OBT Principles of Optical Beam Physics 2

Question 1

Which property of light determines its energy per photon in optical beam therapy?

Accepted Answer

Wavelength

Answer

Photon energy is inversely proportional to wavelength (E = hc/λ), so shorter wavelengths carry higher energy per photon.

Question 2

What term describes the phenomenon where optical beam intensity decreases as it travels through tissue?

Accepted Answer

Attenuation

Answer

Attenuation refers to the reduction in beam intensity due to absorption and scattering as light propagates through tissue.

Question 3

In a Gaussian beam profile, where is the intensity at its maximum?

Accepted Answer

At the beam center (on-axis)

Answer

A Gaussian beam has its peak intensity at the center axis, with intensity decreasing exponentially toward the edges.

Question 4

What is the Rayleigh range of a focused optical beam?

Accepted Answer

The distance from the waist where beam area doubles

Answer

The Rayleigh range is the axial distance from the beam waist at which the beam cross-sectional area doubles, marking the boundary of the focal zone.

Question 5

Which interaction mechanism primarily accounts for therapeutic heating when near-infrared light is absorbed by water in tissue?

Accepted Answer

Photothermal conversion

Answer

Photothermal conversion occurs when absorbed photons are converted to heat via molecular vibration, producing therapeutic warming effects in tissue.

(OBT) Optical Beam Therapy Certification Practice Test