Andrew Thornett

First attempt at determing frequencies of lines on my spectrum of RELCO Glow starter lamp taken with Science Surplus DIY Spectrometer

This post follows from this post in which I took the spectrum used in the analysis below:

First calibration spectra from RELCO neon starter bulb (RECLO SC 480 S53993) taken with Science Surplus DIY Spectrometer 9/9/2018

I compared the spectrum I took using my Science Surplus DIY Spectrometer of my modified RELCO SC 480 starter bulb calibration light with the spectrum found in http://www.ursusmajor.ch/downloads/sques-relco-sc480-calibration-lines-5.0.pdf

I think I have managed to identify a few of the lines.

The spectra in the image below from top to bottom are:

I have attempted to link matching lines together across the spectra.

Andy

Although I have had some success identifying a few lines above, I decided to see if I could use the Fraunhofer lines in the solar spectrum to help me identify others.

In the following post, I have tried to do this:

Calibrating spectrometers – using solar spectrum as gold standard

 

First calibration spectra from RELCO neon starter bulb (RECLO SC 480 S53993) taken with Science Surplus DIY Spectrometer 9/9/2018

The following spectra are taken using the Science Surplus DIY Spectrometer:

The spectra are from a RELCO fluorescent starter – this contains a neon bulb and in previous posts I have described how I modified this to create a calibration light for my spectrometers:

Modifying RELCO fluorescent starter to make homemade neon spectrometer calibration light part II (RECLO SC 480 S53993)

The neon bulb from the RELCO starter is much fainter than the Compact Fluorescent Light I have used previously. I needed to strap the fibre optic cable close to the neon bulb and point it directly at the bulb and also integrate the light collection over 5000ms.

Fibre optic cable and neon bulb from RELCO starter:

Settings on Spectrum Studio softeware (software that comes with the Science Surplus DIY Spectrometer) showing 5000ms integration time:

The following spectrum is from a Compact Fluorescent ceiling light in the same room – this is to demonstrate that the DIY Spectrometer is working as expected and was taken tonight immediately before the spectra that follow it:

Inverting the colours on above image (using https://pinetools.com/invert-image-colors):

The next two spectra are from the fibre optic cable pointed at the RELCO neon bulb.

Baseline spectrum with the neon bulb SWITCHED OFF:

We think that the lines above are due to hot pixels on the sensor integrated in the DIY Spectrometer or possibly dust in the slit. Note that these lines essentially disappear on the next spectrum – this is due to fact that the scale on the y-axis is quite different between the two graphs = the lines above look large but only because of the y-axis scale and in the spectrum below they are swamped by the much stronger emission lines from the RELCO starter bulb.

Spectrum with the neon bulb SWITCHED ON (so this is the spectrum of the neon bulb from the RELCO starter – neon normally only fluoresces in the red area of the spectrum but the reason these bulbs are recommended by the amateur community is that this particular brand and model contains argon as well giving lines lower down (to the left on the graph – in fact the range covered by this spectrometer at the moment precludes seeing lines in the red so we are seeing them below in blue and green and orange):

Inverting colours on above image (using https://pinetools.com/invert-image-colors):

My next challenge is to identify the lines. There is a very useful document available at http://www.ursusmajor.ch/downloads/sques-relco-sc480-calibration-lines-5.0.pdf to help me do that. The following post on Stargazers Lounge gives some pointers that might help me https://stargazerslounge.com/topic/211549-argon-lines-id-please/

More precise information on the lines in these spectra is available in these 2 data files from Spectrum Studio (these are the data files that underpin the graphs above):

DIY Spectrometer pointed at floor RELCO neon bulb OFF 090918 data

DIY Spectrometer pointed at floor RELCO neon bulb ON 090918 data

My first attempt at matching the lines in the above spectrum to their frequencies can be found on the following post:

First attempt at determing frequencies of lines on my spectrum of RELCO Glow starter lamp taken with Science Surplus DIY Spectrometer

Andy

 

Modifying RELCO fluorescent starter to make homemade neon spectrometer calibration light part II (RECLO SC 480 S53993)

This follows on from my previous post on this subject.

Modifying RELCO fluorescent light starter to create neon calibration light for spectrometry

Today, I housed the new calibration light – I put four of the RELCO starter neon bulbs in the lid of a box – I attached them to a connection block inside the box.

In this way, I have four neon bulbs ready to use. I only connected one at a time. Each bulb has life span of 90 hiurs do when one burns out, moving the wires indide the box to the next bulb along allows the calibration light to continue to ne used.

As mentioned in the previous post, I have added a boc from ebay which will turn off the light after twenty minutes preserving the life of the bulbs when I inevitably forget to turn them off on the field!

The whole set up runs on 240V via an inverter on a leisure battery. I have ordered a RCD for safety and used boxes designed for external use and sealed all holes with a glue gun to minimize moisture ingress.

