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Fresnel Zones (OP-A-FZ)

Fresnel Zones (OP-A-FZ)

As you decrease the aperture through which a laser beam travels, there is a point at which the light intensity increases.


1.  Pasco optics bench (long)
2.  Laser
3.  Pasco photometer
4.  Pasco linear translator drive
5.  Fiber optics cable  (#3, 4, 5 stored in box)
6. Slides from Pasco optics kit:
A.  Light source aperture  # 9118
B.  Variable diaphragm #9117
C.  48 mm convex lens  #9133
D.  18 mm convex lens  #9132

(Approx. positions shown below)

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  • Description

    Product Description


    1.  Set up as shown.  Line #9118 up so that the beam goes through one of the apertures.  Adjust the top knob on #4 & the sensitivity knob on #3 until you get about a half-scale deflection on #3.
    2.  Slowly close the diaphragm, watching the intensity scale of the photometer.  With proper adjustment of positions of the components you should see the  intensity gradually decrease as you close the  diaphragm.  But watch carefully–at one point the needle will rise, indicating an      intensity increase.

    Caution:  Don’t bend the fiber optics cable — it is sensitive to flexing.