fresnel lenses in rear projection...
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Fresnel OpticsA Reflexite Company The Management of Light ®
Fresnel Lenses in Rear Fresnel Lenses in Rear Projection DisplaysProjection Displays
SID ProceedingsSID ProceedingsJune 2001June 2001
bybyArthur Davis, Robert C. Bush,Arthur Davis, Robert C. Bush,
John C. Harvey and Michael F. Foley, PhDJohn C. Harvey and Michael F. Foley, PhD
The Management of Light ®Fresnel A Reflexite Company
Fresnel OpticsA Reflexite Company The Management of Light ®
AbstractA plastic Fresnel lens positioned just before the diffusion screA plastic Fresnel lens positioned just before the diffusion screen en in a projection system can provide significantly superior cornerin a projection system can provide significantly superior cornerillumination, enhancing overall display luminance uniformity. illumination, enhancing overall display luminance uniformity. Fresnel lenses are also used within the light engine to collimaFresnel lenses are also used within the light engine to collimate te light through the LCD panel and focus light through the projectilight through the LCD panel and focus light through the projection on lens. Disadvantages include the added cost of the lenses, lens. Disadvantages include the added cost of the lenses, ghosting, printout of the Fresnel rings and moirghosting, printout of the Fresnel rings and moiréé patterns. patterns. Birefringence is important to control in polarizationBirefringence is important to control in polarization--sensitive sensitive applications.applications.
Without reduction of ghosting artifacts, Fresnel lenses will havWithout reduction of ghosting artifacts, Fresnel lenses will have e limited application in textlimited application in text--based RP systems. Ghosting is based RP systems. Ghosting is described in some detail including how it is caused, quantified described in some detail including how it is caused, quantified and reduced. Efforts to reduce cost and birefringence will also and reduced. Efforts to reduce cost and birefringence will also be be discussed.discussed.
Fresnel OpticsA Reflexite Company The Management of Light ®
Fresnel Lens Background•• Augustin Jean Augustin Jean
FresnelFresnel–– French PhysicistFrench Physicist–– 17881788--18271827–– Wave Theory of Wave Theory of
LightLight–– First use of First use of
Fresnels: Fresnels: Lighthouse Lighthouse LensesLenses
Fresnel OpticsA Reflexite Company The Management of Light ®
The Fresnel Lens
•• Periodic refractive Periodic refractive approximation to approximation to asphereasphere–– SlopesSlopes–– DraftsDrafts
Fresnel OpticsA Reflexite Company The Management of Light ®
Applications
•• Single Panel LCD Single Panel LCD ProjectorsProjectors
•• Overhead ProjectorsOverhead Projectors•• Rear Projection Rear Projection
DisplayDisplay–– Rear Projection Rear Projection
TelevisionsTelevisions–– Rear Projection Rear Projection
MonitorsMonitors
Fresnel OpticsA Reflexite Company The Management of Light ®
Single Panel LCD Projector
•• Fresnel Lenses can increase the Fresnel Lenses can increase the collected light in single panel LCD collected light in single panel LCD displaysdisplays
Fresnel OpticsA Reflexite Company The Management of Light ®
Overhead Projectors
Transmissive Reflective
Fresnel OpticsA Reflexite Company The Management of Light ®
Rear Projection Display
•• Collimation Collimation increases overall increases overall display luminancedisplay luminance
Luminance enhancement using Fresnel Lens
Fresnel OpticsA Reflexite Company The Management of Light ®
Fresnel Lens ImagingCorrect Orientation Incorrect Orientation
•• Minimize draft Minimize draft lossloss–– Judicious draft Judicious draft
designdesign–– Proper lens Proper lens
orientationorientation
Fresnel OpticsA Reflexite Company The Management of Light ®
Ghosting
•• Caused by Caused by internal internal reflectionsreflections
•• 3.9% 3.9% -- 10%10%•• Limits high Limits high
contrast contrast applicationsapplications
•• Multiple GhostsMultiple Ghosts
Fresnel OpticsA Reflexite Company The Management of Light ®
Ghost Suppression
•• Lens tintingLens tinting•• Draft blackeningDraft blackening•• Broadband antiBroadband anti--reflection coatingreflection coating•• Proprietary processes and designsProprietary processes and designs
–– Negligible ghostingNegligible ghosting–– Low f/#Low f/#–– High resolutionHigh resolution–– Successfully implemented in RPM Successfully implemented in RPM
applicationsapplications
Fresnel OpticsA Reflexite Company The Management of Light ®
Moiré•• Fresnel rings can Fresnel rings can
cause a moircause a moiréépatternpattern with the with the lines of a lenticular lines of a lenticular diffuserdiffuser
•• With proper With proper engineering of the engineering of the pitch, moirpitch, moiréé can be can be reduced to reduced to acceptable contrast acceptable contrast levelslevels
Fresnel OpticsA Reflexite Company The Management of Light ®
Metrology
Fresnel OpticsA Reflexite Company The Management of Light ®
ManufacturingReplication Processes
Cross section of injection molded Fresnel Cross section of compression molded Fresnel
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