Introduction to DLP Optics DLP Optics Scott Dewald Ways to use - - PowerPoint PPT Presentation

Introduction to DLP Optics DLP Optics

Scott Dewald

• Object plane – project an image of the DMD

surface onto another surface (or a virtual image, e.g. HUD)

• Place at a system stop or Fourier plane–

spatial filtering or light modulation (including

Ways to use the DMD

spatial filtering or light modulation (including holographic data storage)

• Place in a diffracted beam – wavelength

selection/spectroscopy

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How the Light Is Steered

Projection

24º 48º

Light Dump

“ “ “ “Flat” State

• +/- 12º tilt angle
• n mirrors permits

4 nonoverlapping cones of light at f/2.4

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0º

Projection Lens Light Source

• 24º

“ “ “ “On” State (+12º) “ “ “ “Off” State (-12º)

On State Energy

D F

F/# = F/D = 2.4 for 11.5 º beam

f/2.4

What Does Telecentric Mean?

Pupil at Infinity Pupil

• Telecentric: Projection and/or

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• Telecentric: Projection and/or

Illumination pupils at infinity

• Each pixel “sees” rays from the

same f/# and direction

• Better uniformity in on and off

states

• Can be more compact
• Larger projection lens
• Requires TIR prism
• Non-Telecentric: Projection pupil

near entrance of projection lens

• Generally requires offset

illumination

TIR Prism

• TIR Prism discriminates between

incoming and outgoing rays based on angle

• All rays less than critical angle

(approx. 41.2 degrees in BK7) will

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(approx. 41.2 degrees in BK7) will pass; rest will reflect

• Air gap is made small (approx. 10

um) to reduce astigmatism in projected image

Lamp and Integrator

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Illumination Relay Optics

Integrator

Projection Lens TIR

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Aperture Stop

Integrator

DMD TIR Prism To obtain maximum uniformity of illumination at the DMD, the relay

• ptics should be telecentric in both object and image space, with

no vignetting.