High Speed Video

Mr. Dehnert

Nov 4^th 2015

Couriertronics  (Electrical Engineer)

High Speed Video

Social Values:

-          The use of high tech slow motion cameras can apply to many fields of study. Slowing down high speed actions and reactions can help scientists and engineers observe, analyze, and gather data from things like explosions to car crashes. Being able to understand things like car crashes and what happens during such a collision enables engineers to innovate and implement safer vehicle technology to protect everyday lives. Here (just for fun) is a link to a system that can visualize near the speed of light! http://news.mit.edu/2011/trillion-fps-camera-1213

Government and Economics:

-          The use of nanotechnology is heavily linked to the camera industry and slow motion capturing technology. Silicon is one of the main elements used for camera technology to manufacture circuits and image detectors that enables cameras to function. Silicon is also used because it is a very abundant element. The use of this nanotechnology contributes to how expensive some cameras are. Being able to manufacture and produce this technology at large quantities and implementing them into cameras helps find a balance in pricing. That is where economies of scale comes into play.

Terms:

-          Image Detector – made of silicon (1000 x 1000 pixels in slow-mo detector)

-          Pixel – Stands for picture element
-      Voxel - 

-          Blur – Motion across a pixel causes blur

-          Hysteresis – phenomenon of our eyes that remembers a past image while another one is being seen, causing images to look continuous

-          Frame rate – the frequency at which a picture sequence is displayed

o   Frame rate of the human eye – 24-30 frames/second

-          Human blink -  200 milliseconds

-          Photoelectric  effect – electrons that are emitted when light shines upon them (discovered by Albert Einstein)

Concepts:

-          Different materials sensitive to different wavelengths

-          Silicon is sensitive to the same wavelengths our eyes see

-          Difference in charges (of e^-) across a pixel field is relayed by a circuit which is then displayed as an image

-          To get a color image, filters are put over pixels so only desired wavelengths can penetrate

-          Different materials are sensitive to different wavelengths

-          Depth of view gets narrower when capturing high speed images

-          $30,000-$120,000 for high speed capturing cameras

Connections:

SME – high speed cameras can be used to diagnose manufacturing problems

PV cells – also use silicon because Si inherently interacts with light from a very similar wavelength distribution to that of the sun’s light

And a little summary from last year’s student:  Normal cameras capture images at 30 to 60 frames per second (fps).  This is close to the rate at which humans perceive images, making these frame rates appropriate for recording at normal speeds.  Frames are captured when pixels behind the lens of the camera are exposed to light.  These pixels are extremely small, and sensitive to visible light.  Silicon is a good material for this purpose because it absorbs light at visible wavelengths (400 to 700 nanometers).   Photons reflected off of the objects or people being recorded hit the pixels, and the absorbed light is recorded for each pixel.  The image quality depends on the number of pixels and the amount of light that hits the pixels.  High speed cameras, with frame rates of up to millions of fps, are specially designed to move this high quantity of information very quickly.  One way they record so quickly is by moving the information from the pixels that are exposed to layers of pixels underneath that store the information until it can be transferred to a computer.  Recording at high speeds requires more light, so sources of light are often set up to ensure good exposure on the pixels. Mr. Dehnert gave us an analogy of rain and buckets with lids. To take many frames per second, the “lid on each bucket” (pixel) is opened for such a short amount of time that very few “raindrops” (photons) have time to get in, so we need a lot of light.