Black image after assembly
Hi, all! I'm greatly looking forward to helping out with spectrometry.
I'm using the kit, and followed all instructions. Everything seemed to go fine. I removed the IR filter, refocused using a bar code at 9", and completed assembly.
But now when I focus my spectrometer at a CFL bulb at 9", all I get is a black image. If I bring my spectrometer up to 1" from the bulb, I simply see a vague white smear on one side.
Pictures attached. Anyone have any idea what I may have done wrong?
PDF version
Comments
Brent,
It might be that you need to adjust the alignment of the camera. The relationship among the slit, the grating, and the camera is critical to get an image of the spectrum projected precisely into the camera's lens.
It looks like you are viewing the live video image from the webcam. While doing that, just reorient the camera (with grating attached) until the spectrum is centered in the image and the lines are vertical. Make sure you are viewing the brightest spectrum and not a dimmer secondary spectrum. When you get a clear, tidy image, lock down that orientation and you should be ready to go. If you can find no image of a spectrum, maybe the grating (DVD) is positioned incorrectly.
You can also post at the plots-spectrometry Google group where more experienced people might be able to help.
Chris
Thanks, cfastie! I'll try that. I'm getting no spectrum at all right now.
Try looking at the cfl bulb directly with the cover off to see if the camera is working right. If you get a bright light doing this, then you most likely have an alignment problem. I get the brightest signal on mine when I keep my light source about 5-10 degrees to the left of center when I shine it at the source due to a minor misalignment on my part. It works fine that way since I am manually line up any absorbance readings anyway. Play with the light anlges while the spec sits level on a flat surface and see if that helps?
Hi Brent,
Did you end up fixing the problem you described? I have exactly the same problem. Pointing my camera directly at a light source shows a white image, so I know that's working.
I've spent a while trying out different angles for the camera, but the light is just not getting to the camera in the case.
Thanks.
mnc: I haven't had a chance to fix the spectrometer yet, but I think I know what's wrong: the CD fragment I received was slightly discolored in places. I tried to cut out a normal area, but I may have used a discolored one, as I couldn't tell which was the correct coloration.
I'm going to grab a blank CD of my own and cut out a piece of that.
mnc, did you figure out your problem too? Brent - sorry to hear your DVD-R fragment was damaged. We tried to protect them by putting them in baggies, but i guess something went wrong. From your more recent note it looks like you figured it out thought. Glad to hear it.
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