Search

White blood cell (WBC) and neutrophil counts are important laboratory tests used by clinicians to assess a variety of conditions. However, current methods to measure WBC and neutrophil counts are difficult to perform at the point of care, being either cost or labor prohibitive. To meet this need, we developed the LeukoScope: a portable, imaging-based system to measure WBC and neutrophil counts from a drop of blood. Here, we present the performance of the LeukoScope in 136 pediatric and 164 neonatal subjects at a central hospital in Malawi. For pediatric patients, 95.4, 66.7, and 80.0% of samples with normal, low, and high WBC counts, respectively, were correctly identified, and 88.6, 100.0, and 89.3% of samples with normal, low, and high neutrophil counts, respectively, were correctly identified. Accuracy was lower overall for neonatal samples; 92.1, 64.3, and 26.7% of samples with normal, low, and high WBC counts, respectively, were correctly identified, and 73.2 and 78.6% of samples with normal and high neutrophil counts, respectively, were correctly identified. Results of this study show that the LeukoScope can help meet need for point-of-care measurement of WBC counts in pediatric patients and highlight the challenges of point-of-care assessment of WBC counts in neonatal patients.

Calcium fluoride and zinc sulfide crystals exhibit broad multispectral transparency and are used for a multitude of optical applications. However, they both belong to a soft brittle crystal category and are mechanically challenging to process. Thus, a fabrication protocol using a single-point diamond turning method was developed, which can yield surfaces with optical quality for these materials. By using a diamond turning tool with low waviness (≤100-nm waviness) and by using feed rates of 1 and 0.2 μm / rev, CaF2 and ZnS surfaces with surface roughness of 6 and 5 nm were manufactured, respectively. Design and fabrication of a miniature objective with 0.5 NA are also presented, which was developed for the ultrafast laser microsurgery application. The objective consists of CaF2 and ZnS lenses to withstand the high power from ultra-short laser pulses and to provide a tightly focused beam with 1.23 μm 1 / e2 spot radius for laser ablation. Based on the spot size measurement of the objective, its performance was considered to be near diffraction limited.

A white blood cell (WBC) count with partial differential is an important clinical laboratory test. However, current methods to perform a WBC count and differential are difficult to use at the point of care or too expensive for use in low-resource settings. To meet this need, we developed the LeukoScope: a low-cost system to measure a WBC and neutrophil count from a single drop of blood at the point of care. The LeukoScope is battery powered and has a sample-to-answer time of

White blood cell (WBC) and neutrophil counts are important laboratory tests used by clinicians to assess a variety of conditions. However, current methods to measure WBC and neutrophil counts are difficult to perform at the point of care, being either cost or labor prohibitive. To meet this need, we developed the LeukoScope: a portable, imaging-based system to measure WBC and neutrophil counts from a drop of blood. Here, we present the performance of the LeukoScope in 136 pediatric and 164 neonatal subjects at a central hospital in Malawi. For pediatric patients, 95.4, 66.7, and 80.0% of samples with normal, low, and high WBC counts, respectively, were correctly identified, and 88.6, 100.0, and 89.3% of samples with normal, low, and high neutrophil counts, respectively, were correctly identified. Accuracy was lower overall for neonatal samples; 92.1, 64.3, and 26.7% of samples with normal, low, and high WBC counts, respectively, were correctly identified, and 73.2 and 78.6% of samples with normal and high neutrophil counts, respectively, were correctly identified. Results of this study show that the LeukoScope can help meet need for point-of-care measurement of WBC counts in pediatric patients and highlight the challenges of point-of-care assessment of WBC counts in neonatal patients.

A frequency modulation technique is described to distinguish between particle signals and stray light in a prototype of a photolithographic mask inspection system. Strict cleanliness requirements apply to the reticles used in photolithography, and to guarantee correct alignment and pattern reproduction both sides of a reticle (pellicle on front side and reticle back side) need to be inspected for contamination. Reticles constitute difficult inspection targets for imaging systems, because their diffractive patterns can redirect light in arbitrary directions which may potentially result in false positive detections. In this paper we introduce a frequency encoded structural illumination system which enables automatic delineation between stray light and particle signal. In our approach, a sinusoidal pattern whose temporal frequency changes with spatial coordinates is used to obliquely illuminate the surface under test. Incoherent illumination is used, and thus the signal recorded by the imaging optics positioned normal to the inspected surface is a superposition of light scattered by particles and stray light redirected by the photolithographic pattern. Because the inspected surface and reticle pattern are from the perspective of an observation system axially separated, the frequency response of each individual detector point is z position dependent. Therefore, Fourier analysis can be used to analyze the frequency content of each pixel individually and by comparing measured with expected frequencies, one can distinguish between light scattered by particles and stray light. The frequency encoding technique can be used in both imaging and scatterometry based systems. Example experimental results are presented.

