Sinusoidal, triangle

• Max D.E. ~ 30% +/-1 order

• Power distribution follows Bessel function in the scaler region.

• T for transmission.

• T / 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 for transmission.

• T / 4 for reflection.

Blazed, sawtooth

• Max D.E ~ 98%

• Reflection Case:
  • = 2 d sin a

  • T = /2 +/- 10%

• Transmission Case:
  • = d sin b

  • a 2b

  • T = / (n-1) +/- 10%

  • Surface shadows reduce D.E. by

  • Wavelength changes reduce D.E. by

• N = D / ( 1.4 )

• N = number of resolvable spots

• = full scan angle in radians

• D = beam diameter in microns

• = wavelength
  

• = wedge angle of glass

• Special case of linear scan and near wobble invariance max straight scan angle ~ 36 deg

• Dynamic wobble

• Wedge wobble = (n-1)

• Scan angle multiplier = 1.4 @ 90degrees cross scan angle