Because of their advantages, including easy tunability of optical and electrical properties by tailoring the molecular structure, flexibility, and compatibility with a low-temperature fabricating ...process, the use of organic semiconductors (OSCs) as active layers has shown strong competitiveness as candidates for use in next-generation high-sensitivity organic photodetectors (OPDs). Infrared (IR) OPDs that are sensitive to illumination at wavelengths higher than 780 nm have been rapidly developed in recent years driven by potential applications such as remote control, night vision, and imaging as well as biomedical monitoring. In this review, after a brief illustration of the mechanisms, we summarize the recent advances in high-performance IR organic photodiodes (OPDIs) and organic phototransistors (OPTs). We will highlight the state-of-the-art protocols for constructing qualified IR OPDs, including new OSCs with excellent photoelectric properties, optimization of active-layer-fabrication processes, and novel device architectures. Thereafter, we will discuss the IR organic light detector as a platform for integrated applications, such as health monitoring, spectrometric analysis, and electronic eyes. This review aims to provide readers with a deeper understanding of the design of future IR OPDs and IR-OPD-based integrated practices.
Active layer engineering, device construction, and integrated applications for infrared organic photodiodes and phototransistors are discussed in this tutorial.
Night vision devices are used for capturing images under low light conditions (<inline-formula> <tex-math notation="LaTeX"> < \,\,10^{-1} </tex-math></inline-formula> lux), which are significantly ...different from images under standard illumination. The night vision devices based on image intensifier tube have power and cost advantages over other night vision devices, such as thermal imaging for short-range surveillance. However, these vision devices suffer from scintillation noise, which makes the resulting images noisy under very low light conditions. This paper presents a comprehensive methodology that uses a consolidated image processing module to improve the performance of low-light images acquired using image-intensifier-based night vision devices. The proposed module is a combination of a two-stage image processing framework. First, a spatio-temporal filter (based on wavelet and recursive frame averaging) is used to minimize inter-frame and intra-frame noise. Then, image enhancement is performed followed by residual noise reduction using a local spatial filter before applying image tone adjustment for display mapping. The results of the proposed module demonstrate performance enhancement of night vision devices under controlled simulated light conditions as well as field conditions. Objective and subjective analysis also reveals that the proposed module can effectively reduce noise and significantly improve visual image quality by 20-30%.
Reptiles are the most morphologically and physiologically diverse tetrapods, and have undergone 300 million years of adaptive evolution. Within the reptilian tetrapods, geckos possess several ...interesting features, including the ability to regenerate autotomized tails and to climb on smooth surfaces. Here we sequence the genome of Gekko japonicus (Schlegel's Japanese Gecko) and investigate genetic elements related to its physiology. We obtain a draft G. japonicus genome sequence of 2.55 Gb and annotated 22,487 genes. Comparative genomic analysis reveals specific gene family expansions or reductions that are associated with the formation of adhesive setae, nocturnal vision and tail regeneration, as well as the diversification of olfactory sensation. The obtained genomic data provide robust genetic evidence of adaptive evolution in reptiles.
Near-infrared light-emitting diodes based on solution-processed semiconductors, such as organics, halide perovskites and colloidal quantum dots, have emerged as a viable technological platform for ...biomedical applications, night vision, surveillance and optical communications. The recently gained increased understanding of the relationship between materials structure and photophysical properties has enabled the design of efficient emitters leading to devices with external quantum efficiencies exceeding 20%. Despite considerable strides made, challenges remain in achieving high radiance, reducing efficiency roll-off and extending operating lifetime. This Review summarizes recent advances on emissive materials synthetic methods and device key attributes that collectively contribute to improved performance of the fabricated light-emitting devices.A summary of recent advances in the near-infrared light-emitting diodes that are fabricated by solution-processed means, with coverage of devices based on organic semiconductors, halide perovskites and colloidal quantum dots.
