New Kind Of Light Source Research Articles

THERMAL ENHANCEMENTS OF A LED BASED AUTOMOTIVE HEADLAMP

Light Emitting Diode (LED) is a new kind of light source that is quickly being used into automotive lighting systems. In recent years, there have been increased expectations placed on vehicle headlamps, including that they not only be fully functional, affordable, and long-lasting, but also stylish, energy-efficient, and environmentally friendly. Since LED light sources are long-lasting, highly efficient, and energy-efficient, small in size, etc., they are frequently utilized in headlamps, turn signals, brake lights, position lights, etc. and will soon dominate the automotive light source industry. Although it has a greater energy conversion efficiency, the thermal management of LED headlamps is still a problem. In this research, the response surface method is used to optimize the heatsink designs for LED automotive headlamp module. The finite element (FE) approach and numerical simulation are used to model the test samples temperature distribution. Then, in order to maximize the heatsink potential for thermal dissipation, we tested different types of material, and used the response surface method. The LED headlamp hot spots decrease by 2 to 8 degrees when the heat sinks thickness, fin spacing, and height are optimized and decrease by 7.64 degrees when the heat sink and PCB substrate are made of 6063 aluminum alloy and AlN, respectively.

Corneal Damage Effects Induced by a 770-2,500 nm Supercontinuum Light Source.

Widespread applications of supercontinuum (SC) source lead to the possibility of ocular damages. However, the corneal damage effects induced by SC have not been explored before. The objectives of this study are to determine the rabbit corneal injury threshold for SC radiation and to examine whether the existing safety guidelines and standards are suitable for the hazard evaluation of this new kind of light source. A series of experiments was conducted in the New Zealand white rabbit model to determine the corneal damage thresholds induced by a 770-2,500 nm SC source, with a corneal 1/e beam diameter of 0.37 mm. Through slit-lamp biomicroscope, optical coherence tomography (OCT), and histopathology the corneal damage characteristics at the threshold level were revealed. By employing the action spectra determined through the analysis of safety guidelines and standards, the damage thresholds for SC source could be compared with the corresponding exposure limits. The determined damage thresholds given in terms of the peak radiant exposure for exposure durations of 2.0 and 10.0 seconds were 2.1 × 103 and 7.4 × 103 J/cm2 , respectively. At threshold level, corneal damages involved the epithelium and the shallower stroma, and no obvious changes could be found in the deep stroma, Descemet's membrane, and endothelium. The exposure limits for the anterior parts of the eye in the wavelength range of 700-1,200 nm are overly conservative. The obtained results contribute to the knowledge base for the hazard evaluation of SC source. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Tapered-fiber-enabled high-power, high-spectral-purity random fiber lasing.

Random distributed feedback Raman fiber laser is a new kind of light source that can be applied to generate a high-power laser. In this Letter, we report on a high-power, high-spectral-purity random Raman fiber laser based on tapered fiber, in which the four-wave mixing (FWM) effect has been sufficiently suppressed. By choosing an appropriate tapered fiber length, we achieve a maximum random laser output of 491W, and the spectral purity can reach to as high as 94%. We carefully compare the influence of different tapered fiber lengths and splicing patterns on the FWM effect by the cutting-back method and lateral-offset splicing. The results show that the transverse modes dispersion is responsible for the appearance of FWM by compensating the phase mismatch. It is believed that a kilowatt-level random laser can be obtained by further optimizing the parameters of tapered fiber.

A survey of lasers at the birth of holography

The 50th anniversary of the first hologram made with laser light is an appropriate time to shine some light on the lasers that made it possible. Dubbed "a solution looking for a problem", the laser emerged from industrial research labs as a new kind of light source for any application requiring coherence. Immediately commercialized by both start-up and well-established corporations, lasers sold in their first year of production left much to be desired but made a good first impression. Their second year of production saw technical improvements that met the requirements for practical holography, and by the end of 1963 were good enough to make holograms of three dimensional, deep and diffuse imagery. Mostly obsolete by the end of the 1960s, very few of the Kennedy era lasers have survived. This survey is intended to identify and celebrate them, so more may be preserved as they are found, to be admired in the future.

Iterative Model for Simulating Light Intensity Variation of LED

As a new kind of light source, LED light source has found wide application in many fields, especially in automotive lamp light source with the rise of luminous efficacy. The paper puts forward an iterative model, which approximates the light intensity variation of LED by adding up a series of the luminous flux of sub light sources with uniform light intensity, and accurately reflects the attenuation feature of LED light intensity. As long as the tracing ray is sufficient, the calculation error will be very small, and the result ideal, thus making it suitable for engineering application.

Study of 660 nm laser-induced photoluminescence of chlorophyll-a and its applications

Based on the phenomenon of chlorophyll a photoluminescence, this paper introduces a new method to measure the chlorophyll a content, using 660nm laser diode as a new kind of light source to stimulate fluorescence as well as combining a fiber and spectrum technique. We analyze the characteristics of laser-induced fluorescence spectrum of chlorophyll a and then put forward the new method using two parameters, the relative fluorescence intensity and fluorescence intensity ratio F685/F735, to measure the chlorophyll a content in the water and green leaves respectively. The experimental results indicate that it is completely feasible to give a visual judgment for chlorophyll a content, according to the fluorescence emission spectrum of chlorophyll a. Subsequently, it is verified by three kinds of typical applications. All of these provide a new kind of light source to develop the chlorophyll a fluorometry and further give a technical foundation of on-spot monitoring the chlorophyll a content in the ocean or in green leaves.

Treatment of palmoplantar psoriasis with monochromatic excimer light (308-nm) versus cream PUVA

Palmoplantar psoriasis is a chronic disease, which is very resistant to treatment and often leads to severe disabilities. Photochemotherapy employing psoralens combined with UVA irradiation (PUVA) is a well-accepted therapy for palmoplantar psoriasis. Its topical application (bath PUVA; cream PUVA) avoids the typical side effects of orally applied psoralens. We compared the efficacy of cream PUVA therapy with monochromatic excimer light therapy, a treatment modality employing 308-nm UVB radiation generated by a new kind of light source. Ten patients with psoriasis of the palms and soles were randomly assigned to receive cream PUVA on one side and 308-nm UVB on the contralateral side. Based on the psoriasis area and severity index (PASI) score, clinical assessment was carried out before and 5 weeks after the beginning of the study. At the end of the treatment period both test groups showed a remarkable PASI score reduction (308-nm UVB, 63.57%; cream PUVA, 64.64%). No relevant adverse effects were observed, except for mild irritation in a few patients. After a 12-week follow-up, a relapse of the disease was only observed in one patient. Thus, mono-chromatic excimer light cleared palmoplantar psoriasis as rapidly as cream PUVA. In contrast to cream PUVA, monochromatic excimer light therapy is not associated with prior drug application. This might lead to a lower incidence of adverse reactions and better compliance. Therefore, monochromatic excimer light therapy seems to be a useful new therapeutic option for palmoplantar psoriasis.