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  1. Benm

    If you buy a laser via paypal from a private-party in China or Japan or Russia, will paypal refund you if you never get the item?

    You can not dispute a transaction that you sent as a 'gift' though. If a vendor asks you to do that just don't go for it, they may not even take the effort to send you some sand in a tube as there is nothing required to be delivered if you send money a a gift.
  2. Benm

    USB Oscilloscope

    Even without the hack those scopes can be work their money, and i'd definitely get one of them or an analog scope instead of something that is only readable by USB. Apart from taking less bench space compared to CRT scopes they also have nice features like single shot capture which can be really...
  3. Benm

    If you buy a laser via paypal from a private-party in China or Japan or Russia, will paypal refund you if you never get the item?

    If they ask you to send the money as a gift, you can't count on any chance of a refund. If the goal is to bypass customs the vendor may label it as a flashlight or just 'electronic component' or whatever they see fit, and you have buyer protection to some degree: if you open a dispute it's up...
  4. Benm

    Cheap "Scanners"

    At least try with proven software so you can see if you hardware is actually working well. The hardware part of it doesn't have to be that complex - you can use opamps to translate the output of a multi-channel soundcard to ILDA levels for both position and brightness control with compliant...
  5. Benm

    Who needs Tetris Effect when we've got this? (aka Tetris with lasers)

    I guess that sort of works, but the projection is pretty far from ideal. Have you calibrated this projector to an ILDA test pattern at all?
  6. Benm

    Diode pump a ruby laser?

    I'm not... the idea is interesting though: could it be possible to pump a ruby rod like that with diode lasers if you go to the extreme, like surrounding the rod with hundreds of diodes from all sides and along the entire length as to get it evenly lit, and fire them in pulse mode just to get...
  7. Benm

    5000MW 650nm burning laser from Widelasers.com

    Yeah, these things will probably burn holes in aircraft from 20 miles away, $19.98 each in two easy 9.99 payments without any interest... or was that just some tell sell block playing in the background? :D
  8. Benm

    Cheap "Scanners"

    This $40 one is only 15k at 15 degrees, so it's a very slow scanner indeed! It is -very- cheap though if it's the real deal, and if you just want to play with it for a bit i think it would make a decent kit to test the waters a bit. There seem to be NO adjustment pots on the driver board for...
  9. Benm

    Diode pump a ruby laser?

    But that rod is not lasing there. It does produce a red dot, but i'm sure it's not monochromatic, it's just fluorescing. This is perhaps similar to a laser diode running below it's lasing threshold current: in produces light like an LED or something similar, but not monochromatic or...
  10. Benm

    5000MW 650nm burning laser from Widelasers.com

    That seems a lot more reasonable indeed. The 200 mW-ish mark for 650 nm diodes is reasonable, these are just dvd writer diodes, with actual power depending on drive current and lens quality, but generally that range is possible with a very cheap setup. If you were to buy an actual 5 watt laser...
  11. Benm

    Appropriate conditions for looking at laser light without glasses?

    When looking at a dot the key issue is that the surface is actually matte. If it is, the dot from a 3 watt 445 laser is no more intense than that of a 445 nm LED shining around a full 180 degrees, and would be safe to look at at armslength. That said, few surfaces are actually that matte...
  12. Benm

    SOLD: Multiline Orange HeNe

    I hope you'll find collector to buy this laser and perhaps have it on display once in while, since it's a complete working system. Given it's 1993 vintage it could be sort of and end-of-era item which could make it valuable to the right buyer, despite having nearly no practical application...
  13. Benm

    This is for the machinists members and others that may be interested.

    Those cubes inside cubes inside more cubes are amazing. Machining those contraptions from a single piece of stock really is machining skill. They're also great conversation pieces as people often wonder how they got one inserted into the other, while that was never the case, and it's...
  14. Benm

    Cheap DIY Heat Sink for Ophir 20C

    Nice heatsinking upgrade :) I suppose you painted them black just for aesthetical purposes though right? A paint can be black in the visible spectrum, but what's important here is the emissivity in the far infrafred. I'm not sure about this specific product (i guess it's the heat resistant...
  15. Benm

    SOLD: Multiline Orange HeNe

    No real use is the problem with these things - they're great lasers but practical application is nearly zero unless someone wanted those other HeNe spectral lines for a specific reason (not that i can think of one). Upside it's that you got a complete working system with power supply there, so...
  16. Benm

    This is for the machinists members and others that may be interested.

    Wow, that seems to be a lot of work to make a cube. Then again i don't get why you would start with a short piece of round stock to make a cube like that. If the stock had been longer the cube could have been much bigger (less material wasted). Also it seems somewhat crazy to start with round...
  17. Benm

    Laser microphone help

    Using a carrier beam may be good to isolate your signal from background noise, especially when doing this over a large distance. Basically this will help you isolate light reflections from other interfering light sources in the beampath, so not a bad idea. Where it goes wrong is in your...
  18. Benm

    Krakatoa eruption

    Having a tsunami early warning system isn't really the problem, they just did not think it was required to install it at this location as something like this has not happened before in recent history. If it had been in place it would have alerted since most such systems simply work with buoys in...
  19. Benm

    Krakatoa eruption

    The island you see here is 'anak krakatoa', which translates to 'the child of krakatoa' - essentially it's an island that formed after the original much larger krakatoa volcano exploded in 1883, one of the biggest volcanic events in recorded history. This whole region is pretty active...
  20. Benm

    Merry Christmas and all who celebrate ..

    Marry Christmas to you all from the netherlands too!




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