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Spectroscopy

For me it all started with the High Pressure Mercury Vapor lamp. I started collecting light sources that emitted different linear spectra at the age of 14. Today my lamp collection has around a hundred High Intensity Discharge lamps.

Later I started experimenting with various raw metals and DC arcs, and examined the emission spectra on a small hand held spectroscope that my father bought.

The need for a more detailed spectrum became more intense, so I set forth and built a more powerful spectroscope, the Phasmatron Spectroscope. After i finished the designs I gave it to an engineer to build it. It weighs 35kgs, and has a resolving power of 50,000 in the area of the blue mercury line.

Phasmatron Spectroscope:

The main theoretical problem with the Phasmatron spectroscope was deriving relationships between the angle readers and wavelength, for a two prism fixed position spectroscope head. Because both the collimator and viewer can be rotated around the fixed two prism spectroscope head freely, I had to derive the dispersion as a function of the angle readers for the fixed two prism case geometrically. Using similar reasoning, the derivation can be extended to a n-prism case. Here are the design plans for the Phasmatron spectroscope. The mathematical symbols used are literal names.

(Function/data graphs were done with Claris CAD and Maple and geometrical schematics with EucliDraw)

The Double Amici Prism Hand-held Spectroscope:

Operational diagram for the hand-held spectroscope.

A Toy Spectroscope!

Operational diagram for the toy spectroscope.

(Function/data graphs were done with Maple and geometrical schematics with EucliDraw)

Spectrum Photographs:

The black and white photographs were taken with an Exacta Varex 35 mm reflex camera loaded with Agfapan 100 Panchromatic film. Panchromatic film was used because its response to the various spectrum wavelengths is much more uniform than the response of color film. Shutter speed varied between 1-10 seconds, depending on the luminosity of the source.

The color spectra were taken through the three spectroscopes with a Nikon CoolPix digital camera.

In all cases I used the Inverse Eyepiece Projection method, i.e. I had both the spectroscope eyepiece on and the camera lens.

All spectrum photos were produced using either a suitable High Intensity Discharge lamp or a homemade DC arc device.

Where the whole spectrum is visible, the photos were taken through the hand-held spectroscope. Where parts of the spectrum are visible, the photographs were taken with the Phasmatron Spectroscope.

All spectra are non-linear with respect to wavelength, as they were produced by crystal prisms and not by a grating. For actual line wavelength references, consult NIST.

WARNING: Before you attempt to experiment with DC arcs and High Intensity Discharge lamps, please read my Copyright & Disclaimer.

Amateur Spectroscopy in Astronomy:

Note that all of the above apply for lab spectroscopy only. If you are an amateur astronomy observer, you may need additional equipment and designs to aid in analyzing celestial spectra. Maurice Gavin's Home Page and Robin Leadbeater's Spectroscopy Page contain extensive info on this subject.

Lamp Information Sites:

I highly recommend two other excellent sites on lamps, that of Maxime F. Gendre and that of Donald Klipstein. I consider these two sites to be very authoritative sources on lamp history, internal bulb mechanics, construction, troubleshooting and many theoretical aspects of various lamps. If you have any questions whatsoever about any lamp, chances are the answers will be on these two sites.

Home Copyright Music Astronomy Mathematics Programming Spectroscopy Optics Paintings Writing Links About Donate Map

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