Techhood "591" nm laser which is really 593.5 nm

Received two lasers sold by Techhood in China listed as 591 nm, but they both measure 593.5 nm instead of what I ordered. The good news is they worked and both produced 30 mw of output power or more. When testing I found a very small amount of power peaking at about 811.3 nm which kept creeping to a longer wavelength as the module warmed I believe must be the pump diode leaking through.

The following isn’t unexpected due to testing without a proper heatsink, but when powered at at 3.65 VDC (3.7 specified max) the two units I received both have unstable output after 30 seconds, reducing output power lower and lower as they warm. A good heat sink should solve the problem, temperature controlled active cooling certainly would.

Not the wavelength specified:

Appears Techhood might be listing all of their yellow lasers as what ever wavelength people might be searching for on ebay looking for hits and selling them all the same 30 mw yellow laser heads. Not a bad deal, I just don’t like expecting and paying for a specific wavelength and getting something different. However, to give the benefit of a doubt Techhood recently remarked to another buyer they don’t have a spectrometer to measure the output wavelength, so it is possible they were sold these as 591 nm. Regardless, the price is LOW for a yellow laser head like this and in my opinion, a good deal.

Above, the modules received from Techhood with 591 nm marked on the bag. Spring soldered to the driver board is negative polarity, the brass body positive.


I’ve confirmed these to be classic 593.5nm as well. They are unstable like we’ve known 593.5’s to be for years, however I haven’t noticed mode hopping with these. As for techhood themselves, they are an ok source for these to get them cheaply. However, despite the fact they delivered on the 555nm and 591nm modules, techhood has lost my future custom over the dealings I had over the 561nm module. It’s worth noting the lime green modules are SFD rather than ordinary SHG/SFG’s. So wavelength variation exists between batches. First 561nm batches were apparently true 560-562nm’s. Newer batches are now the same as the 555/558 listings. I’ve contacted tinkertavern to see if he has any original 561’s left.

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Do you know if Robinson is still running Techhood? Maybe that is why things are as reliable with them now for the specs they claim to be? I still have tht 561 nm here with your name on it.

I have no idea about that. When I was communicating I got the impression I was dealing with the Chinese. As for the 561, I appreciate it. Tinker didn’t get back to me.

I suspect Robinson is his English name for business, not his real name. I think Tinker has learned not to answer questions, he had an expander listed I asked if it was AR coated and if so, the wavelength, he didn’t know if it was coated or not? What??? You can look at it and see. He promised to ask the manufacturer, I emailed him twice over a period of weeks asking if he received the info, crickets.

I know my 573 I bought spectrod at 573.7nm, but it turned out to be under 573nm in the end. The result is obviously a bit more green tinge than I would have expected had it turned up correct. Its more 572nm. I’m still very happy with the colour. But had expected a laser as far away from 570nm as possible because I specifically requested it.

I had asked tinker whether he still has any original 561’s left. He said he would check and get back to me but nothing. Like you say. He’s not the best at communicating back.