Images of the fully shielded luminaire used in Brno (type Victor, made by Thorn). I've used the luminare also for documenting the change of the spectrum of a HPS lamp when starting.

(380k)

These are but details of the luminaire components. I've used a bit damaged fixture I borrowed from the Technology Networks Brno for a couple of days. Due to a slight deformation of the fixture body the glass did not touch perfectly the felt gasket.

Apr 18 18:04, im002119.jpg

(447k) Apr 18 18:05, im002120.jpg

(394k) Apr 18 18:06, im002121.jpg

(371k) Apr 18 18:07, im002122.jpg

(378k) Apr 18 18:11, im002123.jpg

(401k) Apr 18 18:12, im002124.jpg

(423k) Apr 18 18:14, im002125.jpg

(428k) Apr 18 18:15, im002126.jpg

(404k) Apr 18 18:15, im002127.jpg

(342k) Apr 18 18:16, im002128.jpg

(408k) Apr 18 18:18, im002129.jpg

(268k)

The first series of a start of an HPS lamp begins. The initial spectrum is that of a shining mercury vapour. The images have been taken by a HP315 digital camera through spectral glasses (no glass, just a diffraction grating, a foil with both vertical and horizontal grooves, for more see at the bottom).

Apr 18 18:37, im002130.jpg

(149k) Apr 18 18:37, im002131.jpg

(145k)

It became a low-pressure sodium now. The main yellow-orange line (a doublet of course, but too narrow to see it) becomes prominent, the colours are spoiled by the camera.

Apr 18 18:37, im002132.jpg

(132k) Apr 18 18:38, im002133.jpg

(136k) Apr 18 18:38, im002134.jpg

(133k)

The pressure rises and the main yellow-orange sodium line is no line anymore, growing thicker due to ``pressure broadening''.

Apr 18 18:39, im002135.jpg

(115k) Apr 18 18:39, im002136.jpg

(116k) Apr 18 18:39, im002137.jpg

(120k)

An absorption core in the already quite broad main sodium line develops. I suppose that it is produced by a layer of colder sodium vapour along the walls of the corund tube becoming optically thick in spite that it is geometrically very thin.

Apr 18 18:40, im002138.jpg

(113k) Apr 18 18:40, im002139.jpg

(105k) Apr 18 18:42, im002140.jpg

(116k) Apr 18 18:51, im002150.jpg

(116k) Apr 18 18:54, im002151.jpg

(269k)

Another lamp start begins, the first image has been to late to capture the mercury phase. LPS (low-pressure sodium) spectrum is the first one.

Apr 18 20:43, im002153.jpg

(260k) Apr 18 20:44, im002155.jpg

(262k) Apr 18 20:44, im002156.jpg

(247k) Apr 18 20:45, im002158.jpg

(270k) Apr 18 20:47, im002159.jpg

(257k)

This is already a true HPS (high-pressure sodium) spectrum, with the main line being a very broad one, spanning over several fainter lines which remained narrow.

The diffraction glasses I've used are sold for fun, but they are excellent for many purposes. They are a lot easier to use than CD to see all types of spectra around us. They can be ordered from Rainbow Symphony or from Edmund Scientifics (search for ``diffraction'') -- another diffraction foils and literature on using them and on spectra in general can be bought from there as well.

Apr 18 20:47, im002160.jpg