My first calibration spectrum taken using the above can be seen at this post, which follows on from the above:

First calibration spectra from RELCO neon starter bulb (RECLO SC 480 S53993) taken with Science Surplus DIY Spectrometer 9/9/2018

Andy

Modifying RELCO fluorescent light starter to create neon calibration light for spectrometry part I (RECLO SC 480 S53993)

Please note this project uses potentially dangerous/life threatening 240V mains electricity supply – please ensure you are qualified to work with this or ask someone with such qualifications to do this work for you.

The following is a description of what I did rather than a recommendation for how this should be done.

My modifications required  began with my removing the neon bulb from its RELCO flourescent light starter casing and attaching 2 x 47 Kiloohm resistors in parallel to one limb of the neon bulb. The bulb is then simply connecting to 240V supply. Once I confirmed this worked, I connected a delay switch unit – this automatically switches the light off after 20 mins to preserve the life of the bulb as the neon bulbs in these starters have a life expectancy of only 90 hours each.

The delay switch unit is the box with printed circuit in the last photo – I did not make this but bought it off eBay.

All worked!

I now need to mount the bulb in a housing so it can be safely used outside for calibrating my spectrometers at the telescope.

The photos below refer to the above process.

There is a follow up post available to the above which describes the completion of this project:

Modifying RELCO fluorescent starter to male homemade neon spectrometer calibration light part II

And the following one shows the first calibration spectra taken with the new calibration light:

First calibration spectra from RELCO neon starter bulb (RECLO SC 480 S53993) taken with Science Surplus DIY Spectrometer 9/9/2018

Andy

Welding an acrylic diffuser tube for homemade compact flourescent bulb spectrometer calibration lamp

Not sure how well this is going to turn out…

Rhys and I have had a go tonight at welding two pieces of acrylic together to create a diffuser tube for our homemade calibration lamp.

Acrylic welding involves using a solvent to soften the plastic so it melts together along the weld and form a single piece of plastic.

Andy

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.

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

In my previous post, I described how I have made a device to attach my Science Surplus DIY Spectrometer to my Sky Watcher Equinox Pro 80mm Telescope using a beam splitter:

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

In my follow up posts, I described my initial experiences of using this combination:

Spectral response of the DIY Spectrometer & why I can’t detect red

Spectra of coloured LED torches & white LED & Compact Fluorescent Bulb taken using DIY Spectrometer, ATM beam-splitter telescope-optical fiber connector, Sky Watcher Equinox Pro 80mm

Calibrating DIY Spectrometer+beam splitter+Sky Watcher Equinox Pro 80mm combination 26/8/2018 using compact fluorescent light bulb

Spectra of lights in lounge using DIY Spectrometer and Sky Watcher Equinox Pro 80mm and beam splitter 25/8/2018

Today, I tried to work out the best focal distance on the Sky Watcher Equinox Pro 80mm Telescope for the beam splitter so that I optimised the signal reaching Spectrum Studio software.

Note that these experiments were done without a collimating lens before the optical fibre.

Sky Watcher 80mm Pro Telescope with beam splitter/optical fibre cable connected to computer running Spectrum Studio software:

This experiment was done using a compact fluorescent bulb at other end of room – in order to bring the intensity of the light down sufficiently to avoid plateauing out on Spectrum Studio software, I had to cover the light with a double layer of cloth:

The following photo shows the back of the beam splitter with the optical fibre cable removed – the image of the light is projected on to the white sheet of paper. I was able to move the paper until the light was maximally focused. Then changing focus on the tube until this focus point was just inside the back of the beam splitter meant I was close to maximal intensity on Spectrum Studio when the fibre optic cable was reconnected.

I found that I could change focus on the Equinox until maximal intensity was found on Spectrum Studio software. The following three photos show the intensity on Spectrum Studio with the focus tube racked in as far as it will go, at maximal intensity on Spectrum Studio and with tube racked out.

Focus tube racked in – intensity 23,000:

Focus tube at maximal intensity on Spectrum Studio – intensity 42,000:

Focus tube racked out – intensity 37,000 (starting to drop again):

The drawtube is at 46mm when Spectrum Studio shows maximal intensity:

With the focus tube set at 46mm, I then determined where the eyepiece needs to be placed in the guiding port (pointing towards us – illuminated eyepiece in it) so that it is also in focus with the focus tube set at 46mm.

 

From this I determined that I need to purchase a 1.25″ extension tube 17.4-12.9cm = 4.5cm (45mm) in length.

Spectrum taken with Sky Watcher Pro 80mm Telescope/beam splitter/DIY Spectrometer:

Spectrum from white light fiber optic calibration light source from ebay arrived 3/9/2018

Spectrum from LED white light calibration white light source – made for use with Ocean Optics spectrometers (but not made by Ocean Optics).

Andy

White light source (in gold) sitting on DIY Spectrometer (blue):

In order to attenuate the light enough to register on Spectrum Studio software with the DIY Spectrometer, I could not use the fibre optic patch cable connection as too bright – I had to use a piece of Perspex in between:

Spectrum recorded above on Spectrum Studio: