This PDF file contains the front matter associated with SPIE Proceedings Volume 11483, including the Title Page, Copyright information, and Table of Contents.

A handheld, eye safe, EOIR, synthetic aperture, beyond-diffraction-limited, 3D imaging, prototype system has been demonstrated. The prototype uses a series of snapshot, simultaneous, multichannel, holographic images to derive all the necessary information to form synthetic aperture imagery. Each multi-channel, holographic image contains all the information necessary to form a snapshot, high-dynamic-range-depth 3-D image. The snapshot, 3-D imaging capability enables the prototype to be used as a handheld nondestructive evaluation tool for the inspection of visual surface defects on aircraft and other vehicles. The prototype’s snapshot, high-dynamic-range-depth specifications are approximately: 100mm³ 3-D field of view, 1mm3 voxel, with 0.1mm depth accuracy. These specifications are for given range to target of approximately 500mm and scale linearly with distance. The prototype operates at a continuum of ranges from about 100 to 1,000mm. The prototype’s synthetic aperture ability enables an increase in resolution and has been demonstrated to deliver an approximate 6x resolution increase as a result of random handheld motion and a 10x increase due to prescribed motion. All elements of the prototype are scalable, e.g., resolution, range to target, and dynamic range. The wavelength band is selectable to accommodate requirements such as eye safety or target material properties. The prototype represents a baseline capability for either handheld, snapshot, 3-D imaging, or under certain conditions, handheld, synthetic aperture, EOIR, beyond diffraction limited, 3-D imaging.

In this study, we describe a simple method to produce signals which can reveal the cross-sectional information of samples in an optical coherence tomography (OCT) system. Instead of using the spectrometer and the Fourier transformation calculation in the conventional spectrum domain (SD) OCT system, we use a Mach-Zehnder interferometer structure of the spatial heterodyne spectrometer. In a spatial heterodyne spectrometer, because each position on the photodetector array could be mapped to a specific optical path difference, the spectral density distribution could be retrieved with Fourier transformation. And in an SD-OCT system, cross-section signals are obtained by conducting Fourier transformation to the spectrum signals. Therefore, in our OCT system, the spatial signals captured by the photodetector array is related to the cross-sectional signals obtained in an SD-OCT system. The theoretical study and the numerical simulation demonstrate that by applying our method in an OCT system, the heterodyne spectrometer structure could generate a symmetrical pattern composed of fringes with high spatial frequency. Then the photodetector array captures the pattern to generate a spatial signal. The spatial ordinate of this signal is linearly related to the optical depth in sample, while the amplitude of the signal intensity variation is linearly related to the intensity of coherent backscattered light in the sample. The imaging depth is theoretically unlimited. Also, because of the high spatial frequency of the signal, we further adjust the inclination angle in the heterodyne spectrometer structure to visualize the signal.

Spectral analysis is an important method for noninvasive blood glucose measurement. Presently, Fourier-transform spectroscopy is a well-established technique that provides highly resolved spectral measurements in the infrared, visible and ultraviolet ranges. In this study, we proposed a novel method for obtaining linear spectra based on regular Spatial Heterodyne Spectrometers. In particular, we wanted to use a fluorescent dye-coated screen and a Fourier lens to directly obtain uniform K-space spectra. In the system, the up-conversion luminescent material on the screen is hoped to absorb coherent incident light and emit light of a specific wavelength that maintains the coherence. According to our calculation, the photodetector array receives the Fourier image pattern on the screen and can directly obtain the spectrum of the measured substance, therefore the scientists can directly observe the spectrum of the test sample. Furthermore, we replace the fluorescent dye-coated screen by an infrared laser detector card, which is commonly used in laboratories, to primary verify the feasibility of the method. Up-conversion luminescent materials that are widely used in the fields of analytical chemistry, biomedicine, and life sciences, have very good application prospects in biological imaging, photodynamic therapy, solar cells, flexible fluorescent films and sensing.

