There are many things in nature, friend Horatio,
That our sages never dreamed of.
Shakespeare. Hamlet (after reading this article).
Is the title of the article worthy of a madman? Right. But the fact is that the results of the experiment are also worthy of the fantasy of a madman. And the title is quite consistent with the content of the article. In addition, the experiments were done on New Year's Eve, which is almost the same as on Christmas Eve. So, if you started reading the article while standing, then it is better to sit down, and if you are sitting, then hold on tightly to the chair. The results will be stunning. You probably won't believe them. Well. You just have to check them. Testing is always easier than doing an experiment for the first time.
Laser beam path in a prism
It all started more or less usually. The author of the article passed a laser beam through a prism …
We all know that the trail of a light beam in the air is invisible. If we do not see the light source and / or the object illuminated by it, then only by dancing in the air luminous dust particles or fog particles can we detect the presence of the passage of a ray of light. The case is completely different in the case of glass. The trace of a laser beam passing through a completely transparent glass prism is clearly visible (photo 1). Moreover, not only the "trajectory" (straight line segment) of the ray is visible, but also its reflection in the prism faces.
Promotional video:
Photo 1. The upper thick line inside the prism - it is a luminous trace of a laser beam passing through the ends of the prism. Lower - this is a reflection of this trace in the lower edge. It can be seen that the ends of the prism glow quite brightly.
What's the matter here? After all, there are no dust particles or fog particles inside the glass?
Particles of fog (particles of water), with their sufficient size and concentration in the air, reflect light well. Therefore, we see fog and clouds. But at night, as a rule, we see neither fog nor clouds. Apparently, the point here is not only in the size of the water particles and their concentration, but also in the strength of the light. Therefore, we do not see ordinary rays of light passing through the prism inside the prism. We can see the laser beams, and so well that we see nothing behind the trajectory of the light beam, it does not shine through.
In the thickest fog, we can still see our own hand if it is close enough to our eyes. The laser beam trajectory (tl) inside the prism has a thickness of about 1 millimeter. But this thickness is already enough to see nothing behind this ray. Looking at the TL, it is difficult to imagine that a laser beam, breaking through such a "fog", can pass many centimeters or even meters in the glass.
Why do we see tll? Apparently, for the reason that some of the components of the glass particles, like fog particles, reflect part of the laser light. These particles are located very densely, but, on the other hand, we do not notice the weakening of the laser beam due to this process.
One could try to measure the power of light emitted by a section of tll in order to predict how far in the glass the laser beam can travel before the beam is attenuated by half. But it would be much more interesting to know the size of the particles that form the "fog" in the glass and what they are made of.
Laser beam trace in a glass plate
There is a small narrow table with a glass top in the hallway of my present apartment. Its width is 48 cm, glass thickness is 8 mm. The glass is transparent, colorless. The edges of this glass are so well finished that it is impossible to cut and appear to be quite smooth. But, of course, they are not polished or polished to have optical qualities. They don't appear transparent.
But it turned out that this is not too much of a hindrance for the laser beam. The laser beam passes through these edges and, with an appropriate initial direction, can move further in the glass without going out. Apparently there is a light guide effect.
It was here, in this tabletop, that a surprise was hidden, an incredible light effect, which is much more incredible than the trajectory of a laser beam in a prism.
We all know the decomposition of light by a prism into color components. Newton allegedly made sure that it was impossible to obtain additional decomposition of these color components. Green light stays green and yellow light remains yellow. Therefore, it struck me that the initial trace of the trajectory of the green laser beam in the glass was clearly not green. Moreover, it was followed by a green area, and then again not green. This fact had to be documented.
The author had to attach the laser so as to free his hands for photographing. But this particular effect was no longer obtained. But the effect was no less amazing.
Photo 2. In the photo above, approximately in the center of the image, you see a ray going from right to left and which then seems to disappear, entering a brighter strip of green color. In the picture, it looks like a cord with multi-colored strands. If you enlarge the photo a little, you will notice that one of the "strands" is brown. Below (photo 3) with a longer exposure shows the same beam. It will be easier for you to see it again with some magnification. One of the "strands" of this ray will appear yellow to you.
Photo 3. To the left at the top, a narrow beam (framed by green edges) departs through the entire photo, which can be called a "zebra", but not black and white, but white and yellow. This ray, in theory, should also be green, and of course, the same color, and not mimicking a zebra. Part of the wooden slat is visible at the top right. It covers the bright point of entry of the laser beam into the glass plate. In photo 2, due to the low exposure, this rail is practically invisible (it seems absolutely black. Only the dark green edge is visible).
Unfortunately, the camera sees something quite different from what the eye sees.