We present an ultrafast laser surgery probe for bone tissue microsurgery. A custom miniaturized CaF2 mitigated the strong multiphoton absorption observed in our previous ZnS-based design while providing tighter beam focusing over a larger ablation field-of-view. The objective produced a beam waist radius of 1.71 μm covering a 130×130 μm2 scan area, delivering fluences >8 J/cm2 at the tissue surface at 53% transmission efficiency. The entire opto-mechanical system, enclosed within a 14 mm diameter metal housing with a 2.6 mm probe tip, exhibited material removal rates >0.1 mm3/min in bovine cortical bone. We performed simulations when using a high-power fiber laser and found that material removal rates >40 mm3/min could be achieved through selection of optimal laser surgery parameters. The device can serve as a clinically viable solution for minimally invasive spinal surgery applications.

EUV and DUV reticles are inspected before exposure to guarantee the quality of the lithographic process. The pellicle and the reticle back side are typically inspected for the presence of contaminants which are several micrometers in diameter. While detection of macroscopic particles is fairly straightforward, delineation between particle and stray light due to diffractive properties of reticle pattern is challenging. We present a particle detection system based on structural illumination technology capable of automatic delineation between contaminants and stray light. During measurement a series of images is acquired by a macro-imaging optical detector (e.g. camera) positioned normal in reference to the investigated sample. The surface under test is illuminated at an oblique angle by an incoherent polychromatic projection system projecting a pattern whose temporal frequency changes across the inspected surface. The signal acquired by the detector is in general an incoherent sum of light scattered by particles with stray light returned by the diffractive pattern. Temporal samples of intensity data are analyzed pixel by pixel in the Fourier domain and the particles are differentiated from the stray light by comparing the Fourier spectra of the acquired signal with the frequency a particle should generate at an analyzed pixel based on the system geometry. Thus, unwanted stray light signal contributions are separated from particle signal by performing logical operations on the signal in the Fourier domain. Experimental results from a technology demonstrator are provided to illustrate performance.

We present a miniaturized ultrafast laser surgery probe with improved miniaturized optics to deliver higher peak powers and enable higher surgical speeds than previously possible. A custom-built miniaturized CaF2 objective showed no evidence of the strong multiphoton absorption observed in our previous ZnS-based probe, enabling higher laser power delivery to the tissue surface for ablation. A Kagome fiber delivered ultrashort pulses from a high repetition rate fiber laser to the objective, producing a focal beam radius of 1.96 μm and covering a 90×90 μm2 scan area. The probe delivered the maximum available fiber laser power, providing fluences >6 J/cm2 at the tissue surface at 53% transmission efficiency. We characterized the probe’s performance through a parametric ablation study on bovine cortical bone and defined optimal operating parameters for surgery using an experimental- and simulation-based approach. The entire opto-mechanical system, enclosed within a 5-mm diameter housing with a 2.6-mm diameter probe tip, achieved material removal rates >0.1 mm3/min, however removal rates were ultimately limited by the available laser power. Towards a next generation surgery probe, we simulated maximum material removal rates when using a higher power fiber laser and found that removal rates >2 mm3/min could be attained through appropriate selection of laser surgery parameters. With future development, the device presented here can serve as a precise surgical tool with clinically viable speeds for delicate applications such as spinal decompression surgeries.

High-resolution endomicroscopy techniques are limited in field-of-view by the fiber optic probe size. We present a prototype for screening cervical tissue across a 25 mm field-of-view using a high-resolution image guide and image-stitching algorithm.

An achromatization method optimized for dual-channel imaging is developed. Dichroic mirrors are employed to split and recombine narrowband signals, and separation between catoptric components is used to minimize the longitudinal chromatic shift. An achromatic system based on this principle could be built from singlet lenses, since refractive element properties such as dispersion and power are not utilized to optimize wavelength-dependent performance. To demonstrate the validity of the proposed solution, a prototype miniature fluorescence microscope optimized for two emission lines of acridine orange (525 and 650 nm) is built. To reduce the cost and accelerate assembly, the system is built from commercially available optical components. The optical train consisted of two plastic singlet lenses combined with a pair of dichroic mirrors. Optical performance of the prototype is evaluated by imaging a bar line target at both design wavelengths. To demonstrate the potential of the proposed design strategy, the achromatic system prototype is used to measure a two-part white blood cells differential count on a venous blood sample. Data from the prototype fluorescence microscope are compared against results from a commercially available blood analyzer, and the difference between both instruments is within 20%.

