# The Projecting Microscope

Document Sample

```					          The Projecting Microscope

A sample presentation by
Chuck Rogers,
Dept. of Physics, CU-Boulder

1/25/10              Projection Microscope   1
Major Goals
• Learn how to use the optics lab room
equipment.
• Hit the high points of observing and
understanding laser beam properties and
diffraction.
• Design a 400x projecting microscope
• Build the microscope and verify its
behavior.

1/25/10                 Projection Microscope         2
The Optics Lab

•   What’s in the cabinet?
•   Setup the laser on the optical rail.
•   Fiddle with Ronchi and lenses.
•   Learn how to find lenses.
1/25/10                 Projection Microscope   3
Ronchi Grating (a spatial square wave)

Measuring microscope view of            Diffraction pattern through the Ronchi. Shows
the Ronchi grating. A ten period        only odd orders, consistent with a square wave.
average shows a square wave            15 fringes covered 68 ± 1 mm and the screen
period of 254 ± 3 microns/line.        was 1840 ± 5 mm away so tan(q) = 0.0370 ±
0.0006.
Diffraction theory predicts l=d Sin q /N which gives
Measured laser wavelength: 627 nm +/- 13 nm
Although only a 2% measurement (13/627),
it is within 1% of the true wavelength (632.8 nm)
1/25/10                        Projection Microscope                            4
Design of the 400x Projection Microscope

4x beam expander. Used
Lx1 f.l.=25mm and lens          Two magnification stages of
Lx2, f.l.=100mm                 equal mag of 20x
Built with equal focal length
lenses f.l. = 50mm

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Sample images

High resolution image of a single atomic
state imaged with our microscope.

1/25/10                   Projection Microscope      6
Diffraction limits of resolution

Modest choppiness on the image due to finite
laser wavelength. We saw no effect from the iris
because we put it in front of the beam expander
rather than the first lens….

1/25/10             Projection Microscope      7
Summary
• Learned how to use the optics lab room
equipment.
• Hit the high points of observing and
understanding laser beam properties and
diffraction.
• Designed a 400x projecting microscope
• Build the microscope and verified its behavior.

1/25/10                   Projection Microscope           8

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