housing; the optical fiber and the transducer are at least partially housed at the interior of the housing, and a light outlet of the optical fiber and a front end of the transducer are both located at an head end of the photoacoustic dual-mode imaging probe; the optical fiber is used to emit laser pulses; and the transducer is used to transmit and receive ultrasound signals. The photoacoustic dual-mode imaging probe uses the housing to wrap the optical fiber and the transducer inside the housing, such that the three become a whole, thereby being easy to clean and disinfect, being convenient to hold, having strong human-computer interaction performance, and eliminating the use of a coupling pad.

An underwater acoustic deception system deceives a sensor installed on a threat existing in or on water by acoustic effect in order to protect ships from the threat. The underwater acoustic deception system is provided with a control device, a laser oscillator and emission optical system. The control device determines a focusing position to focus a laser beam (50) in water in order to generate bubbles (70) at a desired position with a desired scale and emission parameters of the laser beam (50). The laser oscillator generates the laser beam (50) configured to focus in water and generate bubbles. The emission optical system emits the generated laser beam (50) to the focusing position. The underwater acoustic deception system deceives an arbitrary sensor existing in the water by acoustic effect of the bubbles (70) on the surroundings.

A sensor device, including a sensor having a sound transducer to emit sonic waves and convert received sonic waves to electrical signals. A sensor evaluation unit carries out surrounding-area monitoring during a normal operation of the sensor, by evaluating electrical signals of the sound transducer. During a monitoring mode of the sensor, a monitoring unit of the sensor device measures an impedance of the sound transducer for different excitation frequencies of excitation signals produced with a signal generator of the sensor device. The sensor device includes a first and a second signal path, which are each connected to the sound transducer and are connectable to the signal generator. To reset the sensor from normal operation to the monitoring mode, a first control unit of the sensor device is configured to decouple the signal generator from the first signal path and to connect it to the second signal path.

A system for measuring conditions in a wellbore includes tubing extending into the wellbore. A high power laser having a power greater than 1 kW is operable to deliver a light to a first fiber optic cable. The first fiber optic cable extends axially along a fist surface portion of the tubing and has at least one signal generation gauge located at a predetermined location for producing a generated acoustic signal that propagates outward from the generation gauge and through the tubing. A second fiber optic cable extends axially along a second surface portion of the tubing and is operable to receive a resulting signal of the generated acoustic signal so that wellbore parameters proximate to the predetermined location can be determined. The second fiber optic cable is spaced apart from the first fiber optic cable and is operable to transmit data of the resulting signal to a receiver.

A phonon parametric oscillator is provided. The phonon parametric oscillator comprises a laser for periodically emitting brief optical pulses (IL), an assembly for generating acoustic pulses (IA) and a medium for coupling the acoustic pulses to an object (O), the assembly for generating acoustic pulses comprising an entrance face, an exit face, a conversion medium for converting the brief optical pulses into acoustic pulses and a propagation medium for propagating said acoustic pulses, the entrance and exit faces being reflective to the acoustic pulses, the propagation medium having a defined thickness, the exit face making contact with the coupling medium. In the phonon parametric oscillator according to the invention, the round-trip time of an acoustic pulse due to reflection from the entrance and exit faces, is equal to the emission period () of the laser, so that the reflected acoustic pulse is in phase with the following acoustic pulse.

The ability to communicate with a specific subject at a prescribed location who lacks any communications equipment opens up many intriguing possibilities. Communications across noisy rooms, hail and warn applications, and localized communications directed at only the intended recipient are a few possibilities. We disclose and show localized acoustic communications, which we call photoacoustic communications, with a listener at long standoff distances using a modulated laser transmitted toward the receiver's ear. The optically encoded information is converted into acoustic messages via the photoacoustic effect. The photoacoustic conversion of the optical information into an audible signal occurs via the absorption of the light by ambient water vapor in the near area of the receiver's ear followed by airborne acoustic transmission to the ear. The recipient requires no external communications equipment to receive audible messages.

Disclosed herein is a photoacoustic tomography (PAT) probe to direct light to various regions within the tissue of interest to improve image quality and remove cumbersome artifacts at their source. Particularly, a rotating PAT probe and method of using thereof to improve the photoacoustic penetration depth and signal to noise ratio in biological samples. Signal intensity at region of interest is increased by fine-tuning the fiber orientation with respect to the ultrasound transducer. Additional PA filter is used to prevent in vivo probe-skin artifacts.

To provide an ultrasonic transmission instrument that can uniformly transmit ultrasonic waves in each direction around the instrument, even when the instrument is made of a material through which the ultrasonic waves cannot be transmitted. In an ultrasonic transmission instrument according to the invention, a light transmission member is disposed at an emission end of an optical waveguide, and an outer peripheral member covers an outer periphery of the light transmission member and is made of a light absorbing material.