Artificial color treatment techniques have been applied to pearls of less appealing colors to improve their appearances and to increase their commercial values. In addition, separation of various types of pearls could be challenging due to similar characteristics among several closely related mollusk species. Currently gemological laboratories use various spectroscopic and imaging techniques in tandem, including x-ray imaging, microscopic observation, ultra-violet to visible reflectance spectroscopy, and Raman spectroscopy for various identification purposes. Due to the complexity of the protocol, there is a strong demand for a fast and simple identification method designed for gemological laboratories or users without advanced equipment or expertise, such as pearl dealers and jewelry manufacturers. We demonstrate a fluorescence detection system for pearl’s color treatment identification and species classification. A photoluminescence excitation spectroscopy was used to select the proper excitation wavelengths. Multiple light emitting diodes were selected as the sources; and spectrometers were used to monitor ultra-violet to visible fluorescence. The system can noninvasively analyze both loose pearls and mounted pearl jewelries under normal office lighting condition. Spectral analysis protocols were used to localize the trace of treatments and classify fluorescence features between different pearl types. The primary purpose of this device is to detect commonly used color treatments. Additionally, it may also classify pearls between the most common types in seconds, as suggested by preliminary study.

MOEMS-based instruments could be the next stepping stone for ground-based and space telescopes, allowing for multi-object spectroscopy in a 2D field of view. These programmable slit masks will optimize the SNR and generate compact and efficient spectro-imagers for Universe and Earth observation. BATMAN, a MOEMS-based spectro-imager for Universe observation to be installed at the TNG at the Canaria Islands, uses a Digital-Micromirror-Device to split the light between its imaging and spectrograph arms. ROBIN, the BATMAN demonstrator, confirmed its feasibility and image quality over the FOV. A new design for a DMD-based high-resolution spectro-imager for Universe observation is presented: a solution using only one detector for all the wavelength range is obtained. We are dividing the 370 – 950 nm wavelength range into four channels and a spectral resolution of 15 000 is achieved for every one of them, all within an image quality below two detector pixels. Moreover, the 3-mirror design of the instrument implies a high throughput in comparison to catadioptric systems which are more commonly used for this science case. A new MOEMS-based spectro-imager for Earth observation has been designed, with constraints of wide 2D field of view (3°×1°), image quality (< 2 pixels = 11 μm) and compacity. The instrument is panchromatic with a medium spectral resolution between 1000 and 2000, fitting in a 40 cm × 50 cm × 90 cm box. A 3-mirror solution for both imaging and spectrograph arms has been designed, using only aspheric surfaces thus allowing for easier alignment and tolerancing.

Skin chromophore maps can be used for assessment of various skin malformations and early cancer diagnostics. Commercially available devices are bulky and expensive. We present two portable proof-of-concept device prototypes for multi-spectral laser line imaging with three (448 nm, 532 nm and 659 nm) and four (450 nm, 523 nm, 638 nm and 850 nm) wavelength laser illumination. Laser modules and special optics that ensure uniform light distribution over the region of interest have been exploited. Skin chromophore maps were calculated using Beer-Lambert law, considering light scattering properties in the skin and including photon path length evaluated from the directly measured photon-time-of-flight signals. Chromophore concentrations in the lesion are compared to the surrounding healthy skin. In vivo measurement results were compared with the results obtained from agar-based multi-layered skin phantoms which mimic vascular and pigmented skin lesions.

The practice of photometric laboratory requires to receive uniform fields of illumination of different screens, apertures and sensitive areas of photo detectors in a wide spectral range of the optical spectrum (from ultraviolet to far infrared). At the same time, the level of illumination, as a rule, needs to vary within several orders of magnitude. The uniformity requirements associated with minimizing the error of photometric measurements can be quite high. While using such radiation source as “black-body” we can provide uniformity of illumination field at the rather long distances but at the same time we will not receive the required value of illumination. That could be improved by placing the right-angled four mirrored channel between the source and the photo detector. The optical radiation after numerous reflections from the mirrors reaches the surface raising the illumination level and the experiment shows the illumination uniformity of the mentioned surface is improving.

