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6C20.40 - Fresnel Zone Plate Lens

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6C20.40 - Fresnel Zone Plate Lens

Title6C20.40 - Fresnel Zone Plate Lens

​To demonstrate how to focus light using diffraction instead of refraction or reflection with visible light.

Assembly Instructions

​A laser with beam expander (Camera Lens Computar) is aligned with a rather tight collamated beam.  The expanded beam is then passed through the Fresnel Zone Plate.  Using an image plate and camera, move them along the axis to locate the image position.

Setup Time10
Operation Time7
Preview Time10
Operation Instructions

Turn off the room lights and make sure the camera output is visible to the audience.  Turn on the laser and move the zone plate in front of the beam.  Move the image plate with camera setup until the image is located.​

Demo on DimeNo
PIRA 200No
Export Instructions (if different)
HazardsNone, Light Hazard - Laser Radiation Class IIIB

​​Traditional lens material works great for refracting visible light, but the refractive index is not the same for the entire electromagnetic spectrum. For example, X-rays are only weakly refracted by glass and other transparent materials. Zone plates get around this issue, since the plate does not need to be transparent to focus the rays. The same zone plate will focus light of many wavelengths to different foci, which allows this to be a type of filter.

Category6 Optics
Subcategory6C - Diffraction
Keywordsfresnel zone plate, fresnel lens, focus, diffraction, image formation, light filter
Construction Information
laser - green, mounted to Computer lens in a wooden holder
optical component - Fresnel zone plate
image plate
camera - b&w