Effect of adding collimating lens in front of optical fibre behind beam splitter Science Surplus DIY Spectrometer/Sky Watcher Equinox Pro 80mm

I purchased a second hand Ocean Optics collimating lens from ebay and tried adding this into the optical train to see what difference this made to the intensity of the signal on Spectrum Studio software from the DIY Spectrometer. Theoretically, it should result in a stronger signal.

This follows from my previous post where I determined best focusing distance:

Finding the focus distance for Science Surplus DIY Spectrometer/beam splitter combination (without collimating lens) in Sky Watcher Equinox Pro 80mm Telescope

Ocean Optics collimating lens:

Collimating lens attached to optical fibre cable:

When I removed the end of the Cheshire eyepiece that I was using to attach the optical cable to the beam splitter, I found it was threaded and the collimating lens could screw into this.

 

For comparison, the following image is of the optical cable connected without collimating lens:

Spectrum from the DIY Spectrometer when the optical cable is attached without the collimating lens:

Spectrum from the DIY Spectrometer when the optical cable is attached with the collimating lens:

The intensity is over twice as much with the collimating lens, when the telescope is pointed at the same light on the other side of the room.

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