Global optimization of imaging lenses, non-sequential ray tracing for illumination (or stray light) analyses, FDTD modeling of 3D photonic devices, optical field calculations by the Gaussian beamlet method, and image simulations using very large 2D FFTs can be some of the most computer intensive tasks in optical engineering. An example of the first on reasonably–priced Intel/Microsoft platforms is used to test whether relevant single-core computational speeds have kept up with predictions, from the early 1990’s 32-bit 486s running extended DOS to today’s 64-bit CPUs running Windows 10. It is found that before around 2005, performance doubled every 18 months (equivalent to 100 times every decade) as predicted by House’s variant of Moore’s 1975 law. At that time thermal issues lead to a more efficient microarchitecture and a relative stagnation of CPU frequencies so progress slowed significantly, but could be mostly reclaimed by the effective utilization of a large number of computational cores. Therefore, previously published results comparing multi-core performance on the other tasks will be updated using nearly a decade newer CPUs and GPUs. Even though they have much higher clock rates and core counts than the old hardware, their relative performances fall short (and sometimes far short) of expectations.

Extended Depth of Focus (EDOF) systems have a broad set of applications in optics including enhancement of microscopy images and the treatment of presbyopia in the aging eye. The goal of EDOF systems is to axially elongate the region of focus for the optical system while simultaneously keeping the transverse dimension of the focus small to ensure resolution. The pinhole effect of reducing the size of the aperture is a well-known means of extending the depth of focus. The pinhole effect however has the drawback of reducing the light entering the system and reducing the resolution of the image. Alternatively, phase masks can be placed in the pupil to enhance depth of focus, maintain light levels and improve resolution relative to the pinhole system. Here, a technique for decomposing these phase masks into a set of quadratic phase factors is explored. Each term in the set acts like a lens and the foci of these lenses add coherently to give the overall focus profile of the system. This technique can give insight into existing EDOF techniques and be used to create novel EDOF phase masks.

The field of teleophthalmology has been expanding in recent years due to the development and advancement of mobile fundus cameras. Many of these devices involve taking a video of the retina using a smartphone coupled with an attachable lens system. Despite recent advances, the videos that are obtained with these devices can sometimes be difficult to use for clinical purposes. This is because the videos often have a small field of view and can include blurry frames and blinks. In order to improve the ease at which these videos can be obtained and interpreted, a stabilization system and Android application for processing these videos was created. This Android application is intended to exclude unusable video frames, and stitch together the remaining frames into a single image. The effectiveness of this application is tested using videos obtained with the D-EYE device. These images are then compared to clinical images, and images obtained from the DEYE without the image stitching application. In this study, the image quality of the stitched images was found to be worse than that obtained from a clinical device.

Increasing depth of field in imaging systems can be beneficial, particularly for systems with high numerical apertures and short depth of field, such as microscopy. Extending depth of field has been previously demonstrated, for example, using non-rotationally symmetric (freeform) components such as cubic and logarithmic phase plates. Such fixed phase plates are generally designed for a specific optical system, so a different phase plate is required for each system. Methods that enable variable extended depth of field for multiple optical systems could provide benefits by reducing the number of required components and costs. In this paper, we explore the design of a single pair of transmissive freeform surfaces to enable extended depth of field for multiple lenses with different numerical apertures through relative translation of the freeform components. This work builds on the concept of an Alvarez lens, in which one pair of transmissive XY-polynomial freeform surfaces generates variable optical power through lateral relative shifts between the surfaces. The presented approach is based on the design of multiple fixed phase plates to optimize the through-focus Modulation Transfer Function (MTF) for imaging lenses of given numerical apertures. The freeform surface equation for the desired variable phase plate pair is then derived and the relative shift amounts between the freeform surfaces are calculated to enable extended depth of field for multiple imaging lenses with different numerical aperture values. Design approaches and simulation results will be discussed.

