Making a device to connect the fiber optic cable from the DIY Spectrometer to a telescope & adding in some way to guide it in use – Part 1, Attempt 1

I have labelled this post as:

“Making a device to connect the fiber-optic cable from the DIY Spectrometer to a telescope & adding in some way to guide it in use – Part 1, Attempt 1”

The reason for this is that I am sure there are going to be further parts…..and equally sure I will need many attempts to get each part to work – if I ever do!


The “DIY Spectrometer”:

Changing the fiber optic cable:

First up – the cable that came with the “DIY Spectrometer” was not long enough so I needed to purchase a longer one – one that will reach from a table to the telescope eyepiece – the old cable is 50cm the new one 200cm in length – just a cheap plastic fiber optic cable from ebay with SMC connectors (the DIY Spectrometer has SMC connector on it for the fiber optic cable).

Cable that came with the DIY Spectrometer:

New cable from ebay:

Guiding the spectrometer:

In order to guide the telescope during spectroscopic observations, I purchased a beam splitter – could not find one in UK so this one came from Italy. It is 1.25 inch fitting:

For guiding purposes, I have bought cheapo variable-illuminated eyepiece off ebay again (Chinese and emphasis on cheap – 12.5mm lens in it):

Connecting the fiber optic cable to the beam splitter:

I purchased a cheap Cheshire eyepiece from ebay (again!):

I used my drill press to drill out the hole in the top of the Cheshire eyepiece so it could accommodate a SMC-SMC connector:

Drilled out hole in Cheshire eyepiece:

Drilled out hole from inside of Cheshire eyepiece:

I tried to tap the hole to fit the SMC-SMC connector (from Ocean Optics, USA):

Tapping did not work too well and I ended up with slightly too big hole so SMC-SMC connector fitted inside without needing to screwed on.

However, a small piece of black electrical insulating tape wrapped around the bottom and some Gorilla glue later and it is a tight fit and I think it should work well.

The top plate of the Cheshire eyepiece (which I have drilled to accommodate the SMC-SMC connector) unscrews – removing it shows the SMC-SMC connector projecting through the plate and an area that I was able to fill with glue from my glue gun in order to further adhere the SMC-SMC connector to the plate.


The Cheshire eyepiece has cross hairs at the front, which help it to perform its function as a collimating device:

These cross hairs do not help with its use as part of a spectroscope. They simply obscure light from a star directed at the fiber optic cable. Therefore, I removed them:

The opening at the front of the Cheshire eyepiece simply lets light in and that was no use to me so further black tape to cover the hole was necessary. I also removed the rubbish eye ring from the top of the Cheshire eyepiece:

The following photo shows the whole lot put together, with fiber optic cable attached. It looks good but will it work? I will have to see!


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