Wk2–Divergence and Spatial Resolution Abbreviations:
b/w = between
Sunday, October 11, 2020 1:23 AM w/ = with
V = voltage
I = current
D = displacement
R = resistance
• Collimated source: all particles travel in the same direction.
○ Quantified by the beam divergence-- angular spread of the beam.
Lab Report Notes
○ If all particles are parallel, divergence is zero.
• (Part of 2.3.2) Determine how the light intensity varies as a function of
○ A laser beam essentially. But, no light source is completely collimated.
distance. We will use two different light sources (a desk lamp and a laser).
• Isotropic source: emits particles uniformly in all directions, having the largest divergence possible.
• Instead of focusing on signal-to-noise ratio, it is more important for the source to be collimated, so
that energy isn't being wasted by spewing all particles into space.
○ Is the theory and the experiment consistent with eachother? On a
• Conclusion: Does the laser or lamp re-create the slit better? The laser does b/c it's light particles
graph, you can see that the normalized and theory desk lamp, as
(photons) are focused in one spot. The lamp light source diverges as it light particles spread out.
well as the Normal and Theory laser are consistent in trend, but
• Remember to subtract the background (1V showing up, then 4V shows on the DMM after light
not in exact numbers.
source shines: 4 -1=3).
○ What should the theoretical prediction be for the laser? The
• Spatial resolution set-up: Source: laser or lamp, Detector: photometer. Shine the source onto the
theoretical value of the laser should be "1" each time.
slit; light gone through hits the detector and gives a voltage reading.
○ How does the laser differ from the desk lamp? Why? As the distance
○ Converts light readings to voltage measurements.
between the photometer and laser decreases or increases, the
amount of photons detected should remain the same because it is
Lab Section 2.3.2:
a relatively collimated source; all light particles travel in the same
Purpose: verify that the desk lamp loses it's intensity as 1/r^2, but the laser doesn't lose intensity w/
direction and are thus focused on the same spot on the
distance (r). -> 1/r^2 doesn't apply to laser.
photometer. A desk lamp is a isotropic source, meaning it emits
• Use the lamp first, then laser w/ the same setup.
photons in all directions and the particles become more spread
• Drawing: just make labeled boxes. <-- [Desk lamp or laser]
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