scientific
1
012-02675B
Interferometer
Equipment
scientific
MODEL
OS-8501 INTERFEROMETER
The PASCO scientific Model OS-8501
Michelson Interferometer is a precision instru-
ment capable of measuring the wavelength of
visible, monochromatic light with an
accuracy of better than 5%. With the
included vacuum chamber, it can also be
used for precise measurements of the index of
air refraction.
➧
CAUTION: Avoid touching all optical
surfaces on the interferometer, because
minute scratches can impair the clarity of
the interference image. For instructions
on cleaning the optical surfaces, see the
Maintenance section at the end of this
manual.
Introduction
Equipment included:
• Interferometer base with built-in micrometer
and leveling feet
• Movable mirror
• Beam splitter
• Three point adjustable fixed mirror
• Vacuum cell for measuring the index of
air refraction
• Beam expanding lens with component holder
• Fitted case
Additional Equipment Needed:
Light source: To operate the Michelson Interferom-
eter you will also need a monochromatic light source,
preferably a laser. We recommend the PASCO 0.5
mW He-Ne Laser (Model OS-9171), but any low
power laser that operates in the visible range will
work. For optimum ease of alignment, the level of the
beam should be 1.5 inches (3.8 cm) above the bench
top. Leveling screws on the interferometer allow the
height to be adjusted.
Vacuum pump: To measure the index of refraction of
air, you will also need a vacuum pump. The PASCO
Hand Vacuum Pump (Model OS-8502) is an accurate
yet relatively inexpensive pump with a built-in gauge.
It allows precise control of the vacuum level when
counting fringes. However, the vacuum chamber can
be used with any pump that can be connected by a 1/4
inch (0.64 cm) I.D. (inner diameter) tube.
➧
CAUTION: Do not use the vacuum chamber
with a compressor; it is not built to withstand
positive pressures.
Additional Equipment Recommended:
The PASCO Optics Bench can function as an aid in
aligning the interferometer. It simplifies the alignment
procedure and the magnetic pads on the bench top hold
the laser and interferometer firmly in position once the
system is aligned. A 1.0 m Optics Bench can be pur-
chased separately (Model OS-9103). A 70 cm optics
bench is included as an integral part of the PASCO
scientific Introductory Optics System (Model OS-
8500).