Fiber bundle endomicroscopy techniques have been used for numerous minimally invasive imaging applications. However, these techniques may provide limited spatial sampling due to the limited number of imaging cores inside the fiber bundle. Here, we present a custom-fabricated miniature objective that can be coupled to a fiber bundle and can overcome the fiber bundle’s sampling threshold by utilizing the spectral encoding concept. The objective has an NA of 0.3 and an outer diameter of 2.4 mm, and can yield a maximum spatial resolution of 2 μm. The objective has been validated against a USAF resolution target and ex vivo tissue samples, and as a result yielded images with higher resolution and more details after the spectral encoding concept was employed.

At the primary care setting, where there are often no or minimal laboratories, examinations often consist of self-testing and rapid diagnostics. Because of this, medical devices must be simple, robust, and easy to operate. To address these concerns, an alternate fluorescence microscope design uses ultraviolet (UV) excitation, since fluorescent dyes that are excitable in the visible region are also excitable by UV. This may allow for the removal of typical excitation, emission, and dichroic filters as optical components absorb UV wavelengths and UV is not detected by silicon based detectors. Additionally, UV has a very low penetration into samples, which may allow for controlling the depth of excitation, and thus the imaging volume. Based on these ideas, we developed a simple fluorescence microscope built completely from off-the-shelf components that uses UV to image fluorescently stained samples. The simple opto-mechanical design of the system may allow it to be more compact and easy to use, as well as decrease the overall cost of the diagnostic device. For biological validation, we imaged whole blood stained with acridine orange and performed a two-part white blood cell differential count.

Due to the growth of miniature unmanned aerial vehicles (UAVs) and small spacecraft (SmallSats) in recent years, there has been a push for the development of miniaturized spectral imagers to be incorporated with them. An efficient, compact hyperspectral imager integrated with these vehicles provides a cost-effective platform for environmental sensing applications that include the monitoring of agriculture, vegetation, geology, and pollutants. We present here the development and integration of a hyperspectral imaging system called the SNAP-IMS, originally used for biomedical detection, with an Octocopter UAV. The entire collected hyperspectral data cube is 350x400x55 (x,y,λ) spatial/spectral samples. The final system enclosure (288 mm x 150 mm x 160 mm) weighs 3.6 kg (7.9 lbs), offering minimal size and weight. The payload’s power consumption is marginal as there are no mechanical scanning components; the existing power requirements are dedicated exclusively to CCD frame acquisition. Experimental testing included several flights on board the Octocopter UAV, acquiring hyperspectral data cubes at 1/100 second. Snapshot mode and short integration times mitigate motion artifacts. The low size, weight, and power consumption can offer longer and higher flights at smaller drone sizes. These improvements augment the potential for additional instrument incorporation (i.e. LiDAR, Multi-spectral IR) in the future. Imaging results and system description are presented and discussed.

We present the development of an endoscopic ultrafast laser scalpel with improved miniaturized optics as a follow-up to our previous studies. We previously determined that the nonlinear susceptibility of ZnS crystal lenses at high pulse energies can limit the maximum energy reaching the tissue surface. Here, we improve the nonlinear properties of miniaturized optics using CaF2 in lieu of ZnS as a lens material to mitigate the problem of three-photon absorption at the high energies needed for rapid tissue ablation. We built and tested a miniaturized objective consisting of a CaF2 crystal lens pair to focus ultrashort laser pulses delivered through a large air core Kagome fiber to a 3.4 μm diffraction limited spot and scan the beam with a piezo-tube across a 100×100 μm^2 field of view (FOV). Negligible three-photon absorption and high transmission through the probe (>50%) allows for delivery of fluences >8.0 J/cm^2. The entire opto-mechanical system, enclosed within a 5-mm hypodermic tubing, can remove tissue at material removal rates (MRR) >0.5 mm^3/min in excised soft (porcine vocal folds) and hard (bovine rib bone) tissue samples. We found that MRRs could be increased by the optimized combination of piezo- and translation scanning parameters, providing clinically relevant tissue removal speeds. Further, we present the first ultrafast tissue ablation experiments in a live animal model (hamster cheek pouch) using a handheld surgical probe. Towards clinical acceptance, we designed an injection-molded enclosure to seal the 5-mm diameter opto-mechanical assembly and constituent wires into a sterilization-ready ergonomic handheld stylus tool.

