High speed cameras can capture events at over 1,000 frames per second, allowing finer details to be seen when played back at normal speed. They focus light onto an image sensor, converting the image into an electronic format. The document discusses the high speed camera available in the author's lab and its uses, including combustion research, microfluidics, and sports broadcasts. It also covers aperture, depth of field, CCD and CMOS image sensors used in high speed cameras.

1. HIGH SPEED CAMERA
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2. High Speed Camera
• High speed cameras are a feature-specific type of video camera meant to capture events with
minute, fleeting details that could not be captured by cameras with a standard frame rate.
• They are capable of capturing sequences in excess of a 1,000 frames per second
• The video is played back at a slower frame rate, the details of the event are more apparent.
• They focus the light from the visible spectrum onto an image sensor which will turn the
image into an electronic and recordable medium.
• In our lab, MIRO LAB110 by PHANTOM is the high speed camera available.
• There are two lens one from NIKON and other from ZEISS.
• Also, we have a illuminator for bright light intensity.
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3. Uses of High Speed Camera
• Combustion applications: They are fast events that often have lighting issues as they quickly
fluctuate between being very dark and very bright. Phantom cameras have features that aid
researchers in dealing with these issues.
• Microfluidics: For studying spray behaviour for industrial applications.
• Particle Image Velocimetry (PIV): It is a method used to observe the flow of air, water, and
other invisible elements. Phantom cameras are equipped with high-resolution sensors to
make particle tracking simple.
• High-speed cameras are frequently used in television broadcasts of many major sporting
events for slow motion instant replays when normal slow motion is not slow enough.
• Digital Image Correlation: It is a non-contact method of observing how an object is affected
by impact and vibration. 3

4. Aperture of camera
• Aperture is the opening in a lens through which the light passes to enter the camera.
• Working of lens is similar to working of eyes.
• When we move between bright and dark environments, the iris in the eyes will either
expand or contracts controlling the size of the pupil.
• In photography, pupil of our eyes is called aperture.
• We can shrink and enlarge the size of aperture to allow more or less light to reach
camera sensor.
• Aperture does not only control the amount of light entering. But it also affects the
depth of field.
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5. • F number is used to express aperture.
• As F number increases aperture decreases.
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6. • Depth of field is the area of your image that is acceptably sharp (in focus).
• Large aperture – Large amount of foreground and back ground blur – Thin depth of field.
• Small aperture – Small amount of background blur which is typically ideal for some types of
photography such as landscape – Thick depth of field.
Aperture and Depth of field
F number Aperture Size Depth of Field
f/1.4 Very large Very thin
f/2.0 Large Thin
f/2.8 Large Thin
f/4.0 Moderate Moderately thin
f/5.6 Moderate Moderate
f/8.0 Moderate Moderately large
f/11.0 Small Large
f/16.0 Small Large
f/22.0 Very small Very large
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7. CCD (Charge Coupled Device)
• CCD is an integrated circuit etched into a silicon surface forming light sensitive elements
called pixels.
• It is based on the principle of photoelectric effect.
• If a photon with sufficient energy hits an electron in an outer shell of an atom, the transfer of
energy to the electron can be enough to free it from the atom.
• Today, high-speed cameras almost universally use CCD or CMOS image sensors.
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8. • CCD use a thin wafer of silicon to produce electrons from photons. Because silicon easily
reduces electrons with visible light.
• A tiny positive charged capacitor is attached to the silicon wafer in order to collect the freed
electrons.
• The photons starts producing electrons as soon as the shutter is opened and the capacitor
collects the freed electrons until the shutter is closed.
• Energy, 𝐸 =
ℎ𝑐
𝜆
where 𝜆 → 𝑃ℎ𝑜𝑡𝑜𝑛 𝑤𝑎𝑣𝑒𝑙𝑒𝑛𝑔𝑡ℎ.
𝑐 → 𝑆𝑝𝑒𝑒𝑑 𝑜𝑓 𝑙𝑖𝑔ℎ𝑡.
ℎ → 𝑃𝑙𝑎𝑛𝑘′𝑠 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡 = 6.626 × 10−34 𝑚2𝑘𝑔/𝑠
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10. • An additional circuit is required in CCD to convert analogue to digital signal to produce an
image.
• The analogue signal is produced on the chip and the digital signal is generated using camera
circuit board.
• Voltage across the capacitor represents the number of electrons the capacitor collected. This
information is sent to the computer.
• All the silicon sensor and the capacitor are miniaturized into an integrated circuit and it
represents pixel.
• CCD’s are made of thousands or even millions of pixels configured as an array.
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11. CMOS (Complimentary Metal Oxide Semiconductor)
• The working principle of CMOS is same as that of CCD.
• It also depends on the photoelectric effect to create electrical signals from light.
• The major difference from CCD is that, In CMOS each pixel has its own charge to voltage
conversion.
• Also, here the analogue to digital signal conversion also takes place inside the chip.
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