Annemarie McCarthy

Bio: Annemarie McCarthy is an academic researcher from Cork Institute of Technology. The author has contributed to research in topics: Ray tracing (graphics) & Adaptive optics. The author has an hindex of 2, co-authored 2 publications receiving 5 citations.

LED-Based Collimating Line-Light Combining Freeform and Fresnel Optics

Abstract: Illumination for line-scan machine vision systems is required to produce a highly asymmetric elliptical beam pattern, to maximize system speed and accuracy. The use of LED emitters with symmetric Lambertian emission patterns is challenging in this context, requiring significant beam reshaping. A design for a collimated line-light, with long working distance, utilizing LEDs with symmetric Lambertian emission patterns, is presented. Using a combination of Fresnel lenses and total internal reflection (TIR) optics, an elliptical beam with a high degree of collimation is achieved. TIR elements are designed based on an adaptation of a freeform lens design method published by Chen et al . [Opt. Express 20, 10 (2012)]. Practical performance of the design is verified experimentally using a prototype unit. In addition, the design is compared, using ray tracing software, to line-lights constructed using commercially available symmetric and elliptical TIR lenses, and its superior performance is confirmed. The optical design described is fully manufacturable and suitable for both small- and large-scale production.

Low-Cost Multispectral Imager

Abstract: A low-cost multispectral imager was built using a multiwavelength LED PCB (light-emitting diode printed circuit board), 3D printed housing, and a monochrome camera, and it was controlled via Nation...

An Alternative Approach for High Uniformity Distribution of Indoor Lighting LED

Abstract: A high accurately theoretical analysis for high uniformity illumination distribution on the ceiling of indoor lighting LED system based on the super-positions is proposed and performed. Starting from the non-uniform illumination distribution of two LED sources, the dependences of the uniformity ratio on the height of the LED source and the length of the ceiling are investigated. The low intensity in the region near the side-wall can be avoided by rotating the LED source with a small angle, but the low uniformity illumination distribution at the center of the ceiling still exists. The aim of this work proposes the alternative design and approach for several configurations and demonstrates that can be obtained high uniform illumination distribution. The redistributed factor of the illumination through the lens is also considered and calculated. The investigation of this work will be a general guideline for designing the high uniform LED indoor lighting systems as well as being valuable materials for the LED lighting manufacturing industry.

Development of UV/Persulfate based laboratory-scale continuous-flow leachate treatment system

Abstract: Stabilized landfill leachates (SLL) contain a high concentration of biorecalcitrant substances. Conventional biological-based water treatment methods are often inefficient in the treatment of SLL. In this study, a laboratory-scale automated continuous flow leachate treatment system was developed to study the feasibility of combining coagulation–flocculation and a sulfate radical-based advanced oxidation process (UV-activated persulfate) in the treatment of SLL. SLL was first treated with coagulation–flocculation. Subsequently, the pre-treated leachate was filtered through a sand filter into an ammonia-stripping tank and a flow-through UV purifier. Ammonia stripping and the UV-activated persulfate advanced oxidation process were performed simultaneously to remove ammonium ions and dissolved organic matter from the pre-treated SLL. The treated SLL was then passed through an anion exchange column for sulfate ion removal. The results showed that this system reduced chemical oxygen demand and total organic carbon concentrations by 91 and 90%, respectively. Further, 68% of ammoniacal nitrogen was removed. The color and turbidity of the SLL were removed entirely, and the system removed 70 to 98% of the metals commonly contained in SLLs. The phytotoxicity and ecotoxicity of the SLL were also largely reduced. The results confirmed that the developed continuous flow leachate treatment system could efficiently reduce the color, chemical oxygen demand, total organic carbon, metals, ammoniacal nitrogen, and the toxicity of SLL.

Spectral Diffractive Lenses for Measuring a Modified Red Edge Simple Ratio Index and a Water Band Index.

Abstract: We propose a novel type of spectral diffractive lenses that operate in the ±1-st diffraction orders. Such spectral lenses generate a sharp image of the wavelengths of interest in the +1-st and –1-st diffraction orders. The spectral lenses are convenient to use for obtaining remotely sensed vegetation index images instead of full-fledged hyperspectral images. We discuss the design and fabrication of spectral diffractive lenses for measuring vegetation indices, which include a Modified Red Edge Simple Ratio Index and a Water Band Index. We report synthesizing diffractive lenses with a microrelief thickness of 4 µm using the direct laser writing in a photoresist. The use of the fabricated spectral lenses in a prototype scheme of an imaging sensor for index measurements is discussed. Distributions of the aforesaid spectral indices are obtained by the linear scanning of vegetation specimens. Using a linear scanning of vegetation samples, distributions of the above-said water band index were experimentally measured.

Designing Freeform Micro Lens Array With Prescribed Luminous Intensity for LCD Backlight Units

Abstract: The precise luminous intensity control for liquid crystal display (LCD) backlight units is an important issue that has not been well addressed in current research. A proper luminous intensity distribution can significantly enhance the viewing experience. In this paper, we propose a method for designing a freeform micro lens array that is capable of producing a prescribed luminous intensity distribution for direct-lit LED backlight module. As the luminous intensity distribution is usually need to be constrained within a quadrilateral pyramid region, a special coordinate system is developed by scanning two semicircles containing light rays along the X axis and Y axis to provide a flexible model for luminous intensity tailoring. Further, we convert the luminous intensity design problem to a specific illuminance problem by using a lossless energy conversion strategy. Then, an integrable ray mapping between the source domain and the target domain is established to implement the freeform optics design to regulate the converted illuminance distribution. The effectiveness of the proposed method is verified via various design examples including on-axis configuration and axis-off configuration, the influence of the LED size on the optical performance is also analyzed.