Imaging techniques e.g. field slicing and mapping, fiber field arrays to rapidly acquire multi-dimensional data are discussed. They allow recording and display of spectral, polarization and in general 3D+ information in a snapshot mode.

We present the development of a 5 mm, piezo-actuated, ultrafast laser scalpel for microsurgery with a capability to deliver energies in excess of 1 μJ per pulse. Having previously established that the maximum energy deliverable was limited by cladding damage in photonic badgap fibers, we utilized a large, 35μm cored inhibited-coupling Kagome fiber that allowed the delivery of micro-Joule energy femtosecond pulses. To maintain diffraction limited performance over the entire scan range of the piezo-actuated fiber tip, special objective lenses were developed and manufactured out of a high-refractive index Zinc Sulfide (ZnS) crystal. The probe was packaged in hypodermic 304SS stainless steel with a form factor minimizing in-line configuration. The probe’s performance was tested via metal and tissue ablation studies, characterizing highspeed ablation parameters and uniformity of ablation over the scan area. Additionally, we studied the nonlinear performance of ZnS and Calcium Fluoride (CaF2) as materials for refractive optics and determined the maximum energy deliverable through our probe using these optical materials. The high energy delivery through the probe system should allow for fast and effective tissue ablation.

We designed an achromatic microscope using off-the-shelf singlets and dichroic mirrors. The system chromatic performance was optimized for emission wavelengths of acridine orange. Application includes differential white blood cell (WBC) imaging in point-of-care settings.

We developed a tunable miniature fluorescence microscope that takes advantage of chromatic aberrations to image samples with more than one fluorophore. We show that the system can image acridine orange stained whole blood samples.

A high frame rate Image Mapping Spectrometer was developed. At the maximum resolution, instrument can acquire data at the rate of 100fps. The presented spectrometer provides a data-cube of 210×279×54 samples, instrument spectral range:515-842 nm.

A prototype fiber-based imaging spectrometer was developed to provide snapshot hyperspectral imaging tuned for biomedical applications. The system is designed for imaging in the visible spectral range from 400 to 700 nm for compatibility with molecular imaging applications as well as satellite and remote sensing. An 81 × 96 pixel spatial sampling density is achieved by using a custom-made fiber-optic bundle. The design considerations and fabrication aspects of the fiber bundle and imaging spectrometer are described in detail. Through the custom fiber bundle, the image of a scene of interest is collected and divided into discrete spatial groups, with spaces generated in between groups for spectral dispersion. This reorganized image is scaled down by an image taper for compatibility with following optical elements, dispersed by a prism, and is finally acquired by a CCD camera. To obtain an (x, y, λ) datacube from the snapshot measurement, a spectral calibration algorithm is executed for reconstruction of the spatial-spectral signatures of the observed scene. System characterization of throughput, resolution, and crosstalk was performed. Preliminary results illustrating changes in oxygen-saturation in an occluded human finger are presented to demonstrate the system's capabilities.

Purpose Retinal angiography evaluates retinal and choroidal perfusion and vascular integrity and is used to manage many ophthalmic diseases, such as age-related macular degeneration. The most common method, fluorescein angiography (FA), is invasive and can lead to untoward effects. As an emerging replacement, noninvasive OCT angiography (OCTA) is used regularly as a dye-free substitute with superior resolution and additional depth-sectioning abilities; however, general trends in FA as signified by varying intensity in images are not always reproducible in the fine structural detail in an OCTA image stack because of the source of their respective signals, OCT speckle decorrelation versus fluorescein emission. Methods We present a noninvasive/dye-free analog to angiography imaging using retinal hyperspectral imaging with a nonscanning spectral imager, the image mapping spectrometer (IMS), to reproduce perfusion-related data based on the abundance of oxyhemoglobin (HbO2) in the retina. With a new unmixing procedure of the IMS-acquired spectral data cubes (350 × 350 × 43), we produced noninvasive HbO2 maps unmixed from reflectance spectra. Results Here, we present 15 HbO2 maps from seven healthy and eight diseased retinas and compare these maps with corresponding FA and OCTA results with a discussion of each technique. Conclusions Our maps showed visual agreement with hypo- and hyperfluorescence trends in venous phase FA images, suggesting that our method provides a new use for hyperspectral imaging as a noninvasive angiography-analog technique and as a complementary technique to OCTA. Translational Relevance The application of hyperspectral imaging and spectral analysis can potentially improve/broaden retinal disease screening and enable a noninvasive technique, which complements OCTA.

