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Questions and Answers
What is the key motivation for pixel binning in CMOS image sensors?
What is the key motivation for pixel binning in CMOS image sensors?
CMOS sensors are less commonly used in consumer markets compared to CCD sensors.
CMOS sensors are less commonly used in consumer markets compared to CCD sensors.
False
What applications continue to use CCD sensors due to their low noise characteristics?
What applications continue to use CCD sensors due to their low noise characteristics?
High-end and scientific applications
CMOS image sensors are popular in mobile phones and _____ due to their low power consumption.
CMOS image sensors are popular in mobile phones and _____ due to their low power consumption.
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Match each type of image sensor with its primary characteristic:
Match each type of image sensor with its primary characteristic:
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What type of silicon is often used in photodiode chips?
What type of silicon is often used in photodiode chips?
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Photons with long wavelengths are more likely to be absorbed by silicon photodiodes.
Photons with long wavelengths are more likely to be absorbed by silicon photodiodes.
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What is the typical thickness range of the depletion layer in real photodiodes?
What is the typical thickness range of the depletion layer in real photodiodes?
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What is the unit of luminous intensity?
What is the unit of luminous intensity?
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Silicon photodiodes are used as basic building blocks for __________.
Silicon photodiodes are used as basic building blocks for __________.
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Irradiance is dependent on the wavelength of light.
Irradiance is dependent on the wavelength of light.
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What happens to the current-voltage (I-V) curve of a photodiode when it is exposed to light?
What happens to the current-voltage (I-V) curve of a photodiode when it is exposed to light?
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What is the relationship between luminous flux and luminous intensity?
What is the relationship between luminous flux and luminous intensity?
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Match the wavelength characteristics with their effects on photon absorption:
Match the wavelength characteristics with their effects on photon absorption:
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The bandwidth in electronics is typically expressed in ______.
The bandwidth in electronics is typically expressed in ______.
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If the photon energy is ___________, the photons are absorbed before they reach the depletion area of the photodiode.
If the photon energy is ___________, the photons are absorbed before they reach the depletion area of the photodiode.
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What does the term 'bandwidth' refer to in photonics?
What does the term 'bandwidth' refer to in photonics?
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Photodiodes can generate current without an external voltage when exposed to light.
Photodiodes can generate current without an external voltage when exposed to light.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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A _______ emits roughly one candela of luminous intensity.
A _______ emits roughly one candela of luminous intensity.
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Which of the following statements is true about electromagnetic radiation (EMR)?
Which of the following statements is true about electromagnetic radiation (EMR)?
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What occurs when the angle of incidence, $ heta_i$, is greater than the critical angle, $ heta_c$?
What occurs when the angle of incidence, $ heta_i$, is greater than the critical angle, $ heta_c$?
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In total internal reflection, the reflected wave has a different amplitude compared to the incident wave.
In total internal reflection, the reflected wave has a different amplitude compared to the incident wave.
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What is indicated by $ heta_c$ in the context of wave reflection?
What is indicated by $ heta_c$ in the context of wave reflection?
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When light travels from a denser medium to a less dense medium, the behavior of the wave depends on the angle of incidence with respect to the __________.
When light travels from a denser medium to a less dense medium, the behavior of the wave depends on the angle of incidence with respect to the __________.
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What is the result of incident light striking a surface at an angle less than the critical angle?
What is the result of incident light striking a surface at an angle less than the critical angle?
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Match the components of the electromagnetic wave to their behavior during reflection:
Match the components of the electromagnetic wave to their behavior during reflection:
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For the perpendicular component, the formula used to calculate the phase change is tan 𝜙 = __________.
For the perpendicular component, the formula used to calculate the phase change is tan 𝜙 = __________.
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Define total internal reflection.
Define total internal reflection.
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What defines the position and slope of a light ray in geometrical optics?
What defines the position and slope of a light ray in geometrical optics?
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Which of the following is a primary advantage of full-frame CCDs?
Which of the following is a primary advantage of full-frame CCDs?
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Ray matrices can only represent simple optical systems.
Ray matrices can only represent simple optical systems.
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Charge transfer in CCDs does not require any clock signals.
