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Efficient cryogenic near-infrared Tm:YLF laser

June 12, 2017
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Journal Article
Author:
Christopher E. Aleshire
…
Published in:
Opt. Express, Vol. 25, No. 12, 12 June 2017, 13408.
Topic:
optics
R&D area:
R&D group:

Summary

Operation of a cw thulium laser emitting at 816 nm has been demonstrated in bulk Tm:YLF with 46% slope efficiency. Prior cw demonstrations of this transition have been limited to ZBLAN fiber hosts and prior lasing in bulk crystalline host material has been limited to quasi-cw operation due to population trapping. Trapping at the 3F4 level was mitigated by co-lasing at 1876 nm. The co-lasing technique should be applicable to room-temperature operation and to power scaling of YLF and other crystal hosts.
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Summary

Operation of a cw thulium laser emitting at 816 nm has been demonstrated in bulk Tm:YLF with 46% slope efficiency. Prior cw demonstrations of this transition have been limited to ZBLAN fiber hosts and prior lasing in bulk crystalline host material has been limited to quasi-cw operation due to population...

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Efficient cryogenic near-infrared Tm:YLF laser

Fluidic microoptics with adjustable focusing and beam steering for single cell optogenetics

June 10, 2017
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Journal Article
Author:
Shaun R. Berry
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Published in:
Opt. Express, Vol. 25, No. 14, 10 July 2017, pp. 16825-16839.
Topic:
optics
R&D area:
R&D group:

Summary

Electrically controlled micron-scale liquid lenses have been designed, fabricated and demonstrated, that provide both adjustable focusing and beam steering, with the goal of applying them to optogenetic in vivo mapping of brain activity with single cell resolution. The liquid lens is formed by the interface between two immiscible liquids which are contained in a conically tapered lens cavity etched into a fused silica substrate. Interdigitated electrodes have been patterned along the sidewall of the taper to control the liquid lens curvature and tilt. Microlenses with apertures ranging in size from 30 to 80 μm were fabricated and tunable focusing ranging from 0.25 to 3 mm and beam steering of ± 1 degree have been demonstrated.
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Summary

Electrically controlled micron-scale liquid lenses have been designed, fabricated and demonstrated, that provide both adjustable focusing and beam steering, with the goal of applying them to optogenetic in vivo mapping of brain activity with single cell resolution. The liquid lens is formed by the interface between two immiscible liquids which...

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Fluidic microoptics with adjustable focusing and beam steering for single cell optogenetics

Use of mass spectrometric vapor analysis to improve canine explosive detection efficiency

June 9, 2017
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Journal Article
Author:
Ta-Hsuan Ong
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Published in:
Anal. Chem., Vol. 89, 9 June 2017, 6482-90.
Topic:
detection systems
R&D area:
R&D group:

Summary

Canines remain the gold standard for explosives detection in many situations, and there is an ongoing desire for them to perform at the highest level. This goal requires canine training to be approached similarly to scientific sensor design. Developing a canine training regimen is made challenging by a lack of understanding of the canine's odor environment, which is dynamic and typically contains multiple odorants. Existing methodology assumes that the handler's intention is an adequate surrogate for actual knowledge of the odors cuing the canine, but canines are easily exposed to unintentional explosive odors through training material cross-contamination. A sensitive, real-time (~1 s) vapor analysis mass spectrometer was developed to provide tools, techniques, and knowledge to better understand, train, and utilize canines. The instrument has a detection library of nine explosives and explosive-related materials consisting of 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 2,4,6-trinitrotoluene (TNT), nitroglycerin (NG), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), pentaerythritol tetranitrate (PETN), triacetone triperoxide (TATP), hexamethylene triperoxide diamine (HMTD), and cyclohexanone, with detection limits in the parts-per-trillion to parts-per-quadrillion range by volume. The instrument can illustrate aspects of vapor plume dynamics, such as detecting plume filaments at a distance. The instrument was deployed to support canine training in the field, detecting cross-contamination among training materials, and developing an evaluation method based on the odor environment. Support for training material production and handling was provided by studying the dynamic headspace of a nonexplosive HMTD training aid that is in development. These results supported existing canine training and identified certain areas that may be improved.
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Summary

Canines remain the gold standard for explosives detection in many situations, and there is an ongoing desire for them to perform at the highest level. This goal requires canine training to be approached similarly to scientific sensor design. Developing a canine training regimen is made challenging by a lack of...