A fiber-based snapshot imaging spectrometer was developed with a maximum of 31853 (~188 x 170) spatial sampling and 61 spectral channels in the 450nm-750nm range. A compact, custom-fabricated fiber bundle was used to sample the object image at the input and create void spaces between rows at the output for dispersion. The bundle was built using multicore 6x6 fiber block ribbons. To avoid overlap between the cores in the direction of dispersion, we selected a subset of cores using two alternative approaches; a lenslet array and a photomask. To calibrate the >30000 spatial samples of the system, a rapid spatial calibration method was developed based on phase-shifting interferometry (PSI). System crosstalk and spectral resolution were also characterized. Preliminary hyperspectral imaging results of the Rice University campus landscape, obtained with the spectrometer, are presented to demonstrate the system's spectral imaging capability for distant scenes. The spectrum of different plant species with different health conditions, obtained with the spectrometer, was in accordance with reference instrument measurements. We also imaged Houston traffic to demonstrate the system's snapshot hyperspectral imaging capability. Potential applications of the system include terrestrial monitoring, land use, air pollution, water resources, and lightning spectroscopy. The fiber-based system design potentially allows tuning between spatial and spectral sampling to meet specific imaging requirements.

A high performance, snapshot Image Mapping Spectrometer was developed that provides fast image acquisition (100 Hz) of 16 bit hyperspectral data cubes (210x210x46) over a spectral range of 515-842 nm. Essential details of the opto-mechanical design are presented. Spectral accuracy, precision, and image reconstruction metrics such as resolution are discussed. Fluorescently stained cell samples were used to directly compare the data obtained using newly developed and the reference image mapping spectrometer. Additional experimental results are provided to demonstrate the abilities of the new spectrometer to acquire highly-resolved, motion-artifact-free hyperspectral images at high temporal sampling rates.

While there have been research efforts to find faster and more efficient diagnostic techniques for tuberculosis (TB), it is equally important to monitor a patient's response to treatment over time, especially with the increasing prevalence of multi-drug resistant (MDR) and extensively-drug resistant (XDR) TB. Between sputum smear microscopy, culture, and GeneXpert, only culture can verify viability of mycobacteria. However, it may take up to six weeks to grow Mycobacterium tuberculosis (Mtb), during which time the patient may have responded to treatment or the mycobacteria are still viable because the patient has MDR or XDR TB. In both situations, treatment incurs increased patient costs and makes them more susceptible to host-drug effects such as liver damage. Coenzyme Factor 420 (F420) is a fluorescent coenzyme found naturally in mycobacteria, with an excitation peak around 420 nm and an emission peak around 470 nm. Using Mycobacterium smegmatis, we show that live and dead mycobacteria undergo different rates of photobleaching over a period of 2 min. These preliminary experiments suggest that the different photobleaching rates could be used to help monitor a patient's response to TB treatment. In future studies, we propose to describe these experiments with Mtb as both M. smegmatis and Mtb use F420.

We describe the hyperspectral Image Mapping Spectrometer (IMS) which is able to acquire spectral images of the retina with no scanning components. We then utilize this technology to obtain absolute oxygen saturation measurements in four patients with retinal diseases. The IMS acquires spatial and spectral information of a scene in a single camera exposure time. The IMS is attached to the port of a Topcon TRC-50EX funduscopic camera in order to acquire images. The IMS has high spatial (350×350) and spectral sampling (40), and avoids motion artifacts associated with eye movements. Oximetry values are obtained by measuring the absorption of retinal blood. Four patients with different retinal diseases were imaged via the IMS in this study. Oxygen saturation is calculated using a least squares fit applied to the whole blood oximetry equation. Oxygen saturation was found to be 88.6% (±1.9) and 34.1% (±7.0) for the artery and vein, respectively, in a patient with non-exudative age-related macular degeneration (AMD) with borderline glaucoma, 100.0% (±0.0) and 50.4% (±8.2) in a patient with exudative AMD, 100.0% (±0.0) and 45.2% (±7.0) in a patient with retinitis pigmentosa, and 94.1% (±2.5) and 44.9% (±5.6) in a patient with chronic iridocyclitis. These values are consistent with previously published data. Based on spatial and spectral data, we created an oxygen saturation map with oxygenation data overlying retinal vasculature. Hyperspectral imaging may be a promising way to measure retinal oxygen saturation. IMS technology is advantageous in its ability to obtain images free of motion artifacts.

