Sequentially timed all-optical mapping photography (STAMP)

Nakagawa, Keiichi; Iwasaki, Atsushi; Oishi, Yuji; Horisaki, Ryoichi; Tsukamoto, Akira; Nakamura, Aoi; Hirosawa, Kenichi; Liao, Hongen; Ushida, Takashi; Goda, Keisuke; Kannari, Fumihiko; Sakuma, Ichiro

doi:10.1038/nphoton.2014.163

Cited by 270 publications

(152 citation statements)

References 26 publications

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“…The unique one-to-one mapping between space and wavelength is achieved by using diffractive optical elements, such as a diffraction grating for 1D imaging [2] and the joint use of a virtually imaged phased array (VIPA) and a diffraction grating for 2D imaging [3]. SEI technique has attracted considerable research interests due to its features of wide options of illumination wavelength beyond visible light [4], and a great number of resolvable points [5]. However, one difficulty associated with the SEI approach is the poor temporal resolution, which is mainly due to the limited speed in wavelength tuning or spectrum measurement.…”

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confidence: 99%

Highly efficient spectrally encoded imaging using a 45° tilted fiber grating

Wang

Yan

et al. 2016

Opt. Lett.

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A novel highly efficient, fiber-compatible spectrally encoded imaging (SEI) system using a 45° tilted fiber grating (TFG) is proposed and experimentally demonstrated for the first time. The TFG serves as an infiber lateral diffraction element, eliminating the need for bulky and lossy free-space diffraction gratings in conventional SEI systems. Under proper polarization control, due to the strong tilted reflection, the 45° TFG offers a diffraction efficiency as high as 93.5%. Our new design significantly reduces the volume of the SEI system, improves energy efficiency and system stability. As a proof-of-principle experiment, spectrally encoded imaging of a customer-designed sample (9.6 mm × 3.0 mm) using the TFG-based system is demonstrated. The lateral resolution of the SEI system is measured to be 42 m in our experiment

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confidence: 99%

Highly efficient spectrally encoded imaging using a 45° tilted fiber grating

Wang

Yan

et al. 2016

Opt. Lett.

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“…The identification most often was only possible after a detailed review of the complete recording sequences and was based as much on details of the birds in the images with sufficient definition as on the flight patterns observed in the sequence as a whole. Modern cameras can record up to 4.4 trillion FPS (Nakagawa et al, 2014) and 7,580 × 4,320 pixel cameras also exist on the market (e.g., WEAPON 8K S35) for very specific applications, but they have limited recording capacity in terms of recording time due to the data volume generated. In this trade-off between recording speed and image quality, it is probable that, in the near future, cameras capable of 480 FPS and 4,096 × 2,160 pixels may be available at affordable prices for applications such as, our study.…”

Section: Discussionmentioning

confidence: 99%

On-Board Video Recording Unravels Bird Behavior and Mortality Produced by High-Speed Trains

et al. 2017

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Large high-speed railway (HSR) networks are planned for the near future to accomplish increased transport demand with low energy consumption. However, high-speed trains produce unknown avian mortality due to birds using the railway and being unable to avoid approaching trains. Safety and logistic difficulties have precluded until now mortality estimation in railways through carcass removal, but information technologies can overcome such problems. We present the results obtained with an experimental on-board system to record bird-train collisions composed by a frontal recording camera, a GPS navigation system and a data storage unit. An observer standing in the cabin behind the driver controlled the system and filled out a form with data of collisions and bird observations in front of the train. Photographs of the train front taken before and after each journey were used to improve the record of killed birds. Trains running the 321.7 km line between Madrid and Albacete (Spain) at speeds up to 250-300 km/h were equipped with the system during 66 journeys along a year, totaling approximately 14,700 km of effective recording. The review of videos produced 1,090 bird observations, 29.4% of them corresponding to birds crossing the infrastructure under the catenary and thus facing collision risk. Recordings also showed that 37.7% bird crossings were of animals resting on some element of the infrastructure moments before the train arrival, and that the flight initiation distance of birds (mean ± SD) was between 60 ± 33 m (passerines) and 136 ± 49 m (raptors). Mortality in the railway was estimated to be 60.5 birds/km year on a line section with 53 runs per day and 26.1 birds/km year in a section with 25 runs per day. Our results are the first published estimation of bird mortality in a HSR and show the potential of information technologies to yield useful data for monitoring the impact of trains on birds via on-board recording systems. Moreover, recordings point to the use of the infrastructure by birds as a key issue leading to bird train-kill.

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“…[9][10][11][12] Shock-induced transformations can include defect formation, fracture, phase transitions and chemical reactions whose spatial locations and extents in an image can reveal material properties and dynamics. 5,10,13,14 The combination of ultrafast imaging methods that capture spatially varying material responses with advanced image processing algorithms that reliably define the different regions under observation can further our understanding of complex shock-induced responses. 5,10,13,[15][16][17][18][19][20][21] In the field of shock physics, many images are manually segmented to extract material features from images.…”

Section: ~ 2 ~mentioning

confidence: 99%

“…5,10,13,14 The combination of ultrafast imaging methods that capture spatially varying material responses with advanced image processing algorithms that reliably define the different regions under observation can further our understanding of complex shock-induced responses. 5,10,13,[15][16][17][18][19][20][21] In the field of shock physics, many images are manually segmented to extract material features from images. Most image analysis uses Fourier filtering, which suppresses high-frequency noise, but also diminishes the high-frequency features inherent to shock waves.…”

Section: ~ 2 ~mentioning

confidence: 99%

Machine learning to analyze images of shocked materials for precise and accurate measurements

Dresselhaus-Cooper

Howard

Hock

et al. 2017

Journal of Applied Physics

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A supervised machine learning algorithm, called locally adaptive discriminant analysis (LADA), has been developed to locate boundaries between identifiable image features that have varying intensities. LADA is an adaptation of image segmentation, which includes techniques that find the positions of image features (classes) using statistical intensity distributions for each class in the image. In order to place a pixel in the proper class, LADA considers the intensity at that pixel and the distribution of intensities in local (nearby) pixels. This paper presents the use of LADA to provide, with statistical uncertainties, the positions and shapes of features within ultrafast images of shock waves. We demonstrate the ability to locate image features including crystals, density changes associated with shock waves, and material jetting caused by shock waves. This algorithm can analyze images that exhibit a wide range of physical phenomena because it does not rely on comparison to a model. LADA enables analysis of images from shock physics with statistical rigor independent of underlying models or simulations.

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Sequentially timed all-optical mapping photography (STAMP)

Cited by 270 publications

References 26 publications

Highly efficient spectrally encoded imaging using a 45° tilted fiber grating

Highly efficient spectrally encoded imaging using a 45° tilted fiber grating

On-Board Video Recording Unravels Bird Behavior and Mortality Produced by High-Speed Trains

Machine learning to analyze images of shocked materials for precise and accurate measurements

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