Charge transfer in CCDs does not require any clock signals.
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What is the purpose of the optic axis in ray optics?
What is the purpose of the optic axis in ray optics?
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In ray optics, the displacement and angle relationship is represented by a 2 x 2 ______.
In ray optics, the displacement and angle relationship is represented by a 2 x 2 ______.
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What does the water bucket analogy refer to in the context of CCD operation?
What does the water bucket analogy refer to in the context of CCD operation?
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In a full-frame CCD, each MOS pixel serves as the ______, charge storage element and a vertical CCD line element.
In a full-frame CCD, each MOS pixel serves as the ______, charge storage element and a vertical CCD line element.
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Match the following optical components with their effects:
Match the following optical components with their effects:
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Match the following CCD types with their characteristics:
Match the following CCD types with their characteristics:
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What is represented by the variables A, B, C, and D in a ray matrix?
What is represented by the variables A, B, C, and D in a ray matrix?
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Input displacement directly affects output angle in ray matrices.
Input displacement directly affects output angle in ray matrices.
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What are the two types of CCD lines used for charge transfer?
What are the two types of CCD lines used for charge transfer?
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The effect of an optical component on a ray is found by multiplying its ray ______.
The effect of an optical component on a ray is found by multiplying its ray ______.
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A minimum of three clock signals are required for charge movement in CCDs.
A minimum of three clock signals are required for charge movement in CCDs.
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What does the term 'fill factor' refer to in CCD sensors?
What does the term 'fill factor' refer to in CCD sensors?
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Study Notes
Introduction
- The material covers digital image processing and related topics.
Electromagnetic Radiation
- Electromagnetic radiation (EMR) is composed of self-propagating electromagnetic waves.
- It does not require a medium for propagation.
- It travels at the speed of light (300,000 km/s).
- EMR can be analyzed as waves or particles (photons).
Sound Waves
- Sound waves are mechanical waves.
- They require a medium (e.g., air, water) for propagation.
- They do not propagate in a vacuum.
- Sound waves cause pressure and displacement changes in a medium.
Sources of EM Radiation
- EMR is generated by stars, atomic nucleus decay, and human activities.
- The Sun is a significant source of EMR, emitting a wide range.
- Common household devices, medical equipment, and telecommunications emit EMR.
Two natures of Light (The Wave Nature of Electromagnetic Radiation)
- EMR can be treated as perpendicular, time-varying electric (E) and magnetic (B) fields.
- The simplest EMR wave is a sinusoidal wave.
- The mathematical description of EMR treated as a wave: Ex = Ecos(wt – kz - φo).
- Wavelength (λ), angular frequency (ω), and phase (φo).
- Phase velocity (v) = ω/k = λf
Phase Velocity
- Phase velocity (v) is the rate at which a point of constant phase (e.g., maximum amplitude) travels along the z-axis in the optical medium.
- In a medium with a refractive index n, phase velocity is given by v = c/n, where c is the speed of light in a vacuum.
Wave Packets
- Two waves with slightly different wavelengths, travelling in the same direction, generate a wave packet.
- Wave packets have an amplitude that is modulated at a frequency.
Group Velocity and Group Index
- Group velocity (vg) in a medium is defined as vg = ω/k.
- Group index (Ng) is defined as Ng = c/v = n – λ (dn/dλ)
- Both group velocity and group index are functions of wavelength.
Plane Waves
- A monochromatic plane wave is described by Ex = Ecos(wt – kz - φ0), where the quantity is constant in any plane perpendicular to the z-axis.
- The plane of constant E and t is called the wavefront.
The Divergence of EMR
- Far from the EMR source, EMR waves can be approximated as plane waves.
- Real-world EMR sources often show divergence, requiring careful consideration of the diverging beam.
- An EMR point source produces a spherical wavefront.
Reflection of Light
- EMR/light is treated according to wave theory when analyzing phenomena like interference and diffraction.
- Snell's law relates the propagation angles to refractive indices of two different media.
- There are incident and transmitted wave angles (θ₁, θ₂).
- n₁ and n₂ are the refractive indices of the first and second media, with n₁≠ n₂.
