Cornell Plate Double-Slit Interference - Physics Demonstrations - Cornell Plate Double-Slit Interference | Physics Undergraduate Labs

Use only Class 2 (< 1 mW) or Class 3R (1-5 mW) lasers for this demonstration. Never look directly into the laser beam or its specular reflections. The reflection shield prevents back-reflections toward the audience. Inform students before turning on the laser and establish a safety perimeter around the beam path. Post appropriate laser warning signs if required by your institution.

Purpose

A laser illuminates double slits on a Cornell plate, producing an interference pattern on a distant screen. The Cornell plate has multiple slit configurations (varying separation, width, and number of slits) for systematic exploration of interference and diffraction.

Green laser passing through Cornell plate mounted on ring stand with finger clamp, producing a horizontal interference pattern on white paper magnetically attached to blackboard

Cornell plate diagram showing three sections: variable spacing with constant width, parallel slits with varying width, and single slit with varying width, with slit separations ranging from 0.033 mm to 1.40 mm

Figure 1: Setup showing laser, Cornell plate on ring stand, and double-slit interference pattern projected onto paper on the blackboard. The bright central maximum and symmetric fringes are visible.

Figure 2: Cornell plate layout. Sections include variable spacing (constant width), parallel slits (varying width), and single slits (varying width), with separations from 0.033 to 1.40 mm and configurations from 1 to 15 slits.

Optical Slider

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Polished Steel Plate

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Safety Warnings

Warning: Laser Safety - Class 2 or 3R

Purpose