In photos 2 and 3 80% of the area of the photos on the left is occupied by glass (the tabletop of the "glass" table). Coming from the center of the bottom edge of photo 2, what looks like a piece of thick rope is actually the edge of the glass. In photo 3, in the same place is something that looks more like a rough wooden strip - in fact, it is the same edge of the glass. The piece of "wooden slab" with dark green edges in the upper right corner in photo 3 is part of a wooden batten. It is located here in order to close the bright point of entry of the laser beam into the glass from the lens. The same object is in photo 2 in approximately the same place and for the same purpose, but it is absolutely invisible in photo 2.
What we should be interested in in both shots is a narrow light beam that goes in the middle of the shot from right to left from the meeting point of the edge of the glass and the rail.
Please note: the beginning of this ray in both shots looks like alternating parallelograms, or, if you prefer, two multi-colored strands twisted together. In photo 2 they look like green and brown, in photo 3 they look like yellow and white. In terms of color, image 2 is more consistent with reality. The edges of these parallelograms intersect the beam at approximately an angle of 45 degrees.
From image 2, we can say that this ray looks like a rope twisted from yellow and white strands. But this is only when you look at the beam from one side of its entrance to the glass. On the other hand, this ray looks exactly the same, but you can already understand that these are not twisted strands. Where there are parallelogram joints on one side, parallelogram midpoints are located on the other side and vice versa. That is, on the left and on the right, there is a shift of half a parallelogram. From above, the beam seems to be monochromatic, as if gray-brown. To the eye, the yellow parallelograms appear more likely brown, but clearly not green.
Already here we can note the differences from the theory: green has ceased to be green. But if at all one can expect a change in the color of the beam, then only a change in color going across the beam, as is the case with the decomposition of white light in a prism. What kind of “ray” can we talk about when the color change goes along the ray? It would seem that this in nature simply cannot be. But here you see such a miracle Yudo in the photo. Again, one could imagine that two bundles twisted into a kind of string, but the light rays cannot bend and wrap around anything. But even that is not here. Alternating color parallelograms are visible on both sides of the beam. Please tell me how a ray can periodically change its color along the ray, if you do not assume behind it a background consisting of stripes changing in color? It just can't bethis is even impossible to imagine. This can only be drawn. But we see a photograph.
The experiment is easily repeatable (at least on this glass). If someone has difficulty in repeating the experiment, come to me, we will repeat everything together.
Changing the angle of entry of the beam into the edge of the glass (in a plane parallel to the plane of the glass) practically does not change anything. When the point of entry of the ray is close to the upper plane of the glass, the ray seems to be pressed against it from the inside, then it breaks, goes deep into the glass and then goes on, gradually becoming less and less bright. From below and from above, the beam after the break is accompanied by bright green strands of light, as if pressing against the surface of the glass. Neither the beam itself nor these strands come out outside.
A red laser was also tested. In the same way, a ray appears in the glass, consisting of parallelograms of alternating brightness. But whether there is a change in color, the author was unable to understand. Lasers with a power of about 50 milliwatts were used.
The author at this stage cannot explain the results of this experiment.
Interaction of a laser beam with transparent materials
When this article was already written, the author, in his spare moments, began to test all the transparent materials at hand. With glass, the results were easily repeated, everywhere it was possible to see a trace of the ray trajectory inside the glass, resembling a red-brown color.
The author then tested a piece of plexiglass originally from China. He showed a trace similar to a trace in a prism (photo 1). A surprise, which the author would have considered natural a couple of days ago, awaited him with a piece of plexiglass pipe (diameter 80 mm, length 126 mm, wall thickness 3 mm). In this wall, the ray trajectory is completely invisible. The author met this result with some satisfaction, since a couple of days ago he believed that the trace of a laser beam in a transparent substance is invisible. The surprise, already real, was different: the laser beam did not leave this wall. A bright entrance point was clearly visible, both ends of the pipe glowed quite brightly, a dark arc of the shadow from the pipe wall was visible on the wall, but the beam did not come out of the piece of pipe. The author even tried to look inside the pipe wall from the end: he saw a very bright, downright blinding arc - but not a point.
The author began to look for other plexus items at hand. A ruler was found from the track (length 33 cm, thickness 5 mm, the edges of the ruler are beveled and have a thickness of about 0.5 mm). This ruler was used in the days when drawing boards still existed. In this line, the initial piece of the trajectory of the laser beam was clearly visible, but gradually it became more and more indistinct, and the beam did not come out of it either.
Let us remind the reader that the experiments described began with a glass tabletop 48 cm wide. Although the ray trail inside it is reddish-brown, the ray comes out of it and has the same green color as at the entrance to it.
Thus, there are completely different transparent materials. In some of them, the green laser beam is not visible, in some others it is visible and has a normal green color, in glass the laser beam trace may turn out to be red-brown or even in the form of a straight line consisting of red-brown parallelograms of alternating brightness. The laser beam can pass through, but it may not leave the material at all, turning inside the material in a line whose brightness decreases towards the edges.
Johann Kern, Stuttgart