Transcript Slide 1
Using Your Classroom Projector to Demonstrate Properties of Light 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 • 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 Low Pass Three Color Image System Red Image Object High Pass Green Image 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) Digital Light Processing (DLP) Texas Instruments DLP Chip: 921,600 mirrors (1280x720 pixels) Liquid Crystal Display (LCD) Dichroic Combiner cube LCD Chip Blue Dichroic Mirror Red Dichroic Mirror Light Source LCD Projector Dichroic Combiner Cube Liquid Crystal over Silicon An LCoS Projector 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 many companies 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. White Red Green Blue Yellow = Red + Green Magenta = Red + Blue Cyan = Green + Blue White = Red + Blue + Green Polarization 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