Световая эффективность светодиодных источников белого излучения

When creating the lighting systems of various types an estimate of the luminous efficacy of semiconductor white light sources is a relevant issue. A preliminary analysis shows that two types of light emitting diodes (LEDs) can be used as such sources: photo-luminescent LEDs and sets (clusters) of quasi-monochromatic LEDs. Manufacturers show the luminous efficacy of photo-luminescent LEDs in the technical documentation.The goal is to elaborate a calculation technique to estimate the luminous efficacy of LED “white” light sources as the sets (clusters) of quasi-monochromatic LEDs. This goal is set because there is no such a technique. In addition, the analysis of practical problems shows that the LED clusters are of interest not only as the white light sources, but also as the light sources with color control.The paper presents the technique to calculate the luminous efficacy based on the relationship between photometric and color parameters as applied to the sets of quasi-monochromatic sources. Gives the calculation technique and relationships for the luminous efficacy of “white” clusters consisting of 2, 3, and an arbitrary number n of quasi-monochromatic LEDs. These results were used to conduct comparative analysis of the luminous efficacy of photo-luminescent LEDs and LED clusters as the sources of "white" light. It is shown that the luminous efficacy of LED clusters corresponds to the maximum efficacy of modern photo-luminescent LEDs. It is substantiated that LED clusters have a number of advantages over photo-luminescent LEDs, such as capability to correct chromaticity of white light (its color temperature), to control chromaticity, and to use LED clusters in color dynamic systems, especially for color displays with a wide color gamut. The relationships obtained can be used in power calculations of LED-based lighting systems.При создании осветительных систем различного типа актуальным вопросом является оценка световой эффективности полупроводниковых источников белого излучения. Проведённый предварительный анализ показал, что в качестве таких источников могут использоваться светоизлучающие диоды (СИД) двух типов: фотолюминесцентные СИД и наборы (кластеры) СИД квазимонохроматического излучения. Световая эффективность фотолюминесцентных СИД указывается производителями в технической документации.Целью работы является разработка методики оценки световой эффективности полупроводниковых источников «белого» излучения в виде наборов (кластеров) СИД квазимонохроматического излучения. Данная цель определяется тем, что такие методики практически отсутствуют. Кроме того, анализ практических задач показал, что светодиодные кластеры представляют интерес не только как источники белого излучения, но и как источники излучения с возможностью перестройки цветности излучения.В настоящей статье представлена методика расчёта световой эффективности оптического излучения на основе связи фотометрических и колориметрических параметров применительно к набору источников монохроматических излучений. Предложена методика и получены соотношения для определения световой эффективности «белых» кластеров, состоящих из двух, трёх и произвольного числа СИД квазимонохроматического излучения. Эти результаты использованы для сравнительного анализа световой эффективности фотолюминесцентных и кластерных СИД как источников «белого» излучения. Показано, что световая эффективность кластерных СИД соответствует максимальным значениям эффективности современных фотолюминесцентных СИД. Обоснованы преимущества кластерных СИД по сравнению с фотолюминесцентными, которыми является возможность коррекции цветности белого излучения (его цветовой температуры), управления цветностью излучения и применения кластеров в цветодинамических системах, в частности, для цветных дисплеев с широким цветовым охватом. Полученные соотношения могут использоваться в энергетических расчетах осветительных систем на основе СИД

Quantitative super-resolution solid immersion microscopy via refractive index profile reconstruction

Solid Immersion (SI) microscopy is a modern imaging modality that overcomes the Abbe diffraction limit and offers novel applications in various branches of visible, infrared, terahertz, and millimeter-wave optics. Despite the widespread use, SI microscopy usually results in qualitative imaging. Indeed, it presents only the raw distributions (in the image plane) of the backscattered field intensity, while unlocking the information about the physical properties of an imaged object, such as its complex refractive index (RI) distribution, requires resolving the inverse problem and remains a daunting task. In this paper, a method for resolving the SI microscopy inverse problem is developed, capable of reconstructing the RI distribution at the object imaging plane with subwavelength spatial resolution, while performing only intensity measurements. The sample RI is retrieved via minimization of the error function that characterizes discrepancy between the experimental data and the predictions of analytical model. This model incorporates all the key features of the electromagnetic-wave interaction with the SI lens and an imaged object, including contributions of the evanescent and ordinary-reflected waves, as well as effects of light polarization and wide beam aperture. The model is verified numerically, using the finite-element frequency-domain method, and experimentally, using the in-house reflection-mode continuous-wave terahertz SI microscope. Spatial distributions of the terahertz RIs of different low-absorbing optical materials and highly absorbing biological objects were studied and compared to a priori known data to demonstrate the potential of the novel SI microscopy modality. Given the linear nature of the Maxwell’s equations, the developed method can be applied for subwavelength-resolution SI microscopy at other spectral ranges

Non-destructive methods of diagnostics of nitrogen provision of plants by optoelectronic system of plants monitoring

The article is devoted to solving actual scientific-technical and economic challenges - development of non-destructive method of diagnostics of the domestic varieties of plants, implemented by appropriate optoelectronic system. Substantiated general method [1] of the spectral analysis of the pigment composition of photosynthetic vegetation unit. Proved dependence of concentration of mineral substances in a plant from the pigment composition of photosynthetic vegetation unit. The character of the link between the nitrogen provision status of plants, depending of the spectral reflectance curves and of the value of the main vegetative index of the method - NDVI. Experimentally obtained the dependence of the spectral reflectance index of photosynthetic unit of vegetation from the concentrations of nitrogen fertilizers in the soil for selected plant species. During experimental studies confirmed the theoretical position on the possibility of using non-destructive optical methods for determining nitrogen provision of plants. To implement the proposed method is selected optoelectronic monitoring system according to the level of development of agricultural machinery