AVIT 126 Exam II Questions with
All Correct Answers 2024 Update
How does weather affect IR imagery? - Answer--humidity is the most important external
factor affecting the quality of an IR image
-recent rain or snow tends to equalize surface temperatures causing washed-out
conditions that are similar to thermal crossover
-in dust and haze, IR imaging devices have better capability looking through dust and
haze than most EO systems
What is a Sun Angle? - Answer-shadows can cause a localized crossover prior to the
rest of the landscape
How does Solar Heating affect IR imagery? - Answer--color and composition of an area
affect the amount of energy absorbed --> a black surface will absorb more and radiate
more IR energy than a white surface
-temperature contrast is the key to IR imaging
What does it mean when something is "internally heated" and what are some examples
for IR imagery? - Answer--internally heated bodies or self-emitters create and dissipate
their own heat
-examples: running engines, active exhausts, working boilers, operating transformers,
heated and cooled buildings, people
What are Fused Images? - Answer--combines IR images with Day TV or Low Light TV
(LLTV)
-electronically takes the best aspects of the two and brings them together into a single
image
-can be used to bring out some details not seen well in either Visual or IR images
What are lasers concerning IR images? - Answer--illumination, wide laser.
-Laser Target Marker (LTM) can be seen through NVG
-night vision google (NVG) capable laser
What does EO stand for? - Answer-Electro Opcal
Which spectrum is EO imaging? - Answer-Visible light spectrum , .4 to .7 um (or 400 to
700 nm)
, What is the difference between uncontrolled light and controlling light by pinhole? -
Answer-Uncontrolled light rays: refracted from two points (pipe and coat) travel in all
directions striking the film over its surface, they never form an image of the pipe or coat
anywhere on the film
Pinhole: a simple "box" camera with a pinhole lets only a few rays of light from each
point through to strike the film in light clusters, because little light is let in the exposure,
time is long - measured in minutes- but a fairly good picture results
What are the 5 camera basics? - Answer--body
-lens
-aperture
-shutter
-image sensor
Lens - Answer-take the many rays of reflected light bouncing on a single point and
redirects them so they come together at a corresponding single point on the film (or
other collector)
Differences in Lens - Answer--there is no major difference in principle between a lens
used for a small camera, a video camera, a telescope, a microscope, or other apparatus
but the detailed design and construction are different
-a lens may be permanently fixed to a camera, or it may be interchangeable with lenses
of different focal lengths, apertures, and other properties
What are the 5 general bands that infrared can be broken up into? - Answer-- Near
Infrared (NIR) --> .75 to 1.4 um
- Short-Wavelength Infrared (SWIR) --> 1.4 to 3 um
- Mid-Wavelength Infrared (MWIR) --> 3 to 8 um
-Long-Wavelength Infrared (LWIR) --> 8 to 15 um
-Far-Infrared (FIR) --> 15 to 1000 um
Of the 5 bands of IR, which are reflective properties and which are heat-emitted
properties? - Answer--Reflective: NIR and SWIR (Cold colors on the spectrum)
-Heat Emitted: MWIR, LWIR, and FIR (warm colors on the spectrum)
--> split between SWIR and MWIR
Describe the founding of IR - Answer--founded by Sir Frederick William Hershel in 1800
who was a musician and astronomer
-used colored filters for telescope observation of the sun
-investigated temperature of colors of the spectrum
What is the meaning of Infrared in Latin? - Answer-"Below the red"
-infra = below
What are the trends of IR? - Answer--temperature increase from violet to red
All Correct Answers 2024 Update
How does weather affect IR imagery? - Answer--humidity is the most important external
factor affecting the quality of an IR image
-recent rain or snow tends to equalize surface temperatures causing washed-out
conditions that are similar to thermal crossover
-in dust and haze, IR imaging devices have better capability looking through dust and
haze than most EO systems
What is a Sun Angle? - Answer-shadows can cause a localized crossover prior to the
rest of the landscape
How does Solar Heating affect IR imagery? - Answer--color and composition of an area
affect the amount of energy absorbed --> a black surface will absorb more and radiate
more IR energy than a white surface
-temperature contrast is the key to IR imaging
What does it mean when something is "internally heated" and what are some examples
for IR imagery? - Answer--internally heated bodies or self-emitters create and dissipate
their own heat
-examples: running engines, active exhausts, working boilers, operating transformers,
heated and cooled buildings, people
What are Fused Images? - Answer--combines IR images with Day TV or Low Light TV
(LLTV)
-electronically takes the best aspects of the two and brings them together into a single
image
-can be used to bring out some details not seen well in either Visual or IR images
What are lasers concerning IR images? - Answer--illumination, wide laser.
-Laser Target Marker (LTM) can be seen through NVG
-night vision google (NVG) capable laser
What does EO stand for? - Answer-Electro Opcal
Which spectrum is EO imaging? - Answer-Visible light spectrum , .4 to .7 um (or 400 to
700 nm)
, What is the difference between uncontrolled light and controlling light by pinhole? -
Answer-Uncontrolled light rays: refracted from two points (pipe and coat) travel in all
directions striking the film over its surface, they never form an image of the pipe or coat
anywhere on the film
Pinhole: a simple "box" camera with a pinhole lets only a few rays of light from each
point through to strike the film in light clusters, because little light is let in the exposure,
time is long - measured in minutes- but a fairly good picture results
What are the 5 camera basics? - Answer--body
-lens
-aperture
-shutter
-image sensor
Lens - Answer-take the many rays of reflected light bouncing on a single point and
redirects them so they come together at a corresponding single point on the film (or
other collector)
Differences in Lens - Answer--there is no major difference in principle between a lens
used for a small camera, a video camera, a telescope, a microscope, or other apparatus
but the detailed design and construction are different
-a lens may be permanently fixed to a camera, or it may be interchangeable with lenses
of different focal lengths, apertures, and other properties
What are the 5 general bands that infrared can be broken up into? - Answer-- Near
Infrared (NIR) --> .75 to 1.4 um
- Short-Wavelength Infrared (SWIR) --> 1.4 to 3 um
- Mid-Wavelength Infrared (MWIR) --> 3 to 8 um
-Long-Wavelength Infrared (LWIR) --> 8 to 15 um
-Far-Infrared (FIR) --> 15 to 1000 um
Of the 5 bands of IR, which are reflective properties and which are heat-emitted
properties? - Answer--Reflective: NIR and SWIR (Cold colors on the spectrum)
-Heat Emitted: MWIR, LWIR, and FIR (warm colors on the spectrum)
--> split between SWIR and MWIR
Describe the founding of IR - Answer--founded by Sir Frederick William Hershel in 1800
who was a musician and astronomer
-used colored filters for telescope observation of the sun
-investigated temperature of colors of the spectrum
What is the meaning of Infrared in Latin? - Answer-"Below the red"
-infra = below
What are the trends of IR? - Answer--temperature increase from violet to red