We present a proof-of-principle prototype of a fiber-based snapshot spectrometer to provide high spatial and spectral sampling for biomedical application such as cell signaling or diagnostics. An image is collected by a custom fiber bundle and then divided into spatial groups with spaces in between for dispersion. The image is later scaled down by an image taper (to scale down the image size and allow smaller optical components), dispersed with a prism and captured by a CCD camera. An interpolation algorithm is used to locate each wavelength and reconstruct the image for each spectral channel. The fiber bundle is fabricated by aligning multi-mode bare fiber ribbons as matrix, gluing together in Teflon molds, laser cutting and polishing. We present preliminary finger occlusion results obtained with the spectrometer where the oxy- and deoxy-hemoglobin spectrum could be differentiated.

A miniature laser ablation probe relying on an optical fiber to deliver light requires a high coupling efficiency objective with sufficient magnification in order to provide adequate power and field for surgery. A diffraction-limited optical design is presented that utilizes high refractive index zinc sulfide to meet specifications while reducing the miniature objective down to two lenses. The design has a hypercentric conjugate plane on the fiber side and is telecentric on the tissue end. Two versions of the objective were built on a diamond lathe-a traditional cylindrical design and a custom-tapered mount. Both received an antireflective coating. The objectives performed as designed in terms of observable resolution and field of view as measured by imaging a 1951 USAF resolution target. The slanted edge technique was used to find Strehl ratios of 0.75 and 0.78, respectively, indicating nearly diffraction-limited performance. Finally, preliminary ablation experiments indicated threshold fluence of gold film was comparable to similar reported probes.

White blood cell counts have diagnostic utility in multiple diseases. A portable fluorescence microscope was developed with a disposable imaging cartridge to perform an accurate WBC count and three-part differential at the point of care.

We present the development of a 5 mm, piezo-actuated, ultrafast laser scalpel that delivers upwards of 1 μJ at the target surface. Experiments show fast and effective surface ablation of tissue tens of microns deep.

Miniature piezoelectric actuators are commonly used as a compact means to relay images for numerous endoscopic applications. These scanners normally consist of an electrically driven lead zirconate titanate (PZT) tube that oscillates an optical fiber at its resonant frequency. The diameter and length of the PZT and fiber, the attachment of the fiber to the PZT, as well as the driving signal determine the main characteristics of the scan—frequency and amplitude of vibration. We present a new, robust, and repeatable method for producing miniature PZT actuators. The described technology allows for continuous tuning of the scanner mechanical properties during the assembly stage, enabling adjustment of resonant frequency and subsequent amplitude of vibration without a priori knowledge of the fiber’s mechanical properties. The method consists of manufacturing high-precision fiber-holding plastic inserts with diamond turning lathes that allow for the fiber length to be quickly varied and locked during operation in order to meet the preferred performance. This concept of tuned PZTs was demonstrated with an imaging technique that combined two scanners oscillating in unison at the ends of a single optical fiber to relay images without the need to correlate the driving signal with a detector.

Due to the surge in the development of unmanned aerial vehicles (UAVs) and small spacecraft (CubeSats and SmallSats) in recent years, there has been a push to develop miniaturized instrumentation to be incorporated on such platforms. A compact hyperspectral imager integrated with these vehicles provides a cost-effective platform for a range of environmental sensing applications that include the monitoring of vegetation, urban development, and lightning. We present the snapshot hyperspectral imaging system (SNAP-IMS), requiring no scanning and capable of integration with a UAV. The collected hyperspectral data cube is 350 × 400 × 55 (x , y , λ) and is acquired within a single camera exposure. The system (288 mm × 150 mm × 160 mm) weighs 3.6 kg (7.9 lb), and its power consumption is marginal as there are no scanning components. Experimental testing included several flights over an area covered by diverse types of vegetation and man-made structures. Data cubes are recorded at a 1/100 s integration time, which mitigated motion-related artifacts. The low size, mass, and power consumption of the imager can enable longer and higher flights at smaller drone sizes and allow easy, portable spectral imaging. Imaging results and the system description are presented and discussed.

