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Re: High speed rotating mirrors



A surplus gyroscope driver is much less expensive. When we modified the UCSC
(Physics) speed of light experiment, I removed (painted it with Kodak optical
black) the second mirror, as it was not sufficiently parallel with the other.
The total (operative) path length was 20 meters. I believe the motor/ mirror
was Leybold's.

bc

If I remember correctly, long path length will compensate for slow speed. My
memory "says" ours was only 6,000 RPM. I suspect the motor whine at 28,000 is
supersonic; is yours? At top speed ours was ~ top note of a piano. (memory
from ten years ago)

Herbert H Gottlieb wrote:

On Sun, 19 Nov 2000 13:41:47 -0500 "Tom and Sandy Habowski"
<Habowski@ptd.net> writes:
Hello, I am a high school science teacher and I got your name from a
metrologic rep at the NSTA conference. Do you sell multi-sided
mirrors for high speed rotation and measurement of the speed of
light? thanks for your reply, Tom Habowski

Tom..
The Metrologic laser company has motor mounted
4-sided mirrors that they use for scanning bar codes.
However, these would not be suitable for measuring
the speed of light for two reasons. The motors
are much too slow for your purpose and each of the
four mirrors is mounted at a slightly different angle
to enhance bar-code scanning.

The old standby apparatus to measure the speed of
light with rotating mirrors is manufactured by
the Klinger Educational Products Corp.
112-19 14th Road
College Point, NY 11356
www.klingereducational.com
Their apparatus (KE4401) contains a 110V ac motor that
rotates a two-sided metalized, quartz-coated mirror
at 28,000 rpm. Back in 1980 it cost about $800
and is probably a bit higher today.

Another high-speed rotating mirror (No. OS-9263A) for
measuring the speed of light is available from:
Pasco Scientific
10101 Foothills Blvd.
Roseville, CA 95678
www.pasco.com

In the current 2001 Pasco catalog their high-speed
rotating mirror lists for $1537.00

I used the Klinger apparatus a few years ago at
the University of Arkansas and was able to measure
the speed of light within 5% of the standard value.

The Pasco apparatus is new and I have not tried it
yet. But I expect that one could obtain the same accuracy
(+/- 5%.) Perhaps others on this e-mail list can furnish
additional sources for high-speed rotating mirrors.

Herb Gottlieb from New York City.
(Where high-speed rotating mirrors are wqay too expensive
for most of our high schools.)

herbgottlieb @juno.com