Optical microstructures are of very high interest for delivering and or guiding optical radiation. Beyond the replacement of conventional hypodermic syringes, the use of microneedles opened the route towards portable lab on chip devices where the same microneedle could be used for drug delivery and photodynamic therapy, focusing the light thorough the needle tips. Here we propose for the first time an innovative approach for the fabrication of polymeric conical structures and the optical characterization of the light guided through a pyro-electrodrawn micro needle. A point-like thermal stimulation of a ferroelectric crystal enabled the electro-drawing of single or parallelized needles. The results reported show the possibility of tuning the geometry and the dimension of the structures produced and their use for controlling and guiding external light. The structures have been realized using a biocompatible and biodegradable polymer thus such conical structures in principle could be implantable. The conical structures have been characterized in terms of geometry, shape and emitted light profile. We report experimental results and discuss results and perspectives for exploiting them.

Dielectric nanophotonics became a hot topic during the last decade. Particularly, a lot of relevant studies were devoted to metasurfaces and their optical properties. Here we propose and numerically study the quadrumerbased silicon metasurface supporting magnetic octupole response. Specific meta-atoms allow to excite magnetic octupole moment in optical range without going beyond the diffraction limit. Comparing to a metasurface based on solid blocks of similar size, the quadrumer-based metasurface feature significant absorption enchantment and strong change of a reflection spectrum. Obtained results can be exploited in development of novel sensors, optical elements and energy harvesting devices.

To suppress the Fresnel reflection loss and enhance light transmission, subwavelength structured surfaces are used as antireflector. In this work, rigorous coupled wave (RCWA) analysis-based design approach has been adopted to simulate nano-sized moth-eye like structures on silicon substrate for wide-angle, short-wave infrared (SWIR) antireflector. Large reflection loss due to high refractive index of silicon is detrimental to optical performance. The proposed surface relief moth-eye structures introduce gradient refractive index to the surface depending on substrate materials, structure geometry, height, periods. Optimum selection of these parameters during design and fabrication are essential steps for the effective quelling of undesirable reflection from air-surface boundary and enhance transmission. Due to subwavelength nature, maintaining accuracy of all design parameters during fabrication on silicon is challenging. Careful tradeoff is required to fix tolerance of each parameter depending on priority to overall performance. In this work, with help of Taguchi optimization techniques, optimum combination of the structure height, periods, and top surface area of moth-eye structure are selected for antireflector. Analysis of variance (ANOVA) approach has been opted to identify the contribution of individual design parameters to performance. This performance model based on RCWA design, Taguchi optimization techniques and ANOVA analysis acts as a tool to predict the performance trend and fix tolerance of design parameters. For wavelength range (700nm -3000nm), with optimized height 600 nm, period 200 nm, and flat top diameter 70 nm of tapered moth-eye structures, the obtained reflectance is less than 1 % for the incidence angle up-to 45°.

In this work, the optical absorption analysis of the Vertical Photodetector for Optical Interconnect is done. For efficient detection of the signal at the receiver, a photodetector is required for designing of efficient optical interconnects. The light transmitted from the optical source is coupled into the waveguide and received by the detector. Vertical photodetector can be designed using Si and Ge but due to large bandgap, Si can’t detect the optical signal efficiently at wavelengths used for optical communication (1.3 to 1.55 μm). This can be done by using smaller band gap material (Ge) to design a photo- detector. Ge photo- detector offer high performance optical interface solutions. The Optical absorption property of photodetector is analyzed using Lumerical FDTD. It is observed that the absorption rate of vertical Ge-Si photodetector vary in different plane and provides high responsivity at 1.55 μm because the region of absorption can be made longer to enable full absorption. We investigate the absorption rate of the designed vertical photodetector because the responsivity of the photodetector depends on the absorption rate. The designed structure can be used in on-chip optical interconnect with high absorption rate and low cost.

