An inexpensive, simple-to-build, scanning Fabry-Perot interferometer using commercially available parts is described. We discuss an experiment to measure the interferometer's finesse and we discuss the effect of non-ideal mirrors on instrument performance.

1.
T. T.
Grove
, “
A low-cost scanning Fabry-Perot cavity for laser experiments
,”
Am. J. Phys.
71
(
2
),
184
185
(
2003
).
2.
Colin D.
Fletcher
and
Chad
Orzel
, “
Construction and calibration of a low cost Fabry-Perot interferometer for spectroscopy experiments
,”
Am. J. Phys.
73
(
12
),
1135
1138
(
2005
).
3.
Joseph C.
Amato
,
Roger E.
Williams
, and
Hugh
Helm
, “
An inexpensive, easy to build Fabry-Perot interferometer and its use in the introductory laboratory
,”
Am. J. Phys.
59
(
11
),
992
994
(
1991
).
4.

Thor Labs, Edmund Optics and Anchor Optics supply plate beamsplitters with many available beamsplitting ratios priced in the range $40–$120.

5.
Frank
Pedrotti
,
Leno S.
Pedrotti
, and
Leno M.
Pedrotti
,
Introduction to Optics
, 3rd ed. (
Prentice-Hall
,
Upper Saddle River, NJ
,
2007
), chapter 8.
6.

Interferometer A used mirrors from Edmund Optics #31-435 ($40 each), interferometer B used Anchor Optics mirrors (similar to currently available AX46611, $42 each), and interferometer C used Thor Labs BSX10 ($115 each). The complete instrument assembled with the following Thor Labs parts [BSX10 mirrors ($230), mirror mounts KM100 ($39), translation stage PT1 ($264), and piezoelectric actuator AE0203D08F ($80)] costs $652, substantially less than a commercial unit.

7.

We used Vernier Software's MPLI (Multipurpose Laboratory Interface).

8.
Yeh
Pochi
,
Optical Waves in Layered Media
, 2nd ed. (
Wiley-Interscience
,
NY
,
2005
).
9.
CVI/MellesGriot Technical Notes “Optical coatings,” <https://marketplace.idexop.com/Frontend/PDFs/optical_coatings.pdf>.
10.
D. L.
Ford
and
J. H.
Shaw
, “
Rapid method of aligning Fabry-Perot Etalons
,”
Appl. Opt.
8
(
12
),
2555
2556
(
1969
).
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