- sin(θ₁)/n₁ = sin(θ₂)/n₂
- Total internal reflection (TIR) occurs when n₁ > n₂ and the incident angle θ₁ is large enough.
Total Internal Reflection (TIR)
- TIR occurs when θ₁ > θc, where θc is the critical incidence angle.
- Critical incidence angle for TIR is defined by sin θc = n₂ / n₁
Reflection of Light (Continued)
- The reflected wave in TIR has the same amplitude as the initial wave but with a phase shift.
- The formulas for phase changes in reflection are dependent on whether the incident wave is perpendicular or parallel to the boundary.
Reflection Coefficients and Reflectance
- Fresnel equations define the reflection and transmission coefficients in terms of the electric field components.
- When normal incidence (θ₁ = 90°) occurs, the reflection coefficients are equal.
Photons
- EMR/light energy is carried by quanta called photons.
- The energy of a photon is dependent on its frequency (υ) or wavelength (λ), and is computed from E = hv = hc/λ, where h is Planck's constant and c is the speed of light.
Photon Interaction with Matter
- In particle treatment, photons interact with semiconductors such as silicon photodiodes, which can be used for imaging sensors.
The Spectrum
- EMR is categorized by wavelength into distinct regions including radio, microwave, infrared, visible, ultraviolet, X-rays, and gamma rays.
- This course focuses on the visible spectrum relevant to imaging.
Spectrum of Visible Light
- The visible spectrum ranges from approximately 400 nm to 700 nm.
- Different wavelengths are sensed by human eyes as different colors, with 400 nm being blue and 700 nm being red.
Electromagnetic Radiation and the Atmosphere
- Earth's atmosphere blocks some ranges of EMR.
- Visible light and most radio waves pass through the atmosphere in both directions.
Solar Radiation Spectrum
- The Sun's emission spectrum at sea level appears almost uniform in the visible range.
- A significant portion of solar radiation is in the infrared region.
- Absorption of light by atmospheric molecules (O₂, O₃, H₂O) causes dips in the spectrum.
Traditional Light Sources
- Incandescent lamps emit a lot of infrared radiation.
- Halogen lamps are more efficient but still emit much infrared radiation.
- Fluorescent lamps are the most efficient of the three.
Light Emitting Diodes (LEDs)
- LEDs have higher efficiency than traditional lamps.
- LEDs typically emit one color, and white light is generated with a phosphor coating.
Bandwidth
- Bandwidth is the width of the optical spectrum of the output of a light source (e.g., a LED).
- It is often expressed as FWHM (full-width at half-maximum).
Luminous Intensity, Luminous Flux, and Illuminance
- Luminous intensity (cd): the power emitted by a light source in a given direction in a unit solid angle, weighted by human eye sensitivity.
- Luminous flux (lm): the total power of light emitted by a source to all directions, weighted by human eye sensitivity.
- Illuminance (lx): luminous flux per unit area (e.g., lm/m²).
Radiant Intensity and Irradiance
- Radiant intensity: total power emitted by a light source in a given direction with respect to a unit solid angle and is independent of wavelength.
- Irradiance: The total power of light arriving on a surface and is independent of wavelength.
Summary (Additional)
- Discussion of how the concepts of this lecture apply to real-world digital imaging systems, with a particular focus on image sensors such as CCD and CMOS, and the related techniques and procedures to analyze the properties of the image captured and the objects.
Further Topics
- The material includes discussion of image processing techniques (e.g., filtering), measurement uncertainties, additional techniques, and considerations for dealing with non-ideal characteristics. Other topics include how to segment, analyze objects based on edges, and apply these techniques to real-world scenarios. Methods, such as histogram equalization and other non-linear methods, along with important considerations to obtain good measurements.
Additional Note
- The study notes are derived from the provided materials and should therefore provide considerable insight into the subject material presented.
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Description
This quiz covers the key concepts related to CMOS and CCD image sensors, exploring their characteristics, applications, and underlying physics. Topics include pixel binning motivations, the properties of photodiodes, and the effects of light on sensor performance. Test your knowledge on the advanced imaging technology used in various devices.
