High-speed camera

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A high-speed camera is a device capable of capturing moving images with exposures of less than ⁠1/1 000⁠ second or frame rates in excess of 250 frames per second. [1] It is used for recording fast-moving objects as photographic images onto a storage medium. After recording, the images stored on the medium can be played back in slow motion. Early high-speed cameras used photographic film to record the high-speed events, but have been superseded by entirely electronic devices using an image sensor (e.g. a charge-coupled device (CCD) or a MOS active pixel sensor (APS)), typically recording over 1 000 frames per second onto DRAM, to be played back slowly to study the motion for scientific study of transient phenomena. [2]

Contents

Overview

A high-speed camera can be classified as:

  1. A high-speed film camera which records to film,
  2. A high-speed video camera which records to electronic memory,
  3. A high-speed framing camera which records images on multiple image planes or multiple locations on the same image plane [3] (generally film or a network of CCD cameras),
  4. A high-speed streak camera which records a series of line-sized images to film or electronic memory.

A normal motion picture film is played back at 24 frames per second, while television uses 25 frames/s (PAL) or 29.97 frames/s (NTSC). High-speed film cameras can film up to a quarter of a million fps by running the film over a rotating prism or mirror instead of using a shutter, thus reducing the need for stopping and starting the film behind a shutter which would tear the film stock at such speeds. Using this technique one second of action can be stretched to more than ten minutes of playback time (super slow motion). High-speed video cameras are widely used for scientific research, [4] [5] military test and evaluation, [6] and industry. [7] Examples of industrial applications are filming a manufacturing line to better tune the machine, or in the car industry filming a crash test to investigate the effect on the crash dummy passengers and the automobile. Today, the digital high-speed camera has replaced the film camera used for Vehicle Impact Testing. [8]

Schlieren video of an intermediate ballistic event of a shotshell cartridge. Nathan Boor, Aimed Research.

Television series such as MythBusters and Time Warp often use high-speed cameras to show their tests in slow motion. Saving the recorded high-speed images can be time-consuming because as of 2017, consumer cameras have resolutions up to four megapixels with frame rates of over 1,000 per second which will record at a rate of 11 gigabytes per second. Technologically these cameras are very advanced, yet saving images requires use of slower standard video-computer interfaces. [9] While recording is very fast, saving images is considerably slower. To reduce the storage space required and the time required for people to examine a recording, only the parts of an action which are of interest or relevance can be selected to film. When recording a cyclical process for industrial breakdown analysis, only the relevant part of each cycle is filmed.

A problem for high-speed cameras is the needed exposure for the film; very bright light is needed to be able to film at 40,000  fps, sometimes leading to the subject of examination being destroyed because of the heat of the lighting. Monochromatic (black and white) filming is sometimes used to reduce the light intensity required. Even higher speed imaging is possible using specialized electronic charge-coupled device (CCD) imaging systems, which can achieve speeds of over 25 million fps. These cameras, however, still use rotating mirrors, like their older film counterparts. Solid state cameras can achieve speeds of up to 10 million fps. [10] [11] All development in high-speed cameras is now focused on digital video cameras which have many operational and cost benefits over film cameras.

In 2010 researchers built a camera exposing each frame for two trillionths of a second (picoseconds), for an effective frame rate of half a trillion fps (femto-photography). [12] [13] Modern high-speed cameras operate by converting the incident light (photons) into a stream of electrons which are then deflected onto a photoanode, back into photons, which can then be recorded onto either film or CCD.

Uses in television

Uses in science

High-speed cameras are frequently used in science in order to characterize events which happen too fast for traditional film speeds. Biomechanics employs such cameras to capture high-speed animal movements, such as jumping by frogs and insects, [15] suction feeding in fish, the strikes of mantis shrimp, and the aerodynamic study of pigeons' helicopter-like movements [16] using motion analysis of the resulting sequences from one or more cameras to characterize the motion in either 2-D or 3-D.

