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Usin g Yo ur Cla ssroo m Pro jector to Dem onstra te Pr operti es of Li ght. Dr. Michael Ottinger and Dr. Brian Bucklein Missouri Western State University St Joseph, MO 64507 American Association of Physics Teachers 2012 Winter Meeting – Ontario, California February 6, 2012. Outline.
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Using YourClassroomProjectortoDemonstrateProperties of Light Dr. Michael Ottinger and Dr. Brian BuckleinMissouri Western State UniversitySt Joseph, MO 64507 American Association of Physics Teachers 2012 Winter Meeting – Ontario, CaliforniaFebruary 6, 2012
Outline • How are RGB images created? • How do DLP, LCD and LCoS Projectors work? • What are Spectral Glasses? • Simple Demonstration of the Separation and Mixing of Colors using and LCD Projector • Demonstration of the Polarization of Light
Three Color Image System Low Pass Red Image Green Image High Pass Object RGB Filters Blue Image
Three Color Image System Red Lamp Red Image Superimpose Images Blue Lamp Blue Image Green Lamp Green Image
Methods for Reproducing RBG(Common Types of Projectors) • Digital Light Processing (DLP) • Liquid Crystal Display (LCD) • Liquid Crystal on Silicon (LCoS)
Digital Light Processing (DLP) Texas Instruments DLP Chip: 921,600 mirrors (1280x720 pixels)
LCD Projector Dichroic Combiner cube LCD Chip Blue Dichroic Mirror Red Dichroic Mirror Light Source
LCoS Projector UHP Mercury Lamp Note: Green is Polarized Perpendicular to Red and Blue
Using the Projector to Teach Colors • Diffraction Grating Glasses • Available through manycompanies for about $0.25 to $0.45 each • 500 lines/mm, linear diffraction grating
Breaking down the Colors • The following slides were made by using the “Shapes” drop down in PowerPoint to make two thin rectangular lines. • The top line was set to white and, using the color setting the bottom line was set to different color combinations.
Please put on your spectral glasses
You may remove your spectral glasses
Polarization • LCD and LCoS Projectors use Polarized Light • Typically the Red and Blue have the same polarization • Green is polarized perpendicularly to the Red and Green
Conclusions • Classroom projectors create images from three color regions of polarized light (RGB) • Using the projector and inexpensive spectral glasses you can demonstrate color mixing. • Polarization of light can be demonstrated from the different polarizations of the light
Pictures were taken by placing the spectral glasses on the front of a digital camera Pictures of Spectral Lines
Polarization of Projector Light