A 3D printing technique for manufacturing air-clad coherent fiber optic faceplates is presented. The custom G-code programming is implemented on a fused deposition modeling (FDM) desktop printer to additively draw optical fibers using high-transparency thermoplastic filaments. The 3D printed faceplate consists of 20000 fibers and achieves spatial resolution 1.78 LP/mm. Transmission loss and crosstalk are characterized and compared among the faceplates printed from four kinds of transparent filaments as well as different faceplate thicknesses. The printing temperature is verified by testing the transmission of the faceplates printed under different temperatures. Compared with the conventional stack-and-draw fabrication, the FDM 3D printing technique simplifies the fabrication procedure. The ability to draw fibers with arbitrary organization, structure and overall shape provides additional degree of freedom to opto-mechanical design. Our results indicate a promising capability of 3D printing as the manufacturing technology for fiber optical devices.

Fluorescence microscopy can be a powerful tool for cell-based diagnostic assays; however, imaging can be time consuming and labor intensive to perform. Tunable systems give the ability to electronically focus at user selected depths inside an object volume and may simplify the opto-mechanical design of the imaging system. We present a prototype of a universal, tunable, miniature fluorescence microscope built from poly(methyl methacrylate) singlets that incorporates miniature, electrowetted lenses for electronic focusing. We demonstrate the ability of this system to perform clinically relevant differential white blood cell counts using single use custom cartridges pre-loaded with the fluorescent dye acridine orange.

A number of new platforms have been developed for multiplexed bioassays that rely on imaging targeted fluorescent beads labeled with different fluorescent dyes. We developed a compact, low-cost three-dimensional printed fluorescence microscope that can be used as a detector for mutiplexed, bead-based assays to support point-of-care applications. Images obtained with the microscope were analyzed to differentiate multiple analytes in a single sample with a comparable limit of detection to commercially available macroscopic assay platforms.

A prototype miniature objective was designed and fabricated for use in a laser ablation probe utilizing a piezo scanned fiber to rapidly produce a large cutting region, improving functionality and speed for laser ablation surgery.

Three-part differential white blood cell counts are used for disease diagnosis and monitoring at the point-of-care. A low-cost, miniature fluorescent microscope was fabricated for quantification of lymphocytes, granulocytes, and monocytes in whole blood samples.

We present an analysis of the shape, surface quality, and imaging capabilities of custom 3D printed lenses. 3D printing technology enables lens prototypes to be fabricated without restrictions on surface geometry. Thus, spherical, aspherical and rotationally non-symmetric lenses can be manufactured in an integrated production process. This technique serves as a noteworthy alternative to multistage, labor-intensive, abrasive processes such as grinding, polishing and diamond turning. Here, we evaluate the quality of lenses fabricated by Luxexcel using patented Printoptical© technology that is based on an inkjet printing technique by comparing them to lenses made with traditional glass processing technologies (grinding, polishing etc.). The surface geometry and roughness of the lenses were evaluated using white-light and Fizeau interferometers. We have compared peak-to-valley wavefront deviation, root-mean-squared wavefront error, radii of curvature and the arithmetic average of the roughness profile (Ra) of plastic and glass lenses. Additionally, the imaging performance of selected pairs of lenses was tested using 1951 USAF resolution target. The results indicate performance of 3D printed optics that could be manufactured with surface roughness comparable to that of injection molded lenses (Ra < 20 nm). The RMS wavefront error of 3D printed prototypes was at a minimum 18.8 times larger than equivalent glass prototypes for a lens with a 12.7 mm clear aperture, but when measured within 63% of its clear aperture, 3D printed components' RMS wavefront error was comparable to glass lenses.

Being able to perform a white blood cell (WBC) count and differential is a crucial laboratory test for basic diagnostic practices. In this paper, we demonstrate proof of concept results for a disposable cartridge that could be used to perform a WBC count and 3-part differential at the point-of-care. The cartridge is composed of a glass slide, a layer of transfer tape, and a glass cover slip and incorporates acridine orange for cell staining and sub-type differentiation; the stained blood is then imaged, and image analysis techniques return a WBC count and 3-part differential. The cartridge was tested on a laboratory microscope with 3 normal samples, and had promising results with 85.7% of images resulting in a WBC count with ±15% of the true value. Further, the 3-part differential concentrations determined using the disposable cartridge had strong correlations with the true concentrations (R2 values of 0.9986, 0.9421, and 0.6942 for granulocytes, lymphocytes, and monocytes, respectively). Preliminary designs for a low-cost, portable microscope have been created and are currently being prototyped.

