only me (via him) <dont at even.ask.com> wrote in message
B7E0FE79.285B%dont at even.ask.com...
>I have recently acquired an optical instrument which appears to be a
>>It is labelled "Watson x2 patent pending"
>>it has a 10x microscope eyepiece looking at a square graticule, and an
>optical input via a long black bakelite cone which clearly drops into a
>tube, possibly a microscope.
>>Inside are some very high quality optics dividing the beam with a 45degree
>dichroic mirror, creating two alternate paths, one green, one red.
>>A very accurate micrometer slides two mirrors to vary the two path lengths.
>>A counter-type mechanical readout gives readings from about 0 to 110, the
>path lengths being equal (interference fringes visible) at around 40 units.
>>Slide travel is about 4mm with readout to 0.05 units easily ie one part in
>>It is in a cream enamelled body.
>>Anyone any idea what it is ?
>>Thorough internet search reveals nothing