The Phasmatron Spectroscope and its Operational Diagram

Version 2.1 of 9/6/2009-9:33 a.m.

Phasma1.jpg
The Phasmatron Spectroscope. It was built in 1998 and cost $4,500.

Phasma2.jpg
Prism housing dome, showing one SF10 prism and viewer. This area is normally covered with black cloth to eliminate entry of spurious light.

The Phasmatron Spectroscope was designed by this author and built by a professional engineer in 1998. It consists of two SF10 prisms housed in a rectangular dome (seen at the center of the first photo), a telescope viewer (scope on the left on first photo) and a collimator with an adjustable slit (scope on the right on first photo). The entire arrangement is seated against a closed metallic base which houses the mechanism which rotates the viewer and collimator. The rotational mechanism box contains all the necessary gear to adjust the collimator and viewer angles, by rotating the two black knobs seen on the front. The two orange boxes are the angle readers, which read the respective angles measured from the normal of the prism housing dome.


The technical specs of all the optics in the device are:
Viewer 8-24 x D=40mm
Collimator D=50mm
Dispersive Medium 2xSF10 Schott Equilateral Prisms, D=60x60x60mm
Adjustable slit Spindler & Hoyer 0-3mm
Angle Readers 90 from Normal of Prism Housing Dome
dn/d 1.2702*10-5/A (Sodium D Light)
Resolution 0.3866148 A (Sodium D Light)
Resolving Power R 15242.4 (Sodium D Light)
dE/dn 3.9724624 rad (Sodium D Light)
Dispersion dE/d 5.04582*10-5 rad/A (Sodium D Light)
Spectrum Angular Width E 13.42-16.84
Weight
35 kg

For a mathematical derivation of the above, consult article Phasmatron Optical Characteristics

phasmaplan.gif
Operational Optics diagram for the Phasmatron spectroscope.

Here are sections of some spectra photographed through the Phasmatron spectroscope and a Nikon CoolPix digital camera and processed with Photoshop, MW Snap 3 and Iris. The author will be adding more spectra as time allows and make corrections, so make sure you reload this page every time. Please note that this page is optimized for use with Internet Explorer. Navigator does not show the table correctly and links to photos don't work.
Light Type Visible Spectrum Section Spectral Distribution
[1]: Triphosphor fluorescent spectrum section on the area of the mercury yellow lines and the mercury green line at 8x. Compare with spectrum [1.3.4] taken with the smaller amici spectroscope. PhasmaCFL4K1.jpg PhasmaCFL4K1.gif
[2]: Triphosphor fluorescent spectrum section on the area of the Europeum red fluorescence line and mercury yellow lines at 20x. Compare with [1.3.4] taken with the smaller amici spectroscope. PhasmaCFL4K2.jpg PhasmaCFL4K2.gif
[3]: Triphosphor fluorescent spectrum section on the area of the mercury green line at 16x, showing terbium fluorescence around the line. Compare with [1.3.4] taken with the smaller amici spectroscope. PhasmaCFL4K3.jpg PhasmaCFL4K3.gif
[4]: Triphosphor fluorescent spectrum section on the area of the mercury blue-green line at magnification of 16x, showing terbium fluorescence around the line. Compare with [1.3.4]. PhasmaCFL4K4a.jpg PhasmaCFL4K4a.gif
[5]: Triphosphor fluorescent spectrum section on the area of the mercury blue-green line at magnification of 24x. This is the same as [4], enlarged. PhasmaCFL4K4b.jpg PhasmaCFL4K4b.gif
[6]: Triphosphor fluorescent spectrum section of the area of the mercury blue line at magnification of 8x. This is equivalent to a low pressure mercury line at 436nm. PhasmaHg1.jpg PhasmaHg1.gif
[7]: High Pressure Mercury spectrum section of the area of the mercury blue line at magnification of 8x. This is the same area as [6]. Note self-absorption and thermal broadening of the blue Mercury line. PhasmaHg2.jpg PhasmaHg2.gif
[8]: Triphosphor fluorescent spectrum section of the area of the mercury blue line at magnification of 24x. This is again equivalent to a low pressure mercury line at 436nm. PhasmaHg3.jpg PhasmaHg3.gif
[9]: The high pressure blue Mercury line at 24x. This is the same area as [8]. Self-absorption and thermal broadening are now easily visible. Photographs [8] and [9] are pushing the spectroscope to its limits. PhasmaHg4.jpg PhasmaHg4.gif
[10]: Portion of the Solar spectrum between the Hydrogen C=Ha and Sodium D lines. D lines resolve at 8x. PhasmaSolar1.jpg PhasmaSolar1.gif
[11]: Zoom on the Sodium D line, above at 24x. The D1/D2 absorption doublet is clearly visible. PhasmaSolar2.jpg PhasmaSolar2.gif
[12]: Portion of the Solar spectrum around the iron E line, with Magnesium b1/b2/b3 lines visible. PhasmaSolar3.jpg PhasmaSolar3.gif
[13]: Portion of the Solar spectrum around the F=Hb line. PhasmaSolar4.jpg PhasmaSolar4.gif
[14]: Section of the spectrum from a low pressure Sodium discharge at 8x taken while a high pressure Sodium lamp was warming up, and while mercury was still participating in the discharge. PhasmaNa1.jpg PhasmaNa1.gif
[15]: Same as [14], at 24x. The low intensity deep orange lines at (*) on this photo (approximately at the center of the photo) and on [14] are ghosts/artifacts of the Sodium D1/D2 lines. PhasmaNa2.jpg PhasmaNa2.gif
[16]: Portion of the spectrum from a low pressure Sodium discharge. Besides the D1/D2 doublet two more Sodium doublets, a red one to the left and a green one to the right are visible. The (*) lines are ghosts, as in [14]/[15]. PhasmaNa3.jpg PhasmaNa3.gif
[17]: Same as above, but with pressure increasing. The D1/D2 doublet is starting to self-absorb and emit light on the neighborhood of D1/D2 wavelengths (display of "wings"). PhasmaNa4.jpg PhasmaNa4.gif
[18]: Same as above, but with pressure still higher. The D1/D2 doublet has completely reversed itself and self-absorption is now clearly visible. The green Sodium doublet also displays some thermal broadening. PhasmaNa5.jpg PhasmaNa5.gif

For an explanation of why some spectral lines appear curved, click here.
For Color Spectrum photographs taken with a high quality small spectroscope, click here.
For Color Spectrum photographs taken with a toy spectroscope, click here.
To see some of the lamps that produced these spectra, click here.

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