The move from film to digital technology has greatly reduced the difficulty in use of these technologies with unpredictable behaviors, specifically via the use of continuous recording and post-triggering. With film high-speed cameras, an investigator must start the film then attempt to entice the animal to perform the behavior in the short time before the film runs out, resulting in many useless sequences where the animal behaves too late or not at all. In modern digital high-speed cameras, [17] the camera can simply record continuously as the investigator attempts to elicit the behavior, following which a trigger button will stop the recording and allow the investigator to save a given time interval before and after the trigger (determined by frame rate, image size and memory capacity during continuous recording). Most software allows saving a subset of recorded frames, minimizing file size issues by eliminating useless frames before or after the sequence of interest. Such triggering can also be used to synchronize recording across multiple cameras.

The explosion of alkali metals on contact with water has been studied using a high-speed camera. Frame-by-frame analysis of a sodium/potassium alloy exploding in water, combined with molecular dynamic simulations, suggested that the initial expansion may be the result of a Coulomb explosion and not combustion of hydrogen gas as previously thought. [18]

Digital high-speed camera footage has strongly contributed to the understanding of lightning when combined with electric field measuring instrumentation and sensors which can map the propagation of lightning leaders through the detection of radio waves generated by this process. [19]

Uses in industry

When moving from reactive maintenance to predictive maintenance, it is crucial that breakdowns are really understood. One of the basic analysis techniques is to use high-speed cameras in order to characterize events which happen too fast to see, e.g. during production. Similar to use in science, with a pre- or post-triggering capability the camera can simply record continuously as the mechanic waits for the breakdown to happen, following which a trigger signal (internal or external) will stop the recording and allow the investigator to save a given time interval prior to the trigger (determined by frame rate, image size, and memory capacity during continuous recording). Some software allows viewing the issues in real time, by displaying only a subset of recorded frames, minimizing file size and watch time issues by eliminating useless frames before or after the sequence of interest.

High-speed video cameras are used to augment other industrial technologies such as x-ray radiography. When used with the proper phosphor screen which converts x-rays into visible light, high-speed cameras can be used to capture high-speed x-ray videos of events inside mechanical devices and biological specimens. The imaging speed is mainly limited by the phosphor screen decay rate and intensity gain which has a direct relationship on the camera's exposure. Pulsed x-ray sources limit frame rate and should be properly synchronized with camera frame captures. [20]

Uses in warfare

In 1950 Morton Sultanoff, a physicist for the U.S. Army at Aberdeen Proving ground, invented a super high-speed camera that took frames at one-millionth of a second, and was fast enough to record the shock wave of a small explosion. [21] High Speed digital cameras have been used to study how mines dropped from the air will deploy in near-shore regions, [22] including development of various weapon systems. In 2005 high speed digital cameras with 4 megapixel resolution, recording at 1500 fps, were replacing the 35mm and 70mm high speed film cameras used on tracking mounts on test ranges that capture ballistic intercepts. [23]

See also

Related Research Articles

<span class="mw-page-title-main">Digital video</span> Digital electronic representation of moving visual images

Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data. This is in contrast to analog video, which represents moving visual images in the form of analog signals. Digital video comprises a series of digital images displayed in rapid succession, usually at 24, 25, 30, or 60 frames per second. Digital video has many advantages such as easy copying, multicasting, sharing and storage.

Frame rate, most commonly expressed in frames per second or FPS, is typically the frequency (rate) at which consecutive images (frames) are captured or displayed. This definition applies to film and video cameras, computer animation, and motion capture systems. In these contexts, frame rate may be used interchangeably with frame frequency and refresh rate, which are expressed in hertz. Additionally, in the context of computer graphics performance, FPS is the rate at which a system, particularly a GPU, is able to generate frames, and refresh rate is the frequency at which a display shows completed frames. In electronic camera specifications frame rate refers to the maximum possible rate frames could be captured, but in practice, other settings may reduce the actual frequency to a lower number than the frame rate.

