Continuous Dynamic Rotation Measurements Using a Compact Cold Atom Gyroscope

We present an experimental demonstration of the rotation measurement using a compact cold atom gyroscope. Atom interference fringes are observed in the stationary frame and the rotating frame, respectively. The phase shift and contrast of the interference fringe are experimentally investigated. The results show that the contrast of the interference fringe is well held when the platform is rotated, and the phase shift of the interference fringe is linearly proportional to the rotation rate of the platform. The long-term stability, which is evaluated by the overlapped Allan deviation, is 8.5 × 10^-6 rad/s over the integrating time of 1000s.

Enhancement of the angular rotation measurement sensitivity based on SU(2)and SU(1,1) interferometers

We investigate the sensitivity of the angular rotation measurement with the method of homodyne detection in SU(2) and SU(1,1) interferometers by employing orbital angular momentum(OAM). By combining a coherent beam with a vacuum beam in an SU(2) interferometer, we get the sensitivity of the angular rotation measurement as 1/(2N^(1/2)l). We can surpass the limit of the angular rotation measurement in an SU(1,1) interferometer by combining a coherent beam with a vacuum beam or a squeezed vacuum beam when the probe beam has OAM. Without injection, the sensitivity can reach 1/(2N^(1/2)l). In addition, by employing another construction of an SU(1,1) interferometer where the pump beam has OAM, with the same injection of an SU(1,1) interferometer, the sensitivity of the angular rotation measurement can be improved by a factor of 2, reaching 1/(4Nl). The results confirm the potential of this technology for precision measurements in angular rotation measurements.

Noise reduction and signal to noise ratio improvement in magneto-optical polarization rotation measurement

The measurement of an extremely small magneto-optical polarization rotation angle with high sensitivity is integral to many scientific and technological applications. In this Letter, we have presented a technique based on Faraday modulation combined with the optical differential method to measure an extremely small polari- zation rotation angle with high sensitivity. The theoretical and experimental results show that common mode noise is reduced appreciably and signal to noise ratio is enhanced. The effectiveness of this technique has been demonstrated by measuring the Verdet constant of terbium gallium garnet glass and measuring the small polari- zation rotation angle. A sensitivity of enhancement of one order of magnitude has been achieved using differ- ential detection based on Faraday modulation.

Rotational Population Measurement of Ultracold 85Rb^133Cs Molecules in the Lowest Vibrational Ground State

We measure the rotational populations of ultracold SS Rbla3 Cs molecules in the lowest vibrational ground state by a depletion spectroscopy and quantify the molecular production rate based on the measurement of single ion signal area. The SSRb133Cs molecules in the X1∑＋（v = 0） are formed from the short-range （2）^3П0＋（V = 10, J = 0） molecular state. A home-made external-cavity diode laser is used as the depletion laser to measure the rotational populations of the formed molecules. Based on the determination of single ion signal, the production rates of molecules in the J=0 and J = 2 rotational levels are derived to be 4800mole/s and 7200mole/s, respectively. The resolution and quantification of molecules in rotational states are facilitative for the manipulation of rotational quantum state of ultracold molecules.

Measurement of the Plasma Rotation Velocity by Using Visible Spectrum on HL-1M Mokamak

The plasma rotation velocity were measured in HL-1M with Doppler shifts of CⅢ、 C Ⅱ、 O Ⅱ and H. line by a SKD high resolution spectrometer. The effects .of density' hydrogen pellet injection and carbon impurities injected by laser-blow-off on toroidal(V) and poloidal (Vθ)rotation velocity have been observed. The Vθ measured from H. line is only half of that from C Ⅱ impurity line.

MEASUREMENT OF ANGULAR VIBRATION AMPLITUDE BY ACTIVELY BLURRED IMAGES

A novel motion-blur-based method for measuring the angular amplitude of a high-frequency rotational vibration is schemed. The proposed approach combines the active vision concept and the mechanism of motion-from-blur, generates motion blur on the image plane actively by extending exposure time, and utilizes the motion blur information in polar images to estimate the angular amplitude of a high-frequency rotational vibration. This method obtains the analytical results of the angular vibration amplitude from the geometric moments of a motion blurred polar image and an unblurred image for reference. Experimental results are provided to validate the presented scheme.

High Resolution Clinometers for Measurement of Roll Error Motion of a Precision Linear Slide

This paper proposes a new method for measurement of the roll error motion of a slide table in a precision linear slide. The proposed method utilizes a pair of clinometers in the production process of a precision linear slide, where the roll error motion measurement will be carried out repeatedly to confirm whether the surface form errors of slide guideways in the linear slide are su ciently corrected by hand scraping process. In the proposed method, one of the clinometers is mounted on the slide table, while the other is placed on a vibration isolation table, on which the precision linear slide is mounted, so that influences of external disturbances can be cancelled. An experimental setup is built on a vibration isolation table, and some experiments are carried out to verify the feasibility of the proposed method.

