SO101-SENSOR THEORY Flashcards
What is the EO spectrum?
It is the entire range of all possible frequencies/wavelengths of electromagnetic radiation.
What is the visual spectrum?
The electromagnetic waves that can be detected by the human eye.
How efficient is the human eye as it pertains to visible light?
Not very efficient, it has an efficiency of 1-5%
What spectrum do all EO sensors operate in?
The visible light spectrum.
What is within the infrared spectrum?
The gap between red light and microwaves. Its vey large.
What are the 5 sub-ranges of IR radiation?
Ner Infrared Short wavelength Infrared Mid wavelength Infrared Long wavelength Infrared Far Infrared
How is Near Infrared(NIR) defined?
Its Water absorption properties and it is common use in fiver optic communication because of low attenuation losses in SiO2 glass (silica) fiber.
What is a common use for for NIR?
Dramatic effects in photography, NVGs, IR pointers, IR strobes, etc.
What is NIR’s range?
0.74-1.4
What operates in short wavelength IR(SWIR)?
Military laser designators operate in SWIR.
What is Mid Wavelength IR(MWIR) also known as?
Intermediate IR.
What operates in MWIR?
The MX series IR used on the AC-130
What temperatures can the MWIR sensors detect?
It can detect temperatures somewhat above body temperatures.
What is Long wavelength IR(LWIR)?
LWIR is similar to to microwave radiation and is a form of radiation emitted from within any material of any temperature above absolute 0.
Is LWIR a superior targeting system to MWIR?
Yes it is.
Can LWIR see through smoke? Can MWIR?
LWIR yes, MWIR no.
Whats more expensive MWIR or LWIR?
LWIR is more expensive.
Examples of LWIR?
AC-130U’s AN/AAQ-26, LANTRIN 2000, and others.
What is Far Infrared(FIR) used for?
It is used to detect explosive and chemical agents by infrared spectroscopy.
Why do we need EO sensors?
Because they are 350 times more efficient than the human eye.
How is electo optics defined?
The technology associated with those components,devices, and systems which are designed to interact between the electromagnetic(optical) and the electric(electronic) state.
What is the key to visual imaging?
Detecting the differences in reflectance between the target and background objects.
What utilizes CMOS technology?
The MX20EOW and EON sensors on the AC-130.
When do EO sensors operate best?
In the daytime or bight night because they rely on existing light conditions.
Can weather effect albedo(reflectance)?
Yes
Are EO lenses made from glass?
No because glass is a poor transmitter in The infrared wavelengths.
What is the heart of all imagers?
The detector.
What is the general rule regarding white hot and black hot imagaing?
Use white hot to search and look for target detail in blackhot.
Can IR sensor detect indirect or direct radiation or both?
It can detect both.
What do hotter areas look like on the sensor?
The hotter areas emit more radiation and look lighter in color.
How do Ocean areas tend to gain and lose heat?
Very slowly
What is the relationship between clutter and the correct target?
The higher the clutter the harder it is to see the target and vice-versa.
What are the three factors that effect the total power emanating from a contact?
Temperature, Emissivity and Area.
What does sensor contrast rely on?
It relies on the difference in reflectivity between the target and the background.
What is extinction?
The loss of EM energy as it leaves a target/background.
What is absorption?
Absorption is the process by which EM energy is absorbed by atmospheric particles.
What is scattering?
Scattering is the redirection of photons by molecules, aerosols, or other particles in the air.
What are the two types of scattering and how do you define them?
Molecular scattering, which is when light is scattered by particles much smaller than the wavelength of the incident radiation.
Aerosol scattering; which is when large particles such as dust or smog scatters the light or thermal energy by reflection.
What is scintillation?
It is the effect that causes stars to twinkle and happens when Ir radiation passes through a temperature variation.
What is thermal crossover?
It is the point when the target and its background have reached the same temperature.
How do you define sunrise?
The crossing of the visible horizon by the upper limb if the rising sun.
How do you define sunset?
The crossing of the visible horizon by upper limb of the setting sun.