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Use of mass spectrometric vapor analysis to improve canine explosive detection efficiency

Open-source, community-driven microfluidics with Metafluidics

June 7, 2017
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Journal Article
Author:
David S. Kong
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Published in:
Nat. Biotechnol., Vol. 35, No. 6, 7 June 2017, pp. 523-9.
Topic:
microfluidics
R&D area:
R&D group:

Summary

Microfluidic devices have the potential to automate and miniaturize biological experiments, but open-source sharing of device designs has lagged behind sharing of other resources such as software. Synthetic biologists have used microfluidics for DNA assembly, cell-free expression, and cell culture, but a combination of expense, device complexity, and reliance on custom set-ups hampers their widespread adoption. We present Metafluidics, an open-source, community-driven repository that hosts digital design files, assembly specifications, and open-source software to enable users to build, configure, and operate a microfluidic device. We use Metafluidics to share designs and fabrication instructions for both a microfluidic ring-mixer device and a 32-channel tabletop microfluidic controller. This device and controller are applied to build genetic circuits using standard DNA assembly methods including ligation, Gateway, Gibson, and Golden Gate. Metafluidics is intended to enable a broad community of engineers, DIY enthusiasts, and other nontraditional participants with limited fabrication skills to contribute to microfluidic research.
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Summary

Microfluidic devices have the potential to automate and miniaturize biological experiments, but open-source sharing of device designs has lagged behind sharing of other resources such as software. Synthetic biologists have used microfluidics for DNA assembly, cell-free expression, and cell culture, but a combination of expense, device complexity, and reliance on...

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Open-source, community-driven microfluidics with Metafluidics

Re-engineering Artificial Muscle with Microhydraulics

June 5, 2017
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Journal Article
Author:
Jakub T. Kedzierski
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Published in:
Nature Microsystems & Nanoengineering, vol. 3
Topic:
microfluidics
R&D area:
R&D group:

Summary

We introduce a new type of actuator, the microhydraulic stepping actuator (MSA), which borrows design and operational concepts from biological muscle and stepper motors. MSAs offer a unique combination of power, efficiency, and scalability not easily achievable on the microscale. The actuator works by integrating surface tension forces produced by electrowetting acting on scaled droplets along the length of a thin ribbon. Like muscle, MSAs have liquid and solid functional components and can displace a large
fraction of their length. The 100 μm pitch MSA presented here already has an output power density of over 200 W kg− 1, rivaling the most powerful biological muscles, due to the scaling of surface tension forces, MSA’s power density grows quadratically as its dimensions are reduced.
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Summary

We introduce a new type of actuator, the microhydraulic stepping actuator (MSA), which borrows design and operational concepts from biological muscle and stepper motors. MSAs offer a unique combination of power, efficiency, and scalability not easily achievable on the microscale. The actuator works by integrating surface tension forces produced by...

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Re-engineering Artificial Muscle with Microhydraulics

Aircraft laser strike geolocation system

June 5, 2017
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Conference Paper
Author:
Erin M. Tomlinson
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Published in:
17th AIAA Aviation Technology, Integration, and Operations Conf., 5-9 June 2017.
Topic:
detection systems
R&D area:
R&D group:

Summary

Laser strikes against aircraft are increasing at an alarming rate, driven by the availability of cheap powerful lasers and a lack of deterrence due to the challenges of locating and apprehending perpetrators. Although window coatings and pilot goggles effectively block laser light, uptake has been low due to high cost and pilot reluctance. This paper describes the development and testing of a proof-of-concept ground based sensor system to rapidly geolocate the origin of a laser beam in a protected region of airspace and disseminate this information to law enforcement to allow a timely and targeted response. Geolocation estimates with accuracies of better than 20 m have been demonstrated within 30 seconds of an event at a range of 8.9 nmi with a 450 mW laser. Recommendations for an operational prototype at an airport are also described.
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Summary

Laser strikes against aircraft are increasing at an alarming rate, driven by the availability of cheap powerful lasers and a lack of deterrence due to the challenges of locating and apprehending perpetrators. Although window coatings and pilot goggles effectively block laser light, uptake has been low due to high cost...

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Aircraft laser strike geolocation system

A polarization technique for mitigating low-grazing-angle radar sea clutter

June 4, 2017
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Conference Paper
Author:
Molly K. Crane
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Published in:
IEEE Int. Microwave Symp., 4-9 June 2017.
Topic:
radar
R&D area:
R&D group:

Summary

Traditional detection schemes in conventional maritime surveillance radars may suffer serious performance degradation due to sea clutter, particularly in low-grazing-angle (LGA) geometries. In such geometries, typical statistical assumptions regarding sea clutter backscatter do not hold. Trackers can be overwhelmed by false alarms, while objects of interest can be challenging to detect. Despite several decades of attempts to devise a means of mitigating the effects of LGA sea clutter on traditional detection schemes, minimal progress has been made in developing an approach that is both robust and practical. To supplement work exploring whether polarization information might offer an effective means of enhancing target detection in sea clutter, MIT Lincoln Laboratory (MIT LL) collected a fully polarimetric X-band radar dataset on the Atlantic coast of Massachusetts Cape Ann in October 2015. Leveraging this dataset, MIT LL developed Polarimetric Co-location Layering (PCL), an algorithm that uses a fundamental polarimetric characteristic of sea clutter to retain detections on objects of interest while reducing the number of false alarms in a conventional singlepolarization radar by as many as two orders of magnitude. PCL is robust across waveform bandwidths, pulse repetition frequencies, and sea states. Moreover, PCL is practical: It can plug directly into the standard radar signal processing chain.
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Summary

