In order to further improve the rotation accuracy of ultraprecision roundness measuring instruments, a new single-step rotation error separation technique (SEST) is proposed to accurately separate instrument spindle rotation error and workpiece roundness error. This is done by first selecting an appropriate rotation angle and rotating the workpiece through a small angle with respect to the instrument spindle, and then measuring mixed errors A(n) and B(n) including workpiece error g(θ) and spindle rotation error z(θ) before and after rotation, and finally achieving accurate separation of z(θ) and g(θ) through Fast Fourier Transformation and harmonic analysis. Theoretical analysis and simulation results indicate that the signals in the harmonic range 1–100 upr can be totally separated from the wide range of harmonics measured when rotation angle error Δα < 0.01° is achieved by optimizing the rotation angle α. In comparison with the multi-step separation technique commonly used in roundness measuring instruments, SEST can be used to totally eliminate any harmonics singularity in the range of 1–100 upr and to make the error separation system very simple, shorten the separation process and reduce the separation time.

The magnetism of zirconium and hafnium dichalcogenides by hole doping is studied by using first principles calculations.

We report an efficient continuous-wave self-Raman laser at 1176 nm based on a 20-mm-long composite YVO 4 /Nd:YVO 4 /YVO 4 crystal and pumped by a wavelength-locked 878.9 nm diode laser. A maximum output power of 5.3 W is achieved at a pump power of 26 W, corresponding to an optical conversion efficiency of 20% and a slope efficiency of 21%. The Raman threshold for the diode pump power was only 0.92 W. The results reveal that in-band pumping by a wavelength-locked diode laser significantly enhances output power and efficiency of self-Raman lasers by virtue of improved pump absorption and relieved thermal loading.

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