Viewing 6 posts - 1 through 6 (of 6 total)
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  • #10043
    xenon
    Participant

    Hello,

    My language is USA English. I participate on this forum using MS Win 10, ‘EDGE’ browser. EDGE has a built in translator from Italian to English. Only about 90% of the words are translated. The buttons and icons are typically not translated. For example, the button on the register page does not translate. It displays a series of Greek letters. It looks like a funny math formula. After sending some emails to the site maintainers, I continued to try to register and login. Today I succeeded!

    I would like to share my progress with building the Theremino Spectrometer: I bought the following parts:
    * webcam for about $9USD. The sales specs were HD, 5 MP, 1040×1040 pixels, CMOS, sensor.
    * 2″ (50.8mm) x 18″ (457mm) cardboard mailing tube. Each end has a white ‘diffuser’ stopper on it
    * Open cell foam (maybe non-static)
    * DVD-R blank writable disk

    I was able to get a spectrum by taping and holding all the components together. This method provided insight into all the various relationships required to get a spectrum. It’s very difficult to align the whole system. During the alignment process, my win 10 computer crashed several times. Eventually, the wires on the webcam broke completely off. I resoldered them and glued them onto the pcb to provide extra strain relief.

    After several days of soldering and glueing, I tried to align the system and get a spectrum. I taped the webcam to the foam at about 30 deg and stuffed it into one end of the mailing tube. On the other end was the white plastic stopper. I put 2 pieces of black tape on it to form a slit similar to the Theremino build instructions. I pointed the end of the tube within about 2″ (50mm) of a CFL lamp and got a stable spectrum!

    I used my own method to focus and align the grating. I will describe that later.

    Also, I tried to make a donation but it didn’t work.

    Great Resource!

    I hope that you guys will be around for a while

    #10045
    xenon
    Participant

    Tried to calibrate the spectrum using a CFL as in the instructions. My displayed spectrum has the same shape but can only align either the 436 or or the 53x (forgot exact number) marker. The whole spectrum ( violet to red) lies on the right side of the ‘box’. I tried to use the start X, end X boxes to center but that didn’t work. I tried moving the webcam in the tube but that didn’t move it to the left much or at all. I can only get the spectrum to rotate.

    I tried to push the webcam farther into the tube but could only push a few inches (50mm) using my fingers. If the webcam is not at the end, I lose sight of it in the Theremino display box and it is hard to manipulate the webcam so that the spectrum displays again.

    Question, is the tube too long?. It is 18 inches which is 457mm. Would shortening the tube move the displayed spectrum to the left on the Theremino display?

    #10047
    Picmicro675
    Moderator

    I can, for instance, write in English, but my grammar might be horrible. I hope that Theremino will be at the same level and he will give his explanation. Unfortunately I don’t have much experiences with the Theremino platform, in order to give you some idea.

    #10049
    theremino
    Keymaster

    The webcam should not be “pushed forward or backward”, it should be rotated with respect to the right axis.

    You have to follow the instructions and the pictures of the instruction files that you download from this page:
    https://www.theremino.com/en/downloads/automation#spectrometer

    In particular the following PDF:
    https://www.theremino.com/wp-content/uploads/files/Theremino_Spectrometer_Construction_ENG.pdf

    On the first pages you can see how the webcam must be mounted, and in the page 10 you can see how it must be rotated about 30 degrees.

    Furthermore, be careful that it must be rotated on the right plane and that the rotation should be modifiable if the spectrum is too far to the left or too far to the right to be able to perform the software calibration operations.

    #10550
    xenon
    Participant

    Update on my spectrometer build:
    Mounted webcam in a small cardboard box. I screwed cam to side of the box so that it could be rotated. I cut a 2″ hole in the box and inserted the cardboard mailer tube. On the end of the mailer tube is a translucent, white plastic ‘stopper’. I put black electric tape over the stopper to make a thin rectangular aperature. The tube aperature was in line with the webcam aperature. It is hard to describe the angles but they were similar to that recommended in the theremino instructions. All construction was very crudely done.

    I was able to ‘calibrate’ the spectrometer using a CFL buld placed right at the mailer tube aperature. The spectrum was ‘boxed’ by rotating the tube aperature with respect to the webcam aperature and adjusting the ‘Y’ value. It was difficult getting used to the calibration procedure. I found that aligning the low end first was the only way to get the scales aligned at both low (left) and high (right) ends.

    I verified cal using a 650 nm red LED laser : it peaked right at 650! I had some other light emitters and those seemed to match the assumed wavelengths. I measured down to about 395nm

    With very crude construction held together with ‘scotch’ tape, it was difficult to get a measurement. It’s works well with a very bright CFL placed rigth at tube aperature but the 650nm red LED was almost too dim to create a specturm. It appeared very faintly on the software raw spectrum display. It also seemed to depend on the angle of the LED laser beam with respect to the mailer tube.

    However, I was very glad to be able to measure an optical spectrum. This will be very useful! . I would like to know if there is a reliable light source to check measurements below 395nm and perhaps as low as 200nm?

    One last thing. I was wondering if there is an update to the Theremino Spectrometer software and I believe the answer is yes according to the recent posts here.

    Great work guys!

    #10552
    theremino
    Keymaster
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