Papers by Keyword: Optical Sensing

Abstract: Optical self-sensing employs the reinforcing fibres as self-sensing elements thus eliminating the need for additional sensing elements in smart materials. At present optical self-sensing systems employ expensive optical adhesives to lower the refractive index of the matrix as the refractive index of the cladding material must be lower than the light-guiding glass fibres. In this study the refractive index of an aerospace certified, commercial laminating resin (Araldite LY5052/Aradur HY5052) was reduced with propylene carbonate, (a commercial reactive diluent). This modified resin with lower refractive index facilitated light transmission through impregnated E-glass reinforcing fibres used as optical self-sensing elements in composites. The effects of propylene carbonate addition on the mechanical properties of the epoxy were also analysed and presented here.

Abstract: In this paper, we present some distinguished methods of the digital thermograms software treatment which allows the visualization of hidden defects in glass fabric laminates, which are not usually visible in standard raw thermograms. The results of the software treatment are tested on artificial defects in glass laminate plates.

Abstract: Because of their size and versatile chemistry, nanomaterials represent today powerful tools for (bio) sensing applications. Various types of nanomaterials have proven to be practical, not only for the determination of clinically relevant parameters, but also for diagnostics, drug delivery and treatment of diseases (e.g. cancer). In this short review, types of nanomaterials used in medical applications are briefly described along with some of their applications where the nanomaterials optical properties can be exploited. The question of the toxicity of nanomaterials and the issue of future trends are also raised.

Abstract: In recent years, with the development of optical communication by leaps and bounds, promote the Micro-opto-electro-mechanical system (MOEMS) development. As a new technology, the MOEMS have been widely used in optical communication, optical switching, data storage, optical sensing and etc.. Compared with the traditional pressure sensors, the optical pressure sensor based on MOEMS has some unique advantages. In this paper, the structures, operation principles and fabrication processes of various MOEMS pressure sensors are described mainly. Finally, the structure and Key technology of a MOEMS pressure sensor array is presented in brief.

Abstract: In recent years optical disks have been very popular and in manufacturing process error detection in optical disks becomes very important, especially for the defects whose size of a few millimeters in length and several hundred nanometers in depth. The authors have developed a new system to measure the defects of disk substrates using a Mach-Zehnder interferometer with a phase shifting method. But it was found that optical disks had undulation of the optical thickness and it disturbed the detection of defects. To solve the problem moving-average method was developed and introduced in data processing to distinguish the defect from the undulation, and with modified unwrapping program the defect was visualized by binary image processing.

Abstract: Sensing marine plankton plays a key role in biological oceanography system. Lots of sensing marine plankton systems using different methods are developed so far with different functionality. In this paper, a systematic analysis of most methods used is summarized for direct sampling measurement, electron counting measurement, acoustic detection measurement and optical observation measurement. Technical and functional properties of developed devices are systematically analyzed and problems are also given. Finally, future needs and possible research directions are provided.

Abstract: A wavelength-tunable laser is a powerful tool as light source for sensing and its research and development has been studied so far. In order to obtain a new tunable laser the authors have developed a tunable Er³⁺-doped fiber laser in Littman/Metcalf configuration, and incorporating a Galvano mirror, scanning of the lasing wavelength is demonstrated. For the emission range that a semiconductor-based light source hardly covers, a tunable Tm³⁺-Ho³⁺ fluoride fiber laser is also demonstrated.

Abstract: An optical ammonia probe was fabricated based on Microstructured Polymer Optical Fiber (MPOFs) modified by eosin doped silica gel films.The structure of this probe was based on microstructured polymer optical fibers with microholes and these microholes could be used as the substrate of sensing materials and minor reaction pools. The sensing properties of the optical fiber sensor to gaseous ammonia were investigated at room temperature. The sensing probe showed different fluorescence intensity at 576 nm to different concentrations of trace ammonia in carrier gas of nitrogen. The response range was 20-350 ppm, with short response time within 600 ms.

Abstract: A glass substrate was sputter-etched by R. F. magnetron sputtering at the powers of 100 or 200 W for 60 min in Ar gas. Pd thin film as a sensing agent of hydrogen (H2) was deposited on the glass substrate. The durability of the sensor was evaluated during hydrogen absorption-desorption cycles. The Pd thin film on the glass substrate without sputter etching peeled off after dozens of the cycles. However, the Pd thin film on sputter-etched glass substrate didn’t peel off. The contact angle of water on the glass substrate with sputter etching was smaller than that without sputter etching, suggesting that the surface energy of the substrate was increased by employing the sputter etching process. The improvement of durability for the optical hydrogen sensor using sputter etched substrate was related to the increase of surface energy induced by the sputter etching.

Abstract: For flexible 3D positioning of a complex 3D mechanism, it is needed to measure 3D displacement of the end-effecter of the mechanism in high precision and by non-contact method. It was common to use plural sensors or scales together to measure the 3D displacement. However, it is difficult to calibrate the sensitivities of the plural sensors or scales. A novel 3D displacement measurement is proposed using an optical system in which lens focuses are collected at the center of the sphere, which has been used for the radius measurement of the sphere. Instead of facing in the XY direction that has high sensitivity, new ideas are necessary for the measurement in the Z direction of the optics where focuses are collected at the center of the sphere. The displacement in the XY direction and the one in the Z direction can be measured at the same time by using a ring-shaped laser beam instead of a simple ray.