Science-Surplus “DIY Spectrometer” and Spectrum Studio software

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

 

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:

How to process spectra recorded from the Science Surplus “DIY Spectrometer” using the “Spectrum Studio” software in either Microsoft Excel, RSPEC or VSPEC software

How to process spectra recorded from the “DIY Spectrometer” using the “Spectrum Studio” software in either Microsoft Excel, RSPEC or VSPEC software.

The following is my summary and my own screenshots of the process using a solar spectrum I took using the DIY Spectrometer. I am indebted to Jeffrey L. Hopkins’ excellent book for teaching me about the process “Using commercial amateur astronomical spectrographs” and is the only resource that I know of that explains how to do this.

Processing the results from the DIY spectrometer in Excel, RSPEC, VSPEC:

Spectrum line profiles generated from the DIY spectrometer using its own software Spectrum Studio can be saved as a CSV file. Later we need to convert it in to a text file, once we have manipulated it in Micosoft Excel or Open Office or other similar spreadsheet programme.

Saving profiles from Spectrum Studio:

As shown in the screenshots above, Spectrum Studio automatically saves as CSV file which can then be directly loaded into Excel.

The CSV file produced includes a header with the scan date which uses the computers date and time, integration time which is the same as exposure time, and number of averages.

The following screenshot shows the Spectrum Studio CSV file as generated by Spectrum Studio opened in Microsoft Excel. I have highlighted the header:

Five columns of data will be found below this header.

Under the five columns are 2047 rows of data corresponding to the 2047 pixels on the linear CCD chip. Each row has an associated column for pixel number, wavelength in nanometres, sum, average, background. If the spectrum has been calibrated then the pixel number and wavelength will be the same.

The CSV file that is been saved above can be opened in Excel. Only two columns are needed for further analysis – the pixel number and the sum.

The following screenshot shows the Spectrum Studio CSV file opened in Excel with the Pixel Number and Sum columns highlighted – these are the two columns that need to be kept in order to open the file in RSPEC/VSPEC – other columns are deleted as is the header:

To create a line profile in Excel or Open Office or other similar spreadsheet programme, select these two columns and choose the desired graph from the options open to you in the spreadsheet software. The data files of multiple columns of ADU counts, Microsoft excel can be used to produce another column which is the sum of those counts for a given pixel position. That sum and pixel position can be used to create the line profile graph. The pixel number versus the wavelength can be determined and a new column created that shows the wavelength for each pixel position. The sum column and the new wavelength column can then be used to create a wavelength calibrated line profile graph. Such a graph would be very similar to the one that appears on the DIY spectrograph’s own spectrum software when you take spectrum.

Microsoft Excel helps allows you to manipulate the file so that it can be loaded in RSPEC/VSPEC but programmes such as RSPEC or VSPEC are easy to use if you want to process the spectrum in practice.

In order to open the text file from the DIY spectrograph spectrum in RSPEC or VSPEC, some changes need to be made to this text file. Open it in Microsoft Excel and then:

1. Delete the header data
2. Delete the column titles
3. Delete all columns except pixel number and sum
4. Save the resulting file as a text file. It does not matter from my own experience whether you save as Unicode text file or as tab-delimited – both with open in RSPEC/VPSEC.
5. Change the extension from .txt to .dat

The file can now be opened in RSPEC or VSPEC.

This file is not an image file any longer so it must be opened as a line profile .dat file.

Opening profile in RSPEC:

 


Once opened in RSPEC or VSPEC the profile can then be wavelength calibrated and further processed.

Resources and video tutorials online for use of Science Surplus DIY Spectrometer

The following resources are available on-line:

Company webpage:

Main webpage: http://www.science-surplus.com/products/spectrometers

Resources for Spectrometer: http://www.science-surplus.com/products/spectrometers/spectrometer-resources

Youtube video showing recording spectra from specific metals is sparks and also gives some detail on use of ability in the software to explore specific atomic lines on the spectra:

Other we based resources:

http://redlum.xohp.pagesperso-orange.fr/electronics/spectrometer.html

http://www.thepulsar.be/article/science-surplus-spectrophotometer-review/

https://www.photonlexicon.com/forums/showthread.php/24623-Science-surplus-spectrometer-calibration-help-needed

https://stargazerslounge.com/topic/204245-diy-spectrometer-first-light/

Solar spectrum taken at LRO 26/8/2018 using DIY Spectrometer

Having calibrated my DIY Spectrometer, I took a solar spectrum by pointing the telescope at the cloudy sky outside LRO.

I have compared the spectrum below to a published spectrum.

It shows many prominent lines. Unfortunately, it also shows that my calibration was off – the red lines should be vertical!!!

Andy

Comparing spectra when spectroscope pointed at garden and at sky above garden (DIY Spectrometer)

I decided to compare the spectra when I pointed the spectroscope at the grass in the garden as opposed to pointing it at the sky. The sky gives a solar spectrum (cloudy today).

Please note that after posting the following, I later discovered that there were some significant errors in the calibration values obtained here, although this does not affect the main lessons of the post re spectra from pointing at garden vs. sky – see https://roslistonastronomy.uk/solar-spectrum-taken-at-lro-26-8-2018-using-diy-spectrometer

Andy

The following spectra were taken using the optical cable from the DIY Spectrometer connected to its modified Cheshire attachment but WITHOUT either beam splitter or telescope being used.

They both show the solar spectrum but the intensity on the y-axis is nearly 20x as high when pointed at the (cloudy) sky than at the grass – I did not expect this degree of difference as although I say it was pointed at the grass it was only vaguely in that direction and I would have expected large amount of light to have got in any way. The modified Cheshire does only allow reasonably collimated rays of light to get in to the optical fibre which would amplify this effect. The higher intensity solar spectrum when pointed at the sky is also a lot cleaner with less noise.

With optical cable pointed at the grass in the garden:

With optical cable pointed at cloudy sky above garden:

The following spectra were taken using the optical cable from the DIY Spectrometer connected to its modified Cheshire attachment which was then attached to Sky Watcher Equinox Pro 80mm via beam splitter (so this is with telescope).

With the telescope and beam splitter, I needed to use longer exposure times. Note that with cable alone above I only used 50 ms. The exposure time when using the telescope and beam splitter and with the combination pointed at the garden required a lengthy 60,000 ms to obtain the spectrum below. I got away with a lower 500 ms when pointing the telescope at the sky.

Although requiring a longer exposure time with telescope than with optical cable alone, when pointing both at the sky excellent clean solar spectra are obtained.

The telescope pointed at the garden does have the features of the solar spectrum in it but they are largely swamped by noise.

Note that these spectra are all taken during DAYTIME.

With telescope pointed at garden:

With telescope pointed at sky above garden: