Abstract: The present invention discloses a method for measuring a spatial rotation angle of an object, comprising steps of: controlling projection of probe light onto an object whose rotation angle is to be measured; controlling a balance homodyne detector, by which the probe light reflected or transmitted by the object whose rotation angle is to be measured is detected to obtain light parameters of the reflected or transmitted probe light; and calculating a rotation angle of the object whose rotation angle is to be measured, according to the light parameters detected by the balance homodyne detector. The device of the present invention is simple, easy to operate, and high in practicality. The measurement precision is high, and measurements of a rotation angle beyond the SNL (shot noise limit) can be realized. The present invention can be applied in high-tech fields such as precise manufacturing, spatial remote-sensing and bioimaging.

Abstract: The disclosure relates to a quartz-enhanced photoacoustic spectroscopy gas detection apparatus and method based on beat effect. Provided is a quartz-enhanced photoacoustic spectroscopy gas detection apparatus based on beat effect, comprising a photoacoustic signal detection module, a gas chamber, a light source module and a data acquisition module. In the present invention, by detecting the beat signal generated by mixing the piezoelectric signal output from the quartz tuning fork with the demodulation signal of the lock-in amplifier, the electrical parameters of the quartz crystal oscillator and the concentration of the gas to be measured can be obtained accurately in a time period on the order of milliseconds.

Abstract: A method for expanding a tuning range of an all-solid-state continuous-wave single-frequency laser is provided. The method includes inserting a nonlinear frequency-doubling crystal into a laser resonant cavity, and converting a part of intra-cavity fundamental-frequency light to frequency-doubled light by the nonlinear frequency-doubling crystal, outputting the generated frequency-doubled light and the fundamental-frequency light together from the laser resonant cavity, and separating the two via a spectroscope. The method also includes splitting a part of the fundamental-frequency light reflected by the spectroscope through an optical beam-splitter, and outputting the remaining part of the fundamental-frequency light as a main laser.

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: The present disclosure provides a device for reducing residual amplitude modulation. The device includes an electro-optic modulation device with three crystals connected in series. The three crystals are the first cubic crystal, an intermediate crystal, and the second cubic crystal respectively. The intermediate crystal is an electro-optic modulating crystal. The intermediate crystal is connected to the high-frequency signal source module. The specification of the intermediate crystal is X mm×Y mm×d mm. The first cubic crystal and the second cubic crystal is connected to both ends of the intermediate crystal in series along the direction of the X axis. The relative dielectric constant of the first cubic crystal and the relative dielectric constant of the second cubic crystal both are equal to the relative dielectric constant of the intermediate crystal. The specification of the first cubic crystal and the specification of the second cubic crystal both are d/2 mm×Y mm×d mm.

Abstract: The present disclosure provides a device for reducing residual amplitude modulation. The device includes an electro-optic modulation device with three crystals connected in series. The three crystals are the first cubic crystal, an intermediate crystal, and the second cubic crystal respectively. The intermediate crystal is an electro-optic modulating crystal. The intermediate crystal is connected to the high-frequency signal source module. The specification of the intermediate crystal is X mm×Y mm×d mm. The first cubic crystal and the second cubic crystal is connected to both ends of the intermediate crystal in series along the direction of the X axis. The relative dielectric constant of the first cubic crystal and the relative dielectric constant of the second cubic crystal both are equal to the relative dielectric constant of the intermediate crystal. The specification of the first cubic crystal and the specification of the second cubic crystal both are d/2 mm×Y mm×d mm.

Abstract: This disclosure relates to a process for selectively extracting Fe(III) ions from an aqueous feedstock containing Fe(III) ions and non-ferric ions. The process comprises contacting the feedstock with an organic phase comprising a phosphonium salt or ammonium salt ionic liquid under liquid-liquid extraction conditions for a time sufficient to allow transfer of at least some of the Fe(III) ions from the feedstock to the organic phase to provide an Fe(III) ion laden organic phase and an Fe(III) depleted feedstock, and separating the Fe(III) ion laden organic phase from the Fe(III) depleted feedstock.

Abstract: A single photons communication method and system is provided. In an example, an information loading module in a transmitting terminal of the single photons communication system may code to-be-sent target information as a corresponding target modulation frequency according to a pre-saved relationship between information and modulation frequency, and perform frequency modulation on a quantum state of communication light generated by a light source by using the target modulation frequency so that the transmitting terminal may send out modulated target communication light.

Abstract: A single photons communication method and system is provided. In an example, an information loading module in a transmitting terminal of the single photons communication system may code to-be-sent target information as a corresponding target modulation frequency according to a pre-saved relationship between information and modulation frequency, and perform frequency modulation on a quantum state of communication light generated by a light source by using the target modulation frequency so that the transmitting terminal may send out modulated target communication light.