The limitation of conventional electronics is reduced by optical integrated circuits because of its high speed information and processing. Reversible logic gates are favorable in the processing of optical signals in optical domain. In all reversible gates inputs and outputs are correlated that is advantageous to collect the information from inputs and outputs. Reversible gates are useful in high speed data transmission with low power dissipation. Reversible gates are also used in quantum computing with low loss of information. In the current work, Reversible Feynman and Fredkin optical gates are designed using Mach Zehnder Modulator for high speed information processing. A Mach Zehnder Modulator has capability to switch the source light according biased electrical signal. The amount of biased electrical signal modulates the output. The reversible optical gates are used in optical switching, optical modulator and as protection switch. The proposed gates are explained with mathematical formulation and the truth table of the reversible gates is verified using Lumerical Interconnect tool.

Birefringent color filters serve a critical role in next generation display systems, including augmented-/virtual- /mixed-reality headsets, and many types of optical remote sensing. Most prior polarization interference filters (PIFs) employ many individually aligned plates that enable only relatively thick color filters (≥ 100s of μm), are usually limited to small clear apertures (few cm), and offer poor off-axis performance. Here, we report on a family of monolithic, thin-film, birefringent PIFs formed using liquid crystal polymer (LCP) network materials, also known as reactive mesogens. These multi-twist retarders (MTRs) are only a few µm thick and have a single alignment surface. They offer high color saturation with a notch-type pass/stopband, analogous to Solc filters, and improved off-axis performance and large-area scalability. Here, we apply simplifying assumptions inspired by Solc-type PIFs, and develop a design method resulting in MTRs with an alternating achiral/chiral architecture. We design three representative color filters (blue-yellow, green-magenta, and cyan-red), and fabricate them. The resulting experimental films manifest strong color filtering behavior, with high saturation and uniformity. We study the color differences for oblique incidence, showing modest change within AOI ≤ 20°.

The broadening of the P9P9 absorption line of oxygen molecules entrapped in the pores of nanoporous alumina is studied using Gas in Scattering Media Absorption Spectroscopy (GASMAS). A narrow band tunable vertical-cavity surface-emitting laser (VCSEL), with emission peaking around 763 nm, is used to scan over the absorption line of the oxygen A-band. The oxygen line broadening in alpha alumina discs of pore sizes 150 nm, 80 nm and 50 nm, are measured to be 3.8 GHz, 4.2 GHz, and 4.8 GHz, respectively, and compared with the measured open-air oxygen line broadening of 3.3 GHz. The oxygen line broadenings are correlated with studied samples pore sizes and are found to agree well with the line broadenings evaluated using a model based on collisions of confined oxygen molecules with the bulk sample pore walls.

Experimentally compared for the first time is the sensitivity of two magnetometer types implemented on a common base of rubidium atomic clock with coherent population trapping (CPT). The first magnetometer used a magneto-sensitive optically excited CPT resonance, the other measured field strength through the electron paramagnetic resonance (EPR) excited with alternating magnetic field. We show advantages and limitations of these promising quantum sensing technologies. Sensitivity of both types was measured under resonance excitation on the D1 line of ⁸⁷Rb. We demonstrate that the СРТ magnetometer sensitivity may exceed that of the EPR device by two orders of magnitude.

Chip-based optical nanoscopy, relying on single molecule localization microscopy has recently been demonstrated to reach 70 nm lateral resolution over wide fields of view (500 µm x 500 µm). To make this technique more sustainable for live-cell imaging we embedded a photonic chip into a microfluidic support that is able to perfuse and thermalize the samples. In this way specimens are maintained under physiological conditions during the imaging which can be a timeconsuming process. The system consists of a multilayer chip with the size of a glass coverslip (60 mm × 24 mm). The sample is illuminated using waveguides that are fabricated from high refractive index material. The waveguide hosts a chamber (17.3 μl) where cells are seeded and perfused with medium. A thin layer (188 µm) of cyclic olefin polymer (COP) seals the chamber and allows optical image acquisition. A thermalizing solution is perfused from the bottom to accurately warm up/cool down the waveguide in a range of 5°C - 45°C. Thus, samples are kept at the proper temperature. As proof of concept and verification of super-resolution imaging, we imaged fluorescent beads perfused across the coated surface (fibronectin 0.2 mg/ml) of the chip, which is needed to guarantee proper cell-to-substrate adhesion.

