'591nm' Yellow Laser Review

TLDR: yellow , tinkerlasers

So I opted to search for a laser with my favorite color. After searching the web I found about a site called Tinker Lasers. Now from their site you would think it's too good to be true since they seem to have every such a good selection... and of course it is too good to be true. I should have been heeded all the warning from posts on here and reddit from the site scamming people, but I ordered anyways. Now I did get the laser, and after some warm up it did give me a nice yellow. But the power I measured (using a Thorlabs power meter) was only 0.7mW, while the laser was advertised to have an output of 15mW. Also the laser did not come with the case which was advertised on all the pen lasers on their site, but instead got a case with the text 'Green laser pointer' .


(very long exposure photo of laser with color correction)

I actually contacted them and told them about the case, and they said they would send one out the very next day, but it has been a few days now and even after emailing them again, still nothing. This seems to be a key tactic that they use in scamming their customers. I think others may have had a similar experience. Anyways enough about the company, it was a risk and I will never order from them again.

SO about the laser. Being that the output power was pathetically low, I decided to break it open to see what was inside. These 591nm lasers, or what are really 594nm lasers, use sum frequency generation to produce 594nm light from a 1064nm and 1342nm. These two infrared wavelengths are obtained from an Nd:YVO4 crystal pumped with 808nm light (using the correct reflective cavity coatings to select said lines) and then sent to a KPT crystal to get summed. Opening up you can see two, what I believe to be, Nd:YVO4 crystal glued next to each other and then a subsequent frequency doubler. Also for reference I included a picture of the classic 532 DPSS crystals which just use a single Nd:YAG and KPT.

594nm DPSS crystals:


532nm DPSS crystals (smaller one is Nd:YAG and larger one is KPT):


I assume the power was low because of a few reasons:
1) misaligned to the cavity
2) multimode 808nm with low power actually doing the pumping
3) the two Nd:YVO4 crystals are not correctly phase matched.

At the end I ended up reattaching the crystals to another 808nm laser which I aligned carefully using a two axis stage (this is very sensitive), but at the end I only got around 5mW of power with over 500mW of seed .

Let me know if I got something wrong or if anyone has advice on how to get more power out of theses crystals. Thanks for reading!

When was the last time your LPM was calibrated? I assume from the 0.7 mW readout that the sensor is a silicon sensor? Silicon sensors drift over time and the reading cannot be readily trusted

That being said, if it really was outputting 15 mW, you should be able to see the beam at night relatively easily. Not such an easy task with 0.7 mW!

hwang21 said:

When was the last time your LPM was calibrated? I assume from the 0.7 mW readout that the sensor is a silicon sensor? Silicon sensors drift over time and the reading cannot be readily trusted

That being said, if it really was outputting 15 mW, you should be able to see the beam at night relatively easily. Not such an easy task with 0.7 mW!

Click to expand...

Not sure about the calibration, but it's not an old device. Even then, any drift should be within an order of magnitude. There was no visible beam in the dark so it is likely well below 15mW.