<span class="mw-page-title-main">Camera</span> Optical device for recording images

A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photography and videography, cameras have played a significant role in the progression of visual arts, media, entertainment, surveillance, and scientific research. The invention of the camera dates back to the 19th century and has since evolved with advancements in technology, leading to a vast array of types and models in the 21st century.

<span class="mw-page-title-main">Telecine</span> Process for broadcasting content stored on film stock

Telecine is the process of transferring film into video and is performed in a color suite. The term is also used to refer to the equipment used in this post-production process.

<span class="mw-page-title-main">Cinematography</span> Art of motion picture photography

Cinematography is the art of motion picture photography.

<span class="mw-page-title-main">Slow motion</span> Effect in film-making

Slow motion is an effect in film-making whereby time appears to be slowed down. It was invented by the Austrian priest August Musger in the early 20th century. This can be accomplished through the use of high-speed cameras and then playing the footage produced by such cameras at a normal rate like 30 fps, or in post production through the use of software.

<span class="mw-page-title-main">Time-lapse photography</span> Film technique where the frame rate is lower than that used to view the sequence

Time-lapse photography is a technique in which the frequency at which film frames are captured is much lower than the frequency used to view the sequence. When played at normal speed, time appears to be moving faster and thus lapsing. For example, an image of a scene may be captured at 1 frame per second but then played back at 30 frames per second; the result is an apparent 30 times speed increase. Similarly, film can also be played at a much lower rate than at which it was captured, which slows down an otherwise fast action, as in slow motion or high-speed photography.

<span class="mw-page-title-main">Digital cinematography</span> Digital image capture for film

Digital cinematography is the process of capturing (recording) a motion picture using digital image sensors rather than through film stock. As digital technology has improved in recent years, this practice has become dominant. Since the 2000s, most movies across the world have been captured as well as distributed digitally.

<span class="mw-page-title-main">Photo finish</span> Method for determining winner of races

A photo finish occurs in a sporting race when multiple competitors cross the finishing line at nearly the same time. As the naked eye may not be able to determine which of the competitors crossed the line first, a photo or video taken at the finish line may be used for a more accurate check. Photo finishes make it less likely that officials will declare a race a dead heat.

<span class="mw-page-title-main">High-speed photography</span> Photography genre

High-speed photography is the science of taking pictures of very fast phenomena. In 1948, the Society of Motion Picture and Television Engineers (SMPTE) defined high-speed photography as any set of photographs captured by a camera capable of 69 frames per second or greater, and of at least three consecutive frames. High-speed photography can be considered to be the opposite of time-lapse photography.

High-motion is the characteristic of video or film footage displayed possessing a sufficiently high frame rate that moving images do not blur or strobe even when tracked closely by the eye. The most common forms of high motion are NTSC and PAL video at their native display rates. Movie film does not portray high motion even when shown on television monitors.

<span class="mw-page-title-main">Burst mode (photography)</span> Shooting mode in still camera

Burst mode, also called continuous shooting mode, sports mode, continuous mode, or burst shot, is a shooting mode in still cameras where several photos are captured in quick succession by either pressing the shutter button or holding it down. This is used mainly when the subject is in successive motion, such as sports photography. The photographer can then select the best image of the group or arrange them in a sequence to study the transitions in detail.

<span class="mw-page-title-main">Strip photography</span> Type of photographic technique

Strip photography, or slit photography, is a photographic technique of capturing a two-dimensional image as a sequence of one-dimensional images over time, in contrast to a normal photo which is a single two-dimensional image at one point in time. A moving scene is recorded, over a period of time, using a camera that observes a narrow strip rather than the full field. If the subject is moving through this observed strip at constant speed, they will appear in the finished photo as a visible object. Stationary objects, like the background, will be the same the whole way across the photo and appear as stripes along the time axis; see examples on this page.