Current measurement method based on magneto-optic rotation effect

Aiming at the approximate measurement of magnetic rotation angle in optical current sensor based on light intensity detection mode,this paper proposes a current measurement method based on triangular constant transformation to reconstruct magnetic rotation angle,so as to avoid the large current measurement error caused by the approximate measurement of the magnetic rotation angle.By extracting the direct current(DC)component and the alternating current(AC)component of the light intensity signal detected by the photoelectric detector(PD),the sine signal containing the magnetic rotation angle is directly obtained by dividing the two components,and then the triangular identity transformation method is used to linearly demodulate the magnetic rotation angle and reconstruct the current waveform.The experimental results show that the relative error of current measurement does not exceed 1.40%in the current range of 0.05—0.50 A,which is less than the approximate linear measurement(ALM)method,and the magnetic rotation angle and the current have a good linear relationship.

Rotation speed measurement of moving particles in a CFB riser

This paper presents a study on measuring rotation speed of moving glass beads with an average diameter of 500 p.m in a pilot-scale circulating fluidized bed （CFB） riser with a high-speed digital imaging system. Two methods have been developed to calculate particle rotation speed from the particle images. The first method consists of a fully automated algorithm based on cross-correlation of gray distribution of particle images for particles whose rotation axes are （nearly） perpendicular to the imaging plane, and the second method calculates the speed of particle rotation by identifying its rotation axis using two or more characteristic points on its surface. The reliability of the two methods is verified by using a small sphere with known speed and direction of rotation. The first method is shown to be capable of measuring accurately the rotation speed for the particle with a rotation axis （nearly） perpendicular to the imaging plane and filtering off other particles using an appropriate threshold of correlation coefficient. The second method is shown to be capable of yielding both the speed and direction of particle rotation, with a measurement error of less than 10%. Results of both methods on real glass beads in a CFB riser are compared against each other.

Simultaneous measurement of vibration amplitude and rotation angle based on a single-channel laser self-mixing interferometer

Based on a single-channel laser self-mixing interferometcr, we present a new silnultaneous measurement of the vibration amplitude and tile rotation angle of objects that both affect the power spectrum containing two peaks of the interferometer signals. The fitted results indicate that the curve of the peak frequency versus the vibration amplitude follows a linear distribution, and the curve of the difference of the two-peak power values versus the angle follows a Gaussian distribution. A vibration amplitude with an error less than 3.0% and a rotation angle with an error less than 11.7% are calculated from the fitted results.

Observation of tiny polarization rotation rate in total internal reflection via weak measurements

In this paper,we examine the tiny polarization rotation effect in total internal reflection due to the spin–orbit interaction of light.We find that the tiny polarization rotation rate will induce a geometric phase gradient,which can be regarded as the physical origin of photonic spin Hall effect.We demonstrate that the spin-dependent splitting in position space is related to the polarization rotation in momentum space,while the spin-dependent splitting in momentum space is attributed to the polarization rotation in position space.Furthermore,we introduce a quantum weak measurement to determine the tiny polarization rotation rate.The rotation rate in momentum space is obtained with 118 nm,which manifests itself as a spatial shift,and the rotation rate in position space is achieved with 38 μrad∕λ,which manifests itself as an angular shift.The investigation of the polarization rotation characteristics will provide insights into the photonic spin Hall effect and will enable us to better understand the spin–orbit interaction of light.

Identification of Protein Coding Regions of Rice Genes Using Alternative Spectral Rotation Measure and Linear Discriminant Analysis

An improved method, called Alternative Spectral Rotation (ASR) measure, for predicting protein coding regions in rice DNA has been developed. The method is based on the Spectral Rotation (SR) measure proposed by Kotlar and Lavner, and its accuracy is higher than that of the SR measure and the Spectral Content (SC) measure proposed by Tiwari et al. In order to increase the identifying accuracy, we chose three di?erent coding characters, namely the asymmetric, purine, and stop-codon variables as parameters, and an approving result was presented by the method of Linear Discriminant Analysis (LDA).

Novel laser Doppler tachometer

In order to improve the accuracy and universality of the rotational speed measurement,an instantaneous rotational speed measurement method based on laser Doppler technology is proposed.The composition and working principle of the new system are discussed in detail.Theoretical and experimental results show that the new rotational speed measurement system belongs to the non-contact method,which eliminates the quantization error of the contact method and greatly improves the applicability and accuracy.Compared to the commonly used method,the measurement accuracy of the new rotational speed measurement system will not be affected by the system’s installation angle deviation,and it does not need to measure the radius of the rotating body,so the influence of the radius fluctuation of the rotating body on the measurement accuracy can be avoided while outputting the rotational speed in real time.The relative error of the rotational speed measurement is less than 0.06%(1σ).