591nm Laser Pointer

Im quiet happy that I got a yellow lazer for a price so low (was about 160€ in sale at that time). It also works with the standard 1,5V AAA batteries. After some usage I was a bit suprised when the laser started to be weak green for some seconds bevore switching to yellow. Somewhat like a preheat phase. So I did some recherche on the net. Turned out 591nm are hard to achive an rather unsatable because a minor emission of a infrared diode is used. The main emission, normally used for green lasers, is mostly filtere away. When the battery is not fully charged it won't be enought do double the frequency. What reamins is green. If you just want to have a rare laser color and can deal with this issue than it's a good product especially when on sale. If not a better (and higher priced) laser is presumably better for you.