In motion picture technology—either film or video—high frame rate (HFR) refers to higher frame rates than typical prior practice.

<span class="mw-page-title-main">Photron</span>

Photron is an international company that manufactures high-speed digital cameras based in Tokyo, Japan, with offices in San Diego, California and the United Kingdom.

<span class="mw-page-title-main">FASTCAM Super 10K</span> Camera model

The Photron FASTCAM Super 10K is a 512 x 480 High-speed camera. It is part of the Photron FASTCAM line of cameras, introduced in 1996. Photron FASTCAM Super 10k was introduce in 2000. However, the camera was trade branded previously in 1992 as a KODAK MASD product. The Kodak Motioncorder and the Photron FASTCAM Super 10K are the same camera, just different trade names.

<span class="mw-page-title-main">FASTCAM SE</span> Type of high-speed camera

The Photron FASTCAM SE is a 256 x 256 High-speed camera. It is part of the Photron FASTCAM line of cameras, introduced in 1996. Photron FASTCAM SE was introduce in 2000. However, the camera was trade branded previously in 1992 as a KODAK MASD product. The Kodak HS4540 and the Photron SE are the same camera, just different trade names.

<span class="mw-page-title-main">FASTCAM Spectra</span> Camera model

The Photron FASTCAM SPECTRA is a 256 x 256 High-speed camera coupled with an image intensifier. The image intensifier can shutter to 20 nanoseconds and has a spectral response between 180 nm to 800 nm. It is part of the Photron FASTCAM line of cameras, introduced in 1998.

<span class="mw-page-title-main">EktaPro Motioncorder</span> Camera model

The KODAK Motioncorder is a 512 x 480 High-speed camera. It is part of the Photron FASTCAM line of cameras, introduced in 1996. Photron Kodak Motioncorder was introduce in 1996. The camera was manufacture by Photron but trade branded as a KODAK MASD product. The Kodak Motioncorder and the Photron FASTCAM Super 10K Motioncorder are the same camera, just different trade names.

<span class="mw-page-title-main">FASTCAM Ultima 512</span> Camera model

The Photron FASTCAM Ultima 512 is a 512 × 512 high-speed camera. It is part of the Photron FASTCAM line of cameras. The Photron FASTCAM Ultima 512 was introduced in 2001.

