Abstract: The present disclosure belongs to the field of photoacoustic signal detection, and specifically relates to a quantum-enhanced all-optical photoacoustic signal detection device and method. The problem of low sensitivity of photoacoustic signals based on interference measurement is solved, and high-sensitivity detection of photoacoustic signals generated by living organisms including human bodies can be achieved. A degenerate optical parametric oscillator based on a first-type phase matching crystals is used for preparing a vacuum squeezed state light field, a coherent control technology is used for locking the squeezed angle to obtain the quadrature phase vacuum squeezed state, the prepared quadrature phase vacuum squeezed state light field is injected into the vacuum channel of a Michelson interferometer, and a balanced homodyne detection mode is used for achieving detection of the quantum-enhanced photoacoustic signals.

Abstract: Embodiments of the present disclosure provide a datum selection method for minimizing hole position errors in group hole machining of large components, comprising: 1) determining a type of a computer numerical control (CNC) machine tool and establishing a topological structure of the CNC machine tool; 2) establishing a theoretical postural model of a tool center point during a motion; 3) establishing a hole position error model; 4) establishing an average error model of hole positions in group hole machining; and 5) obtaining a machining datum for group holes of corresponding components. For the skeleton and skinned group hole machining of aircraft components, different principles of datum selection are provided respectively, which can effectively improve the positional accuracy of the skeleton or skinned group hole machining, at the same time provides a more scientific and reasonable approach for the datum selection in group hole machining of large components.

Abstract: An integral optical resonant cavity for frequency conversion is provided. The integral optical resonant cavity includes: a housing, a cavity-length adjustment device, a temperature control device and a nonlinear crystal provided in the temperature control device; a first plano-concave mirror and a second plano-concave mirror included in the cavity-length adjustment device and a nonlinear crystal form the optical resonant cavity; and light passes through the first plano-concave mirror, the nonlinear crystal and the second plano-concave mirror sequentially. The stability of the length of the optical resonant cavity is improved through an integral design thereof, and the stability of the temperature of the nonlinear crystal in the integral optical resonant cavity is improved through the temperature control device, thereby stably controlling relative phases between light fields for the frequency conversion in the resonant cavity.

Abstract: A method is disclosed for generating a sub-nanosecond pulse laser, using a voltage-increased type electro-optical Q-switched laser. The method includes: applying a square wave driving signal on a Pockels cell in an electro-optical Q-switched laser by using a Q-switch driver module, where the peak voltage of the square wave driving signal is higher than the quarter-wave voltage of the Pockels cell; and performing, by controlling the loss related to the electro-optical Q switch with a voltage of the driving signal increasing from 0 to the peak voltage, a change of the working state of the electro-optical Q switch from a switched-off state to a switched-on state, and then to a partially-switched-on state. The intracavity laser is exhausted within a quite short time, so that the pulse width of the laser is shortened, to implement sub-nanosecond operation of a pulse laser.

Abstract: CT imaging systems and methods thereof are disclosed. A common CT scanning is performed on an object to obtain a common CT imaging. An area of interest is determined from the image. A CT scanning is performed on the area of interest under a plurality of energy windows by a photon counter detector. A high resolution image of the area of interest is reconstructed. The discrimination of energy spectrum is higher and the result so obtained is more stable by using a photon counter detector to collect photon count projection data of a plurality of energy windows and thus it may be decomposed into a plurality of basis functions.

Abstract: CT imaging systems and methods thereof are disclosed. A common CT scanning is performed on an object to obtain a common CT imaging. An area of interest is determined from the image. A CT scanning is performed on the area of interest under a plurality of energy windows by a photon counter detector. A high resolution image of the area of interest is reconstructed. The discrimination of energy spectrum is higher and the result so obtained is more stable by using a photon counter detector to collect photon count projection data of a plurality of energy windows and thus it may be decomposed into a plurality of basis functions.