Traditional detection schemes in conventional maritime surveillance radars may suffer serious performance degradation due to sea clutter, particularly in low-grazing-angle (LGA) geometries. In such geometries, typical statistical assumptions regarding sea clutter backscatter do not hold. Trackers can be overwhelmed by false alarms, while objects of interest can be challenging to...

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A polarization technique for mitigating low-grazing-angle radar sea clutter

Report on the 2016 CoSPA and Traffic Flow Impact operational demonstration

June 1, 2017
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Project Report
Author:
Joseph C. Venuti
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Published in:
MIT Lincoln Laboratory Report ATC-433
Topic:
weather
R&D area:
R&D group:

Summary

This technical report summarizes the operational observations recorded by MIT Lincoln Laboratory (MIT LL) aviation subject matter experts during the period 1 June to 31 October 2016. The MIT LL observation team visited three Federal Aviation Administration (FAA) Air Route Traffic Control Centers (ARTCC) and the Air Traffic Control System Command Center (ATCSCC) on three separate convective events covering four days during the summer of 2016. Five commercial airlines were also involved in the observations. Specifically noted were the utilization of the deterministic convective weather forecasting model, Storm Prediction for Aviation (CoSPA), and a newly developed decision support application, Traffic Flow Impact (TFI). These field evaluations were supported via the FAA AJM-334 program.
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Summary

This technical report summarizes the operational observations recorded by MIT Lincoln Laboratory (MIT LL) aviation subject matter experts during the period 1 June to 31 October 2016. The MIT LL observation team visited three Federal Aviation Administration (FAA) Air Route Traffic Control Centers (ARTCC) and the Air Traffic Control System...

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Report on the 2016 CoSPA and Traffic Flow Impact operational demonstration

Germanium CCDs for large-format SWIR and x-ray imaging

May 25, 2017
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Journal Article
Author:
Christopher W. Leitz
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Published in:
J. Instrum., Vol. 12, No. 5, May 2017, C05014.
Topic:
photonics
R&D area:
R&D group:

Summary

Germanium exhibits high sensitivity to short-wave infrared (SWIR) and X-ray radiation, making it an interesting candidate for imaging applications in these bands. Recent advances in germanium processing allow for high-quality charge-coupled devices (CCDs) to be realized in this material. In this article, we discuss our evaluation of germanium as an absorber material for CCDs via fabrication and analysis of discrete devices such as diodes, metal-insulator-semiconductor capacitors, and buried-channel metal-oxide-semiconductor field-effect transistors (MOSFETs). We then describe fabrication of our first imaging device on germanium, a 32 x 1 x 8.1 um linear shift register. Based on this work, we find that germanium is a promising material for CCDs imaging in the SWIR and X-ray bands.
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Summary

Germanium exhibits high sensitivity to short-wave infrared (SWIR) and X-ray radiation, making it an interesting candidate for imaging applications in these bands. Recent advances in germanium processing allow for high-quality charge-coupled devices (CCDs) to be realized in this material. In this article, we discuss our evaluation of germanium as an...

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Germanium CCDs for large-format SWIR and x-ray imaging

Raman Detection of a Single Airborne Aerosol Particles of Isovanillin(3.09 MB)

May 24, 2017
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Journal Article
Author:
Roshan L. Aggarwal
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Published in:
AIP Advances, vol. 7, no. 5
Topic:
chemical technologies
R&D area:
R&D group:

Summary

Raman spectroscopy of trapped single aerosol particles has been reported previously. However, detection of single aerosol particles via Raman spectroscopy in a flowing system has not been yet reported. In this paper, we describe the first detection of single 3 um flowing airborne aerosol particles flowing through a Raman system, which is a simplified version of the previously reported system with a 532-nm, 10W cw double-pass laser, 532-nm isolator, and double-sided collection optics. The current system has single-pass laser, no 532-nm isolator, and single-sided collection optics. Previous Raman detection of single aerosol particles has been made using trapped particles.
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Summary

Raman spectroscopy of trapped single aerosol particles has been reported previously. However, detection of single aerosol particles via Raman spectroscopy in a flowing system has not been yet reported. In this paper, we describe the first detection of single 3 um flowing airborne aerosol particles flowing through a Raman system...

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Raman Detection of a Single Airborne Aerosol Particles of Isovanillin
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