Observing Diffraction

We will need an optical bench, a laser, a single slit slide, a photometer aperture slide, a 48 mm lens, a linear translator with a photometer probe and a photometer.

Name:

Lab Partners:

When entering numeric data, use exponentials: ie., 1.6 * 10-19 = 1.6E-19.

Procedure

  1. Make sure the photometer shutter is closed. With the laser and linear translator at opposite ends of the bench, align the beam so that it is parallel to the bench and enters the photometer probe. Place a component carrier in between them, with the slit slide on the laser side of the carrier, and the lens on the other side. Place the aperture slide on the translator so that the 0.1 mm slit crosses the center of the beam. The slit should be 48 mm from the center of the lens.

  2. Open the shutter. Vary the position until the central maximum of the diffraction pattern is found. Scan the pattern, turning the position knob in the counterclockwise direction, and record intensity vs position. Work quickly as the photometer sensitivity varies with exposure:
    x1 = I1 =
    x2 = I2 =
    x3 = I3 =
    x4 = I4 =
    x5 = I5 =
    x6 = I6 =
    x7 = I7 =
    x8 = I8 =
    x9 = I9 =
    x10 = I10 =
    x11 = I11 =
    x12 = I12 =
    x13 = I13 =
    x14 = I14 =
    x15 = I15 =
    x16 = I16 =
    x17 = I17 =
    x18 = I18 =
    x19 = I19 =
    x20 = I20 =
    You MUST have all 20 data points; they should cover from the central maximum to the second minimum on one side of the central maximum.

Analysis

  1. Carefully plot the data from step 2 on a graph; use symmetry to fill in the "other" side of the plot.

©2004, Kenneth R. Koehler. All Rights Reserved. This document may be freely reproduced provided that this copyright notice is included.

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