Assessing microlens quality based on 3D irradiance measurement at the focal spot area

During the fabrication process of microlenses, characterization is essential for two purposes: evaluate the optical quality of the element and provide surface information feedback for process optimization. However, no technique can fulfill these two objectives at the same time. Interferometry is used for quality evaluation and optical profilometry for process optimization. In order to address this problem, we propose to use a high resolution interference microscope to characterize microlenses. The focusing capacity can be directly measured by recording the field near the focal spot at different wavelengths. Information about the microlens surface can also be retrieved. All this is illustrated for the front focus of a fused-silica microlens

Inspection and profiling of moving objects using a TDI camera

Proceedings of SPIE - The International Society for Optical Engineering2921563-570PSIS

Defect measurement using structured light system

Proceedings of SPIE - The International Society for Optical Engineering2921529-534PSIS

Signature Optical Cues: Emerging Technologies for Monitoring Plant Health

Optical technologies can be developed as practical tools for monitoring plant health by providing unique spectral signatures that can be related to specific plant stresses. Signatures from thermal and fluorescence imaging have been used successfully to track pathogen invasion before visual symptoms are observed. Another approach for noninvasive plant health monitoring involves elucidating the manner with which light interacts with the plant leaf and being able to identify changes in spectral characteristics in response to specific stresses. To achieve this, an important step is to understand the biochemical and anatomical features governing leaf reflectance, transmission and absorption. Many studies have opened up possibilities that subtle changes in leaf reflectance spectra can be analyzed in a plethora of ways for discriminating nutrient and water stress, but with limited success. There has also been interest in developing transgenic phytosensors to elucidate plant status in relation to environmental conditions. This approach involves unambiguous signal creation whereby genetic modification to generate reporter plants has resulted in distinct optical signals emitted in response to specific stressors. Most of these studies are limited to laboratory or controlled greenhouse environments at leaf level. The practical translation of spectral cues for application under field conditions at canopy and regional levels by remote aerial sensing remains a challenge. The movement towards technology development is well exemplified by the Controlled Ecological Life Support System under development by NASA which brings together technologies for monitoring plant status concomitantly with instrumentation for environmental monitoring and feedback control

Microparticle characterization using digital holography

Digital holography is an effective 3D imaging technique, with the potential to be used for particle size measurements. A digital hologram can provide reconstructions of volume samples focused at different depths, overcoming the focusing problems encountered by other imaging based techniques. Several particle analysis methods discussed in the literature consider spherical particles only. With the object sphericity assumption in place, analysis of the holographic data can be significantly simplified. However, there are applications, such as particle analysis and crystallization monitoring, where non-spherical particles are often encountered. This paper discusses the processing of digital holograms for particle size and shape measurement for both spherical and arbitrarily shaped particles. An automated algorithm for identification of particles from recorded hologram and subsequent size and shape measurement is described. Experimental results using holograms of spherical and non-spherical particles demonstrate the performance of the proposed measuring algorithm

Visualization 1: Full-color holographic display with increased-viewing-angle

Increased viewing-angle full-color image. Originally published in Applied Optics on 01 May 2017 (ao-56-13-F112

Localization of Microfibers within Volumes Using Digital Holographic Video

Carbon fibers are studied using digital holographic sequences. Fibers have distinct orientation in space. An algorithm to identify the orientation and the size of suspended fibers from the digitally recorded holographic sequences is presented

Localization of Microfibers within Volumes Using Digital Holographic Video

Carbon fibers are studied using digital holographic sequences. Fibers have distinct orientation in space. An algorithm to identify the orientation and the size of suspended fibers from the digitally recorded holographic sequences is presented