Equations

Common DOE surfaces

Sinusoidal, triangle

Max D.E. ~ 30% +/-1 order Power distribution follows Bessel function in the scaler region. T File:Simeq.gif File:Lambda.gif for transmission. T File:Simeq.gif File:Lambda.gif / 4 for reflection. Easily replicated or deep etch can yield higher efficiency.

Square, rectangle

Max D.E. ~ 40% +/-1 order. Power distributions favors odd orders. Pi phase shift typical. Classic binary grating. T File:Simeq.gif File:Lambda.gif for transmission. T File:Simeq.gif File:Lambda.gif / 4 for reflection.

Blazed, sawtooth

Max D.E ~ 98% Reflection Case: File:Lambda.gif = 2 d sin a T = File:Lambda.gif / 2 +/- 10% Transmission Case: File:Lambda.gif = d sin b a File:Simeq.gif 2b T = File:Lambda.gif / (n-1) +/- 10% Surface shadows reduce D.E. by File:Equ1.gif Wavelength changes reduce D.E. by File:Equ2.gif

Holographic Deflectors (hologons)

N = File:Theta.gif D / ( 1.4 File:Lambda.gif) N = number of resolvable spots File:Theta.gif = full scan angle in radians D = beam diameter in microns File:Lambda.gif = wavelength File:Phi.gif = wedge angle of glass Special case of linear scan and near wobble invariance File:Invariance1.gif max straight scan angle ~ 36 deg Dynamic wobble File:Dynwob1.gif Wedge wobble = (n-1) File:Phi.gif Scan angle multiplier = 1.4 @ 90degrees cross scan angle

Last modified on 9/29/97