In this paper are presented: structural-logical diagram and design of a phasemetric study of microscopic images of blood films of laboratory rats; model analysis of the polycrystalline structure of blood films of laboratory rats; structurally logical diagram and characteristics of the optical arrangement of the system of phasemetric mapping of microscopic images of blood films of laboratory rats; algorithms for statistical processing of experimental data of a system for phasemetric mapping of microscopic images of blood films of laboratory rats; information analysis algorithms to determine the strength of the diagnostic method of phasemetric mapping of microscopic images of blood films of laboratory rats by establishing a set of operational characteristics - sensitivity, specificity and accuracy.

This study describes a sensitivity analysis of absorption-spectrum transferability with respect to substrates for optimizing NIR-SWIR reflectance of dyed materials with respect to specified target spectra. Inverse modeling is applied to reflectance spectra of prototypical IR absorbing dyes, which have been deposited upon different substrates, with different deposit-layer thicknesses. IR absorption features of any given IR absorbing dye will be a function of deposit-layer microstructure and dielectric response of substrate material. This study examines the feasibility of parametrically modeling absorption-spectrum dependence on dye-deposit microstructure and dye-deposit-substrate interaction, which will depend on the sensitivity of absorption-spectrum transferability with respect to different types substrates.

Cryodestruction is one of the promising medical techniques, which has a lot of advantages. Unfortunately, the monitoring of the ice-ball formation in biological tissue during their freezing is a severe problem. In order to solve it, we suggest applying diffuse reflectance spectroscopy and terahertz spectroscopy for monitoring and implement it by means of a special cryoapplicator, based on sapphire shaped crystals. Sapphire features high transparency in a wide spectral range, chemical resistance, and high thermal conductivity at the cryogenic temperatures, therefore, it is an appropriate material for cryotherapies. Moreover, the technique of growing shaped sapphire enables fabrication of applicators of complex shapes and cross-sections. We demonstrate an example of such applicator of an immersion type with several channels for optical fibers, experimental set-up for study its abilities and experimental results of approbation of such applicator.

In this paper, we report an investigation on Polarization Beam Combining (PBC) of two laser beams through simulation and experimental studies. The polarization beam combining of two 100 W fiber laser beams with overall efficiency 98% has been demonstrated. We have compared the output beam stability and efficiency in both coherent and incoherent cases for different power levels. Simulations shows that the combined beam intensity and its stability are not degraded significantly due to phase correlation between beams, which is validated through our experimental results.

Gradient Index (GRIN) Optics is a challenging frontier of lens design. We have developed a free, online toolbox for generating gradient optics dynamic linked library (GODLL) files representing an arbitrary, user-defined gradient index profile for use with Zemax OpticStudio. In order to show the accuracy, user-experience and the procedure for usage of GODLL, we have demonstrated the performance of our toolbox using several popular or extreme examples consisting of Maxwells Fisheye Lens, Luneberg Lens, and a typical SELFOC lens.

This study was designed to ceramic brackets debonding through conventional remove and two lasers (980 nm diode laser and 1064 nm Nd:YAG laser) irradiation on the interface between the teeth and the bracket. After bracket removal, the enamel surfaces were examined using a digital microscope and the corresponding adhesive remnant index (ARI) score was assessed using 20x magnification. Experiments were conducted and comparisons made between the mechanical remove and laser methods, and results are presented that show lasers were good for clinical to effectively debonding ceramic brackets instead of conventional method. The laser assisted debonding of ceramic brackets is capable of lower the risk of enamel damage. Two lasers used in the experiment, the Nd:YAG laser with line beam scanning method was applied to the bracket removal compared to the diode laser. The suggested technique is expected to be useful in the field of orthodontics.