The perception of halos and other night vision disturbances is a common complaint in clinical practice. Such visual disturbances must be assessed in order to fully characterize each patient's visual ...performance, which is particularly relevant when carrying out a range of daily tasks. Visual problems are usually assessed using achromatic stimuli, yet the stimuli encountered in daily life have very different chromaticities. Hence, it is important to assess the effect of the chromaticity of visual stimuli on night vision disturbances. The aim of this work is to study the influence of the chromaticity of different visual stimuli on night vision disturbances by analyzing straylight and visual discrimination under low-light conditions. For that, we assessed the monocular and binocular visual discrimination of 27 subjects under low illumination using the Halo test. The subjects' visual discrimination was assessed after exposure to different visual stimuli: achromatic, red, green, and blue, both at the monitor's maximum luminance and maintaining the same luminance value for the different visual stimuli. Monocular straylight was also measured for an achromatic, red, green, and blue stimuli. The blue stimulus had the greatest effect on halos in both monocular and binocular conditions. Visual discrimination was similar for the red, green, and achromatic stimuli, but worsened at lower luminance. The greatest influence of straylight was observed for the blue stimulus. In addition, visual discrimination correlated with straylight measurements for achromatic stimuli, wherein greater straylight values correlated with an increased perception of halos and other visual disturbances.
In 1942, Walls described the concept of a ‘nocturnal bottleneck’ in placental mammals, where these species could survive only by avoiding daytime activity during times in which dinosaurs were the ...dominant taxon. Walls based this concept of a longer episode of nocturnality in early eutherian mammals by comparing the visual systems of reptiles, birds and all three extant taxa of the mammalian lineage, namely the monotremes, marsupials (now included in the metatherians) and placentals (included in the eutherians). This review describes the status of what has become known as the nocturnal bottleneck hypothesis, giving an overview of the chronobiological patterns of activity. We review the ecological plausibility that the activity patterns of (early) eutherian mammals were restricted to the night, based on arguments relating to endothermia, energy balance, foraging and predation, taking into account recent palaeontological information. We also assess genes, relating to light detection (visual and non-visual systems) and the photolyase DNA protection system that were lost in the eutherian mammalian lineage. Our conclusion presently is that arguments in favour of the nocturnal bottleneck hypothesis in eutherians prevail.
Night vision technology plays an important role in modern war. In order to reduce the night vision radiance of LCD, a dual‐mode backlight unit (BLU) is used, which includes white LEDs and OGB color ...LEDs. Whether direct or side backlight, this dual‐mode backlight mechanism leads to a big pitch between physically spaced LED array, which makes LCD module thickness increase and hotspots appearance. In this paper, a novel backlight unit with night vision compatible function is designed. The backlight is composed of evenly distributed ORGB 4‐chips‐in‐1 LED array. one 21.5inch direct LCD module was designed and assembled, with thickness of 4.1cm, only 61% of previous generation. The value of NR is 1.934×10−9W/(cm2·SR·nm), meeting the requirements of GJB 1394. The color coordinates of white field are (x0.3087, y0.3403), with the NTSC of 87.7%.
Technological aspects of manufacturing SWIR sensitive detector on the basis of InP/InGaAs/InP photocathode and electron-bombarded CCD are given. Scheme of the digital camera for long distance ...detection is represented. SWIR camera operating mode and properties in case of implementation of impulse laser source are discussed.
Near‐infrared (NIR)‐emitting phosphor materials have been extensively developed for optoelectronic and biomedical applications. Although Cr3+‐activated phosphors have been widely reported, it is ...challenging to achieve ultra‐broad and tunable NIR emission. Here, a new ultra‐broadband NIR‐emitting LiIn2SbO6:Cr3+ phosphor with emission peak at 965 nm and a full‐width at half maximum of 217 nm is reported. Controllable emission tuning from 965 to 892 nm is achieved by chemical unit cosubstitution of Zn2+–Zn2+ for Li+–In3+, which can be ascribed to the upshift of 4T2g energy level due to the strengthened crystal field. Moreover, the emission is greatly enhanced, and the FWHM reaches 235 nm. The as‐prepared luminescent tunable NIR‐emitting phosphors have demonstrated the potential in night‐vision and NIR spectroscopy techniques. This work proves the feasibility of chemical unit cosubstitution strategy in emission tuning of Cr3+‐doped phosphors, which can stimulate further studies on the emission‐tunable NIR‐emitting phosphor materials.
Controllable photoluminescence tuning of ultra‐broadband near‐infrared emitting LiIn2SbO6:Cr3+ phosphor is achieved by chemical unit cosubstitution of Zn2+–Zn2+ for Li+–In3+, and its potential in night‐vision and NIR spectroscopic applications is demonstrated.
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