Still messing about with fibre optic cables - after all these years.
This blog entry is in two parts both of which are spectroscopy related!
With the weather over my house being 'changeable' to say the least, I have been doing a bit of sporadic spectroscopy. I find spectroscopy very interesting but like 'statistics' in mathematics I am always lacking in confidence as to my results. Recently, I have been trying to obtain a low resolution spectral profile of Arcturus. I used Castor as a calibration star and to obtain a response curve. I know Castor was in a different part of the sky than Arcturus but at least it was captured using the same set up on the same night. The calibrated wavelength profiles looked ok to me but when I applied a response correction curve the result seemed far from convincing when compared with the Miles Arcturus reference. I have attached my charts prepared using the excellent BASS software. Any helpful comments would be appreciated.
As this forum is 'chocker' with knowledgeable folk, might I run this concept passed those that are considerably smarter than I am!
I have been trying to make a small plug in unit to attach to the telescope end of my very simple transmission grating spectrometer. The concept being; that I could transform my 'slit-less' spectrometer into one that uses a line or ring of small diameter fibre optic cables to take light from say a bright nebula or an extended object like a planet and present the light in star like points (neatly avoiding pinhole camera issues). As planned this 'simple' arrangement would not involve additional collimator and camera lenses.
To date I have had a couple of goes at making such a 'gizmo' with no success. My failure could be for a number of reasons:
- The concept is wrong and doomed to failure.
- My engineering skills are 'dodgy' - to be honest this is a given but has not held me back so far.
- My choice of fibre optic cables has been inappropriate (ie. diameter, sheathing and type). Up to now I have been using 9 micron fibre in a 1mm sheath.
Being old and obstinate, it is unlikely that I will give up soon. I should be grateful for any advice. In particular if the concept is flawed - changing my approach would ensure that I spend more 'quality' time with my wife.
Please be gentle with me as I am qualified in the arts rather than sciences and my engineering qualifications are limited to the shared ownership of a shed and tools of the more basic nature mainly acquired from Lidl's centre aisle !
George in a surprisingly 'sunny' Lowestoft - I must find my sun hat and shorts! - No the clouds are back - so pass me my balaclava helmet Anita.😶🌫️
Ps.24-05-2024 - Think I may have identified the problems associated with the Arcturus profile. I believe it is a miss-match of capture crop size. When you look at the bottom profile I would expect the Arcturus profile to be further to the right compared with the Castor profile. I have subsequently upscaled (resized) the image capture for Arcturus using BASS software and things look better. Note to self when capturing spectra keep the crop size consistent between target star and calibration star. (Even if I am not right about this, it is one less variable to juggle with!🤣)
Edited by Hawksmoor
Idiocy
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