Use a laser pointer to show that the design of the slideshow has failed. You really can't call it a high power laser pointer anymore...you're more likely to carry a car battery with you as a power source...I don't think any lasers of a convenient size are capable of that, they will last in the military and not in the hands of children . By the way, just place the laser pointer on the lower area of the chainring so that it is flush with the chain so that it points towards the front chainring. If you need to use the laser pointer as a real laser pointer, i.e. for lectures, you can still use a pointer with protection class 2 or if necessary 3A (beam expands here, max 1 mW can penetrate the eye). Then carefully turn the wheel back and forth to see if the laser spot moves evenly along the chain (outer chain plate). If not, turn the chain tensioner slightly to the left or right.
The emission angle of 10mw laser pointer
At the end of the day, green laser pointer sold in Germany are pretty harmless. The Polish/Czech market model situation is completely different and you get some higher performance models. If the guy on the curve next to me does this, the laser pointer disappears very quickly and they don't come back very quickly. More than just misrepresentation. The 10mw laser pointer has almost no divergence angle (the amplification of the laser beam in ideal space). At the maximum possible distance of a football field (~100 m), the beam width at the target is about 7 cm, while at the corners/half positions the beam width is correspondingly smaller. Let's take about 5 cm as a realistic value.
Using a powerful laser pointer placed on the chainring, you can check the alignment of the chain. If this is correct, your rear wheel is also in the correct position. Laser pointers do not guarantee that the housing is parallel to the laser beam. There are additional lasers for adjusting the chain, with a precise plane that guarantees that the laser beam is also parallel to the plane. There is an EU directive prohibiting the placing on the market of laser pointers over 1mW. Ergo transactions (marketing, sales) within the EU are prohibited. It does not matter whether the laser pointer is sold to an individual or to a natural person. In the Bundesrat application, Baden-Württemberg pointed out that in recent years, the 2,000-mw laser pointer has been increasingly used for "blinding attacks" - including against pilots of aircraft and helicopters.