So what is it about
As we know there are primarily two types of barcode scanners - CCD based and Laser based. CCD based essentially contains a CCD to take a digital 'pic' of the barcode and processing it. They are obsolete now, as there must be a physical contact between the scanner and the barcode. Laser based contains a optical assembly which uses a laser beam that scans the whole barcode region with a help of a rotating mirror; a focusing mirror is used to focus the beam onto a photodiode.
Come to the point man!
So, if we can replace the rotating mirror with a piece of reflection grating (or simply paste a grating on the mirror) we already have what we need - grating, focusing mirror, detector. All we need to make is a slit, which can be easily done. I can't do it as I dont have experience of hacking electronics but I believe this is achievable by someone who could play with arduino and stuff.
How expensive is it to get the front reflection mirror? Can it be made by normal silver salt dipping method (using for conventional looking mirror), and not painting it with a protective paint? I guess that would be very cheap method if its possible.
Is there anyone who would like to partner with me for a project of this kind - making a pocket-sized spectrometer. I am looking for someone adept at electronics (and may be MATLAB too).
About the image
It shows the optical assembly. Golden colored metal is the laser, copper colored is the motor, golden colored glasses are mirrors - plane and focusing. Steel-type container in the left side of the above image contains the photodiode.
Aha! Those marked up photos help a great deal! Thanks @shubham.
Your answers are not at all half witted. I just asked in case you happened to know and because I am interested.
I had in mind a rotating barrel mirror as compared to a pivoting flat mirror, so the mark-up is very helpful.
Here is one more question for you: What brand/model of bar code reader did that assembly come out of? That might help provide some clues as to what the components are and where specifications might be found.
Based on what I see there, the drive motor looks like it might be just a magnetic inductor that pulls the mirror across it's full movement.
Is there any obvious physical connection between the drive motor and the pivoting mirror?
Is there a spring type return to move the mirror back to a 'default' or 'home' position?
Just trying to figure out the what would drive that mirror back and forth from a mechanical perspective and at what speed it might traverse the length of its travel.
As I mentioned, I am not all that familiar with the guts of a spectrometer: So I have a question....
Assuming that you will use the pivoting mirror as is (same dimensions), how tight of a grid would have to be placed on it to make it useful for distinguishing between frequencies? Would one really need a grid? If one knows the position of the pivot mirror relative to the focusing mirror, does that not indicate the prism effect and therefore allow one to determine the frequency of light focused on the detector? Like I said, I am rather ignorant of the theory here, so thought I would ask you to help educate me a bit.
I am wondering if instead of pulling that assembly apart and using it's components, one might be able to figure out a way to use it as assembled. If the detector is capable of distinguishing and responding to all the frequencies of the visible spectrum (or most anyway) and the focus mirror is already all lined up, then the only thing one might have to do is find a way to get tight control of the movement of the pivot mirror and replace the diode with the light access slot that you mentioned.
If you can provide that make/model of the original unit, and are willing to share, I would like to see if I can find a similar one and play around with the existing electronics a bit. There must be some signal processing already going on there to distinguish the light/dark areas on a bar code and turn that info into a digital representation of the bar code. That in itself might be useful to understand. There are two chips showing on the upper side of the PCB that might lead to some pretty good clues about how the processing is taking place already....
Just a thought....
Thanks for indulging me! Your project is intriguing... :-)
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