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- Set up spectrometer to find and record spectral lines of lamps. Focus frames such that we find the best values for the distance from the camera to the lens, the angle of the grating, the angle of the camera and the distance of the optical fibres to lamp.
- Initial temperature set approx 7 deg.
Cadmium lamp
- Exposure time 0.1s, Camera taking continuous data
- Angle of grating:
- started with micrometer at 10mm, decreased in 1mm intervals. At 5mm, decreased in 0.5mm intervals. At 3.5mm, decreased slowly until 2 bright and 1 dimmer out of focus lines appeared on frame.
- Distance from camera to lens:
- started at 25mm, decreased in 1mm intervals. At 21mm, decreased in 0.5mm intervals. At 19.5mm, image started defocusing again, so we then increased in 0.2mm intervals. At 20.1mm, we achieved the best focus distance.
- (Note to self: Everytime we focus such that distance increases, remember to check camera is pushed forward).
- Camera angle:
- started at 2.5mm. At 3mm, increased in 1mm intervals. At 7mm, we achieved the best camera angle.
- Once we achieved focus, we altered the angle of the grating so that the 3 lines were centred in the frame. At 3mm, we achieved the best grating angle.
- Distance between optical fibres and lamp:
- At a distance of 195mm - used Graph Window GW -> Horizontal line to plot the spectrum. Found maximum pixel value to be approx 29,000 - not saturated, but still very bright. We found this to be a good distance.
- Changed the distance to 100mm - used GW, maximum pixel value approx 46,000 - approaching/partial saturation.
- Changed distance to 50mm - used GW, maximum pixel value approx 48,000 - definite saturation.
- At 200mm, we achieved the best lamp-optical fibre distance.
- We found that the spectral lines seemed to drift upwards from left-right. We therefore rotated the fibre optic input at the back of the spectrometer. We began by rotating it approx 90 deg to see the outcome. Ultimately, we found rotating this alone did not change the drifting. We then adjusted the camera angle and fibre optic input angle simultaneously, such that the spectral lines were completely aligned.
- For the best image, we found the camera angle should be at 3.5mm, and the 'spectrometer' label on the fibre-optic input should be vertical.
Halogen lamp
- Exposure time 0.1s; camera angle, distance between camera and lens, optical fibre input remained kept in same configuration, however we altered the angle of grating.
- Moved the optic fibre away from lamp, distance between them approx 705mm.
- Image displayed many spectral lines, however horizontally rather than vertically.
- Used GW -> vertical line
- Changed distance between fibres and lamp to 300mm. GW showed max pixel value approx 11,000 - far from saturation, but still very bright lines.
- Distance = 100mm, max pixel value approx 43,000 - approaching saturation
- Distance = 50mm, max pixel value approx 49,000 - definite saturation
-- Public.AshleaKemp - 09 Oct 2015
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