Anemia affects a quarter of the world's population, and a lack of appropriate diagnostic tools often prevents treatment in low-resource settings. Though the HemoCue 201+ is an appropriate device for diagnosing anemia in low-resource settings, the high cost of disposables ($0.99 per test in Malawi) limits its availability. We investigated using spectrophotometric measurement of blood spotted on chromatography paper as a low-cost ($0.01 per test) alternative to HemoCue cuvettes. For this evaluation, donor blood was diluted with plasma to simulate anemia, a micropipette spotted blood on paper, and a bench-top spectrophotometer validated the approach before the development of a low-cost reader. We optimized impregnating paper with chemicals to lyse red blood cells, paper type, drying time, wavelengths measured, and sensitivity to variations in volume of blood, and we validated our approach using patient samples. Lysing the blood cells with sodium deoxycholate dried in Whatman Chr4 chromatography paper gave repeatable results, and the absorbance difference between 528 nm and 656 nm was stable over time in measurements taken up to 10 min after sample preparation. The method was insensitive to the amount of blood spotted on the paper over the range of 5 μL to 25 μL. We created a low-cost, handheld reader to measure the transmission of paper cuvettes at these optimal wavelengths. Training and validating our method with patient samples on both the spectrometer and the handheld reader showed that both devices are accurate to within 2 g dL(-1) of the HemoCue device for 98% and 95% of samples, respectively.

We present the development of a 5 mm, piezo-actuated, ultrafast laser scalpel for fast tissue microsurgery. Delivery of micro-Joules level energies to the tissue was made possible by a large, 31 μm, air-cored inhibited-coupling Kagome fiber. We overcome the fiber’s low NA by using lenses made of high refractive index ZnS, which produced an optimal focusing condition with 0.23 NA objective. The optical design achieved a focused laser spot size of 4.5 μm diameter covering a 75 × 75 μm2 scan area in a miniaturized setting. The probe could deliver the maximum available laser power, achieving an average fluence of 7.8 J/cm2 on the tissue surface at 62% transmission efficiency. Such fluences could produce uninterrupted, 40 μm deep cuts at translational speeds of up to 5 mm/s along the tissue. We predicted that the best combination of speed and coverage exists at 8 mm/s for our conditions. The onset of nonlinear absorption in ZnS, however, limited the probe’s energy delivery capabilities to 1.4 μJ for linear operation at 1.5 picosecond pulse-widths of our fiber laser. Alternatives like broadband CaF2 crystals should mitigate such nonlinear limiting behavior. Improved opto-mechanical design and appropriate material selection should allow substantially higher fluence delivery and propel such Kagome fiber-based scalpels towards clinical translation.

Three-part differential white blood cell counts are used for disease diagnosis and monitoring at the point-of-care. A low-cost, miniature achromatic microscope was fabricated for identification of lymphocytes, monocytes, and granulocytes in samples of whole blood stained with acridine orange. The microscope was manufactured using rapid prototyping techniques of diamond turning and 3D printing and is intended for use at the point-of-care in low-resource settings. The custom-designed microscope requires no manual adjustment between samples and was successfully able to classify three white blood cell types (lymphocytes, granulocytes, and monocytes) using samples of peripheral whole blood stained with acridine orange.

We demonstrate a miniature, tunable, minimally invasive endoscope for diagnosis of the auditory system. The probe is designed to sharply image anatomical details of the middle ear without the need for physically adjusting the position of the distal end of the endoscope. This is achieved through the addition of an electrowetted, tunable, electronically-controlled lens to the optical train. Morphological imaging is enabled by scanning light emanating from an optical coherence tomography system. System performance was demonstrated by imaging part of the ossicular chain and wall of the middle ear cavity of a normal mouse. During the experiment, we electronically moved the plane of best focus from the incudo-stapedial joint to the stapedial artery. Repositioning the object plane allowed us to image anatomical details of the middle ear beyond the depth of field of a static optical system. We also demonstrated for the first time to our best knowledge, that an optical system with an electrowetted, tunable lens may be successfully employed to measure sound-induced vibrations within the auditory system by measuring the vibratory amplitude of the tympanic membrane in a normal mouse in response to pure tone stimuli.