Exam 1 - EO/LASERs

Which law calculates wavelength of maximum radiation?

Wien’s Law

Which law dictates the shape of the spectral radiant emittance vs. wavelength curve as a function of temperature and wavelength?

Planck’s Law

Which law gives us the area under the curve, or exitance?

Stefan-Boltzmann’s Law

Which law gives us the transmittance as a function of wavelength, environmental attenuation factors, and range to target?

Beer-Lambert Law

Characteristics of LASERs

• coherent

• inefficient

• low divergence (collimated)

• monochromatic

Military applications for LASERs

• dazzling

• directed energy weapons

• designating targets

• range approximation

When an EM wave strikes a conductive surface and bounces off it at an angle equal to the incident angle

reflection

The tendency of EM waves to spread out, or bend around objects

Diffraction

When an EM wave passes into a medium with a different speed of propagation, and the EM wave bends towards/into the medium of slower wave propagation.

Refraction

What is thermal crossover

When the environmental heating cycle causes target temperature = environment temperature (no contrast)

What variable accounts for the detector’s sensitivity to specific wavelengths of emitted energy?

Bandwidth factor

T/F: Different gray bodies with the same temperature will always have the same exitance

False

T/F: In comparison to the radio spectrum, the electro-optic spectrum consists of higher frequencies and shorter wavelengths.

True

What unit of measure is most commonly used to describe the EO spectrum?

microns

_____ converts ideal exitance into actual material exitance by accounting for differences in blackbody vs. graybody properties.

Emissivity

The Beer-Lambert Law accounts for which types of attenuation?

scattering, absorption

A difference in starting point between two EM waves is a difference in

phase angle

T/F: LASER beam spreading occurs in the same manner as non-collimated white light from a point source

False