In this study, we reveal an LED light source model applied in fluorescence microscopes. This optical model is composed of a confocal total internal reflection lens array system (CTLAS) with a nine-LED array. The CTLAS optical system that we designed consists of a total internal reflection (TIR) lens array and a confocal system. The electrical power of the nine-LED array is 7.9 watts, which is lower than traditional light sources, such as the original 120-watt halogen lamps used in fluorescence microscopes (Zeiss, Axio Imager 2). We have successfully applied the CTLAS system to an Axio Imager 2 fluorescence microscope to observe the vascular bundle organization, modified with Cy3 fluorescence molecules, and have found that in the process of system assembly, the fabrication errors of optical lenses could have a critical effect on the CTLAS system. The results of our experiment show that, in order to achieve the same illuminance as that of the halogen lamp, the displacement error tolerances of the lateral x-axis and the longitudinal z-axis must be controlled within 1.3 mm and 1.7 mm, respectively.

Light-emitting diodes (LEDs) have been intensively studied for white-light lighting since their luminous efficacy exceeds 50 lm/W. Currently, the luminous efficacy of an LED light tube/bulb is almost above 100 lm/W. LED solid-state lighting (SSL) has unequivocally become the major light source in general lighting. The fact of high efficiency and other advantages of LED SSL is enough to penetrate all lighting scenarios. However, what people demand from new-generation lighting is not only in energy efficiency but also in lighting quality. Thus, how to make the lighting more user friendly is one of the important issues, and, here, optics is the key point. For making a collection with the discussions of the novel optical design in enhancing lighting efficiency in a more uniform illumination pattern, in higher sharpness for special lighting, in a higher signal-to-noise ratio for communication, in more functions for new applications, etc., this Special Issue of “Advanced LED Solid-State Lighting Optics” focuses on advanced applications in all aspects.

The optical power density in biotissue is an important issue for photobiomodulation (PBM) clinical applications. In our previous study, the maximal dose and the power density distributions of 830 nm lasers under human skin could be exactly calculated and measured. In this work, the laser power density in tissue can be changed by adjusting the focal point of the lens. From the experimental results, it is evident that the power densities on the attached gingiva and the surrounding tissues can be improved. Thus, the dose of a near-infrared (NIR) laser in the target tissue can be increased with a suitable lens. Most importantly, focusing lasers on deeper tissue can avoid any damage to the skin. This study provides a dose optimization method on the target tissue, and the results can be applied to clinical applications, especially laser acupuncture (LA).

This paper describes a compound lens for solar photovoltaic system applications, which is composed of a front aspheric or Fresnel surface and a back array of concave surfaces. In contrast to earlier designs, the proposed method can simultaneously focus and shape sun light into a uniform-square pattern on the solar cell. For a square solar cell, this approach can maximize the solar cell’s opto-electric conversion efficiency by enhancing the concentrated pattern’s uniformity. In this article, the theoretical models of the beam shaping focused lens is derived and then compared with experimental data. The tolerance in assembling the component of the concentrator is also analyzed and the corresponding simulation and experimental results are discussed in detail.

The wave nature of light has been widely demonstrated in a double-slit experiment, which has played a special role in physics teaching. When monochromatic light passes through the double-slit sheet, the diffraction and interference fringes can be observed in the far-field regime. The interference of light causes the beams passing through the two slits to interact with each other, but each slit still retains the diffraction characteristics of a single slit, so the result is a combination of diffraction and interference patterns.

We applied a digital holographic detection technique to detect the scratches on glass surfaces with scattering noise. In the experiment, scratches with widths of 1.67 µm were generated on the front sides of the glass slides, and three different gray levels were painted on the back sides of the glass slides to generate the scattering noise. It demonstrated that the digital holographic detection method can enhance the image contrast of the scratch under high scattering noise. The high defocus tolerance promises a detection process without optical focusing and thus benefits the high-speed automatic optical inspection.