Measures of Source Intensity

1. Radiant Flux, Φ

Rate of transfer of energy

Φ = δQ/δt (W)

Measures of Source Intensity

2. Radiant Intensity, I

Radiant flux per unit solid angle from a point source

I = δΦ/δΩ (W/sr)

Measures of Source Intensity

3. Radiance, B

Radiant flux per unit solid angle per unit projected area

B = δ2Φ/(δΩ δA) (W sr-1 cm-1)

Measures of Source Intensity

4. Irradiance, E

Radiant flux per unit projected area

E = δΦ/δA (W cm-1)

Measures of Source Intensity

5. Spectral Radiance, Bλ

Radiance per unit wavelength interval

Bλ = B/δλ (W sr-1 cm-1 nm-1)

Optical Components of Imaging Systems

1. Windows

2. Lenses

3. Mirrors

4. Turning Prisms

5. Beam Splitters

6. Fiber Optics

Transmittance of Window Materials

Transmittance of Window Materials

Reflectance of Mirror Materials

Interaction of Light with an Interface

Interaction of Light with an Interface

Law of Specular Reflection

Θ1 = Θ3

Snell’s Law of Refraction

n1sin Θ1 = n2sin Θ2

Reflection Losses at an Interface(unpolarized light)

Reflection Losses at an Interface

a = unpolarizedb = perpendicularly polarizedc = parallel polarized

(Note Brewster’s Angle)

Reflection at an Interface(Total Internal Reflection)

Propagating from high to low n

Total Internal Reflection

n1sin Θ1 = n2sin Θ2

n1 > n2

Θ2 = 90

sin Θ1 = n2/ n1

Lens Maker’s Formula

R2 < 0

1/f = (n-1) (1/R1 – 1/R2)

For a Biconvex Lens, R1 = -R2

Lens Formula

1/S1 + 1/S2 = 1/f

S1 = object distanceS2 = image distance

f = focal length

1/S1 + 1/S2 = 1/f

Relative Aperture of an Optical Component

D/S1

where:

D = limiting diameter

S1 = distance from source

F-number (F/n)

F/n = S1/D

The solid angle of light collected byan optical component is given by:

Ω = (π/4) (F/n)-2

Ω = (π/4) (F/n)-2

Beam Splitters

Optical Fibers

Optical Fibers

Turning Prisms

Sample Cells