SO101-SENSOR THEORY

Question 1

What is the EO spectrum?

Answer 1

It is the entire range of all possible frequencies/wavelengths of electromagnetic radiation.

Question 2

What is the visual spectrum?

Answer 2

The electromagnetic waves that can be detected by the human eye.

Question 3

How efficient is the human eye as it pertains to visible light?

Answer 3

Not very efficient, it has an efficiency of 1-5%

Question 4

What spectrum do all EO sensors operate in?

Answer 4

The visible light spectrum.

Question 5

What is within the infrared spectrum?

Answer 5

The gap between red light and microwaves. Its vey large.

Question 6

What are the 5 sub-ranges of IR radiation?

Answer 6

Ner Infrared
Short wavelength Infrared
Mid wavelength Infrared
Long wavelength Infrared
Far Infrared

Question 7

How is Near Infrared(NIR) defined?

Answer 7

Its Water absorption properties and it is common use in fiver optic communication because of low attenuation losses in SiO2 glass (silica) fiber.

Question 8

What is a common use for for NIR?

Answer 8

Dramatic effects in photography, NVGs, IR pointers, IR strobes, etc.

Question 9

What is NIR’s range?

Answer 9

0.74-1.4

Question 10

What operates in short wavelength IR(SWIR)?

Answer 10

Military laser designators operate in SWIR.

Question 11

What is Mid Wavelength IR(MWIR) also known as?

Answer 11

Intermediate IR.

Question 12

What operates in MWIR?

Answer 12

The MX series IR used on the AC-130

Question 13

What temperatures can the MWIR sensors detect?

Answer 13

It can detect temperatures somewhat above body temperatures.

Question 14

What is Long wavelength IR(LWIR)?

Answer 14

LWIR is similar to to microwave radiation and is a form of radiation emitted from within any material of any temperature above absolute 0.

Question 15

Is LWIR a superior targeting system to MWIR?

Answer 15

Yes it is.

Question 16

Can LWIR see through smoke? Can MWIR?

Answer 16

LWIR yes, MWIR no.

Question 17

Whats more expensive MWIR or LWIR?

Answer 17

LWIR is more expensive.

Question 18

Examples of LWIR?

Answer 18

AC-130U’s AN/AAQ-26, LANTRIN 2000, and others.

Question 19

What is Far Infrared(FIR) used for?

Answer 19

It is used to detect explosive and chemical agents by infrared spectroscopy.

Question 20

Why do we need EO sensors?

Answer 20

Because they are 350 times more efficient than the human eye.

Question 21

How is electo optics defined?

Answer 21

The technology associated with those components,devices, and systems which are designed to interact between the electromagnetic(optical) and the electric(electronic) state.

Question 22

What is the key to visual imaging?

Answer 22

Detecting the differences in reflectance between the target and background objects.

Question 23

What utilizes CMOS technology?

Answer 23

The MX20EOW and EON sensors on the AC-130.

Question 24

When do EO sensors operate best?

Answer 24

In the daytime or bight night because they rely on existing light conditions.

Question 25

Can weather effect albedo(reflectance)?

Answer 25

Yes

Question 26

Are EO lenses made from glass?

Answer 26

No because glass is a poor transmitter in The infrared wavelengths.

Question 27

What is the heart of all imagers?

Answer 27

The detector.

Question 28

What is the general rule regarding white hot and black hot imagaing?

Answer 28

Use white hot to search and look for target detail in blackhot.

Question 29

Can IR sensor detect indirect or direct radiation or both?

Answer 29

It can detect both.

Question 30

What do hotter areas look like on the sensor?

Answer 30

The hotter areas emit more radiation and look lighter in color.

Question 31

How do Ocean areas tend to gain and lose heat?

Answer 31

Very slowly

Question 32

What is the relationship between clutter and the correct target?

Answer 32

The higher the clutter the harder it is to see the target and vice-versa.

Question 33

What are the three factors that effect the total power emanating from a contact?

Answer 33

Temperature, Emissivity and Area.

Question 34

What does sensor contrast rely on?

Answer 34

It relies on the difference in reflectivity between the target and the background.

Question 35

What is extinction?

Answer 35

The loss of EM energy as it leaves a target/background.

Question 36

What is absorption?

Answer 36

Absorption is the process by which EM energy is absorbed by atmospheric particles.

Question 37

What is scattering?

Answer 37

Scattering is the redirection of photons by molecules, aerosols, or other particles in the air.

Question 38

What are the two types of scattering and how do you define them?

Answer 38

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.

Question 39

What is scintillation?

Answer 39

It is the effect that causes stars to twinkle and happens when Ir radiation passes through a temperature variation.

Question 40

What is thermal crossover?

Answer 40

It is the point when the target and its background have reached the same temperature.

Question 41

How do you define sunrise?

Answer 41

The crossing of the visible horizon by the upper limb if the rising sun.

Question 42

How do you define sunset?

Answer 42

The crossing of the visible horizon by upper limb of the setting sun.