Conventional eddy-current sensors have the advantages of being contactless and having high bandwidth and high sensitivity. They are widely used in micro-displacement measurement, micro-angle measurement, and rotational speed measurement. However, they are based on the principle of impedance measurement, so the influence of temperature drift on sensor accuracy is difficult to overcome. A differential digital demodulation eddy current sensor system was designed to reduce the influence of temperature drift on the output accuracy of the eddy current sensor. The differential sensor probe was used to eliminate common-mode interference caused by temperature, and the differential analog carrier signal was digitized by a high-speed ADC. In the FPGA, the amplitude information is resolved using the double correlation demodulation method. The main sources of system errors were determined, and a test device was designed using a laser autocollimator. Tests were conducted to measure various aspects of sensor performance. Testing showed the following metrics for the differential digital demodulation eddy current sensor: nonlinearity 0.68% in the range of ±2.5 mm, resolution 760 nm, maximum bandwidth 25 kHz, and significant suppression in the temperature drift compared to analog demodulation methods. The tests show that the sensor has high precision, low temperature drift and great flexibility, and it can instead of conventional sensors in applications with large temperature variability.
With the emergence of high-performance infrared detectors and the latest progress in grating manufacturing technology, high-resolution and high-sensitivity infrared spectrometers provide new methods for application to many fields, including astronomy and remote sensing detection. Spectral detection has attracted considerable attention due to its advantages of noncontact and stability. To obtain the detailed features of the missile’s tail flame spectrum, traditional plane reflection gratings are used as the main dispersive element; however, the instrument’s volume will increase with increasing resolution, which is not conducive to remote sensing detection from airborne platforms. Such spectrometers cannot meet high-resolution spectroscopy requirements. To address this problem, this paper proposes an immersion echelle spectrometer combined with a three-mirror astigmatism optical system. High resolution and compact size were achieved. In this paper, a small high-resolution infrared echelle spectrometer optical system was created by combining an off-axis three-mirror anti-astigmatism system, a Littrow structure, and a concave grating Wadsworth imaging device. The optical system operated in the 3.7–4.8 μm band; the echelle grating worked under quasi-Littrow conditions, while the concave grating was used for auxiliary dispersion to separate overlapping orders. The resolution of the optical system in the entire working band was 23,000–45,000. The optical plane size of the spectrometer was around 360 mm × 165 mm. The results show that the Mid-IR echelle spectrometer achieved high spectral resolution, better than 0.25 cm−1, meeting missile tail flame detection requirements. This device has the potential for real-time long-range target detection when warheads are destroyed. While this study focuses on the mid-wave infrared band, its approach can also be extended to other infrared bands.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.