Measurement error in hydrostatic leveling system due to temperature effect and their reduction method.

Temperature is a crucial factor influencing the accuracy of the hydrostatic leveling system (HLS), necessitating a temperature compensation test for HLS. This paper investigates HLS temperature compensation through theoretical correction and experimental verification. The influence of temperature on the accuracy of hydrostatic level products is determined through temperature tests on 34 hydrostatic level products. The optimal temperature compensation formula is derived using the non-linear curve fitting method. The HLS is enhanced with a temperature compensation algorithm and temperature sensor, resulting in a new, high-precision, and high-stability hydrostatic leveling product with temperature compensation. Experimental findings reveal that the stability of the improved hydrostatic leveling product exceeds 30% compared to products on the market and surpasses 70% compared to the original products.

Ultrasensitive deafness gene DNA hybridization detection employing a fiber optic Mach-Zehnder interferometer: Enabled by a black phosphorus nanointerface.

The rapid and efficient detection of deafness gene DNA plays an important role in the clinical diagnosis of deafness diseases. This study demonstrates the ultrasensitive detection of complementary DNA (cDNA) by employing a nanointerface-sensitized fiber optic biosensor. The sensor consists of SMF-TNCF-MMF-SMF (abbreviated as STMS) structure with lateral offset. Besides, it is functionalized with a nanointerface of black phosphorus (BP) to enhance the light-matter interaction and eventually improve the sensing performances. Relying on this nanointerface-sensitized sensor, we successfully realize the in-situ detection of cDNA at concentrations ranging from 1 pM to 1 µM, with a sensitivity of 0.719 nm/lgM. The limit of detection (LOD) is as low as 0.24 pM, which is at least two orders of magnitude lower than those of existing methods. The sensor exhibits the advantages of simple operation, fast response, label-free measurement, excellent repeatability, and high selectivity. Our contribution suggests a convenient approach for deafness gene DNA detection and can be extended for general ultra-low concentration DNA detection applications.

Femtosecond laser written ultra-weak Fabry-Perot array for distributed absolute temperature profile sensing with high spatial resolution.

In this paper, high spatial-resolution distributed temperature sensing has been realized based on a femtosecond laser written ultra-weak Fabry-Perot Array (FPA). 50 identical Fabry-Perot cavities are fabricated in a 10 mm long optical fiber by femtosecond laser point-by-point written technology, and the corresponding spatial resolution is as high as 200 µm. Besides, by employing the total phase demodulation method, the optical path lengths (OPLs) in the ultra-weak FPA are successively demodulated based on the Rayleigh backscattering signal recorded by an optical frequency domain reflectometry (OFDR), and therefore the absolute temperature values instead of the relative ones can be obtained. When compared with the conventional single mode fiber-based OFDR, the proposed ultra-weak FPA presents both higher spatial resolution and lower temperature sensing uncertainty (0.25 °C) benefiting from the periodically enhanced Rayleigh backscattering. Furthermore, the experiments also confirm that the ultra-weak FPA can be applied for absolute temperature field profile sensing with large temperature gradient, which is particularly suitable for high-resolution temperature measurement of miniature devices.