The analysis and design of deep-sea lighting field based on spectral transfer function

Due to the attenuation of light in water, the deep-sea optical imaging system needs an active lighting system to provide the light source. However, because of the nonlinearity of light attenuation in spatial dimension and spectral dimension, the deep-sea lighting differs from terrestrial lighting. In order to quantitatively analyze and design deep-sea lighting system, we proposed a precise deep-sea lighting field simulation model and design method based on spectral transfer function. Firstly, with the analysis of deep-sea lighting-imaging process, the spectral transfer function in lighting field was analyzed and the deep-sea lighting model was built. Then, the platform used to study light attenuation was set up and the attenuation characteristics of light in water were derived. Moreover, the deep-sea lighting field simulation model was built with the computer program. Finally, the experiment platform for testing the underwater lighting field was set up in test pool. The experimental results show that the deep-sea lighting field computational model is accurate. In addition, the optimal deep-sea lighting system design was proposed. This study provides the theoretical basis and experimental data for the design of a deep-sea lighting system which has far-reaching significance for improving the efficiency of deep-sea scientific research

Analysis of Stray Light and Enhancement of SNR in DMD-Based Spectrometers

Due to advantages such as the high efficiency of light utilization, small volume, and vibration resistance, digital micro-mirror device (DMD)-based spectrometers are widely used in ocean investigations, mountain surveys, and other field science research. In order to eliminate the stray light caused by DMDs, the stray light in DMD-based spectrometers was first measured and analyzed. Then, the stray light was classified into wavelength-related components and wavelength-unrelated components. Moreover, the noise caused by the stray light was analyzed from the perspective of encoding equation, and the de-noising decoding equation was deduced. The results showed that the accuracy range of absorbance was enhanced from [0, 1.9] to [0, 3.1] in single-stripe mode and the accuracy range of absorbance was enhanced from [0, 3.8] to [0, 6.3] in Hadamard transform (HT) multiple-stripe mode. A conclusion can be drawn that the de-noising strategy is feasible and effective for enhancing the SNR in DMD-based spectrometers

Freeform lens collimating spectrum-folded Hadamard transform near-infrared spectrometer

A novel Hadamard transform spectrometer collimated by a freeform lens has been designed, which doubles the working spectral range while the spectral resolution is maintained. The freeform lens is designed to redistribute the broadband spectra of the source from 800 nm to 2400 nm into two collimated beams with different wavelengths and different tilting angles, to achieve the folding of spectra on the digital micro-mirror devices (DMD). It is constructed by solving two partial differential equations. The grating diffraction efficiency of the two split beams are more uniform and higher compared with the traditional method. The simulation results show that the bandwidth of the spectrometer is doubled and the spectral resolution is better than 10 nm. The optical system becomes more compact, and the energy efficiency is improved by 11.98% by folding the spectra with one freeform lens and one grating

The observation and prediction of constant quality factors of LnAlO_3 doped Ba_(6-3x)Ln_(8+2x)Ti_(18)O_(54)(Ln = Nd, Sm, La) ceramics

Usually, the quality factor of a binary-phase ceramic will increase if the volume molar ratio of the high quality factor component increases, and vice versa. However, the quality factor of Ba_(6-3x)Ln_(8+2x)Ti_(18)O_(54) (Ln = Nd, Sm, La) ceramics (~ 2500 at 4 GHz) keeps a constant as the volume molar ratio of LnAlO_3 (~ 9000 at 7 GHz) increases. While previous studies reported the importance of microstructure variation, here by fitting the dielectric constant, via definition we derived a quality factor calculation formula that can precisely determine the quality factor variation versus the volume molar ratio, which is of great significance for guiding the ceramic manufacturing

The observation and prediction of constant quality factors of LnAlO_3 doped Ba_(6-3x)Ln_(8+2x)Ti_(18)O_(54)(Ln = Nd, Sm, La) ceramics

Usually, the quality factor of a binary-phase ceramic will increase if the volume molar ratio of the high quality factor component increases, and vice versa. However, the quality factor of Ba_(6-3x)Ln_(8+2x)Ti_(18)O_(54) (Ln = Nd, Sm, La) ceramics (~ 2500 at 4 GHz) keeps a constant as the volume molar ratio of LnAlO_3 (~ 9000 at 7 GHz) increases. While previous studies reported the importance of microstructure variation, here by fitting the dielectric constant, via definition we derived a quality factor calculation formula that can precisely determine the quality factor variation versus the volume molar ratio, which is of great significance for guiding the ceramic manufacturing

Neuroprotective Roles of l-Cysteine in Attenuating Early Brain Injury and Improving Synaptic Density via the CBS/H2S Pathway Following Subarachnoid Hemorrhage in Rats

l-Cysteine is a semi-essential amino acid and substrate for cystathionine-β-synthase (CBS) in the central nervous system. We previously reported that NaHS, an H2S donor, significantly alleviated brain damage after subarachnoid hemorrhage (SAH) in rats. However, the potential therapeutic value of l-cysteine and the molecular mechanism supporting these beneficial effects have not been determined. This study was designed to investigate whether l-cysteine could attenuate early brain injury following SAH and improve synaptic function by releasing endogenous H2S. Male Wistar rats were subjected to SAH induced by cisterna magna blood injection, and l-cysteine was intracerebroventricularly administered 30 min after SAH induction. Treatment with l-cysteine stimulated CBS activity in the prefrontal cortex (PFC) and H2S production. Moreover, l-cysteine treatment significantly ameliorated brain edema, improved neurobehavioral function, and attenuated neuronal cell death in the PFC; these effects were associated with a decrease in the Bax/Bcl-2 ratio and the suppression of caspase-3 activation 48 h after SAH. Furthermore, l-cysteine treatment activated the CREB–brain-derived neurotrophic factor (BDNF) pathway and intensified synaptic density by regulating synapse proteins 48 h after SAH. Importantly, all the beneficial effects of l-cysteine in SAH were abrogated by amino-oxyacetic acid, a CBS inhibitor. Based on these findings, l-cysteine may play a neuroprotective role in SAH by inhibiting cell apoptosis, upregulating CREB–BDNF expression, and promoting synaptic structure via the CBS/H2S pathway

The deep-sea camera with three detectors based on triple-prism

The deep-sea photogrammetry is an important means of deep-sea exploration. Due to the attenuation of light in water, deep-sea camera systems need deep-sea lamps to provide the light source, which consume lots of energy. So the light utilization efficiency of deep-sea optical camera affects the load capacity and operation capacity of deep-sea platforms. In addition, due to the non-linearity of light attenuation in different wavelength, the deep-sea optical images generally suffer from color deviation with tending to be blue and green, which leads to the decline of operation efficiency and the increase of scientific research cost in deep-sea exploration. In order to improve the light utilization efficiency and enhance the color restoration of deep-sea camera, we proposed, designed and developed a deep-sea camera with three detectors based on triple-prism (TD&TP-DSC) for the first time. In this camera system, three detectors combined with triple-prism aimed to improve the light utilization efficiency, and the coatings on the triple-prism were designed for gating waveband to improve the color restoration. With carrying out a series of experiments in water tank, water pool, Qiandao Lake and the South China Sea, the low-light performance and color restoration of TD&TP-DSC were certified. The experimental result showed that TD&TP-DSC had advantages over the common deep-sea camera, which provided enlightenment for the development of new generation deep-sea camera system