References

  1. ↑ Journal of the Society of Motion Picture Engineers: High-Speed Photography, Preface p.5, Mar 1949
  2. ↑ "High Frame Rate Electronic Imaging" (PDF). Archived from the original (PDF) on 2016-03-04. Retrieved 2010-03-07.
  3. ↑ "High-Speed Camera Tutorials".
  4. ↑ scientific research Chen, Xianfeng (2012). "Effect of CH4–Air Ratios on Gas Explosion Flame Microstructurec and Propagation Behaviors". Energies. 5 (10): 4132–4146. doi: 10.3390/en5104132 .
  5. ↑ scientific researchAnderson, Christopher V. (2010). "Ballistic tongue projection in chameleons maintains high performance at low temperature" (PDF). Proceedings of the National Academy of Sciences. 107 (12): 5495–5499. Bibcode:2010PNAS..107.5495A. doi: 10.1073/pnas.0910778107 . PMC   2851764 . PMID   20212130 . Retrieved 2 February 2010.
  6. ↑ Chu, Dr. Peter C. (4 May 2006). "Non-Cylindrical Mine Drop Experiment" (PDF). Seventh International Symposium on Technology and Mine Problem, NPS, Monterey, California, USA.
  7. ↑ "Photron Camera Honored by Japan Society of Mechanical Engineers". Quality Magazine. Retrieved January 23, 2008.
  8. ↑ "Replacing 16 mm Film Cameras with High Definition Digital Cameras" (PDF). Archived from the original (PDF) on 2016-09-11. Retrieved 2010-03-07.
  9. ↑ REVIEW: High Speed Cameras, Jan. 4, 2011
  10. ↑ "Hyper Vision HPV-X2".
  11. ↑ Brandaris 128: A digital 25 million frames per second camera with 128 highly sensitive frames
  12. ↑ Velten, Andreas; Lawson, Everett; Bardagjy, Andrew; Bawendi, Moungi; Raskar, Ramesh (2011-12-13). "Slow art with a trillion frames per second camera". ACM SIGGRAPH 2011 Posters. Web.media.mit.edu. p. 1. doi:10.1145/2037715.2037730. ISBN   9781450309714. S2CID   9641010 . Retrieved 2012-10-04. Work supported by research grants in 2009 and 2010.
  13. ↑ Velten, Andreas; Di Wu; Adrian Jarabo; Belen Masia; Christopher Barsi; Chinmaya Joshi; Everett Lawson; Moungi Bawendi; Diego Gutierrez; Ramesh Raskar (July 2013). "Femto-Photography: Capturing and Visualizing the Propagation of Light" (PDF). ACM Transactions on Graphics. 32 (4). doi:10.1145/2461912.2461928. hdl: 1721.1/82039 . S2CID   14478222 . Retrieved 21 November 2013.
  14. ↑ "NAC High Speed Cameras Are Popular Choices for European Broadcasting" . Retrieved 8 October 2010.
  15. ↑ Kesel, Antonia B. "Quantifying the Landing Reaction of Cockroaches" (PDF). University of Applied Sciences Bremen. Retrieved 15 December 2009.
  16. ↑ Ros, Ivo G.; Bassman, Lori C.; Badger, Marc A.; Pierson, Alyssa N.; Biewener, Andrew A. (2011-12-13). "Pigeons steer like helicopters and generate down- and upstroke lift during low speed turns". Proceedings of the National Academy of Sciences. 108 (50): 19990–19995. Bibcode:2011PNAS..10819990R. doi: 10.1073/pnas.1107519108 . ISSN   0027-8424. PMC   3250151 . PMID   22123982.
  17. ↑ Balch, Kris S. (16 September 1990). "Fourth-generation motion analyzer". 19th Intl Congress on High-Speed Photography and Photonics. Vol. 1358. pp. 373–398. doi:10.1117/12.23937. ISBN   9780819404190.{{cite book}}: |journal= ignored (help)
  18. ↑ Mason, Philip E.; Uhlig, Frank; Vaněk, Václav; Buttersack, Tillmann; Bauerecker, Sigurd; Jungwirth, Pavel (2015-03-01). "Coulomb explosion during the early stages of the reaction of alkali metals with water". Nature Chemistry. 7 (3): 250–254. Bibcode:2015NatCh...7..250M. doi:10.1038/nchem.2161. ISSN   1755-4330. PMID   25698335.
  19. ↑ "Education". ZT Research. 2017-05-06. Retrieved 8 September 2018.
  20. ↑ "High-Speed Imaging Services - Aimed Research".
  21. ↑ "Super Speed Camera Films Shock Wave" Popular Mechanics, October 1950, p. 158.
  22. ↑ weapon developmentChu, Dr. Peter C. "Non-Cylindrical Mine Drop Experiment" (PDF). Seventh International Symposium on Technology and Mine Problem, NPS, Monterey, California, USA. Retrieved 4 May 2006.. By using high speed digital cameras to record and playback the images in slow motion, the trajectory of a mine entering into the water can be optimized for accuracy by adjusting the shape of the mine and the entry angle into the water. There are many instances of high speed digital cameras used to study firearm ballistics "Handgun Wounding Effects Due to Bullet Rotational Velocity" (PDF). Archived from the original (PDF) on 22 December 2013. Retrieved 18 February 2013.
  23. ↑ Bridges, Andrew (1 August 2005). "INDUSTRY VIEW: Military test ranges make the switch from film to digital imaging". Military & Aerospace Electronics magazine. Retrieved 1 August 2005.
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