IgorT
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Re: 6x Blu-ray SLEDS GB! GET EM WHILE THEY LAST
Very nice.. Altho you should be careful with the Meredith, as the 660nm coating can increase the retroreflections at 405nm (that's why 650nm coatings look blue - they reflect blue).
It depends on the particular coating, and the Meredith doesn't look nearly as blue as some do, but it's hard to say just from looking at it. Some 650nm coatings can seem like an uncoated lens to a 405nm diode, others can have very high reflections in the 405nm range. In that case, the effect is the same as raising the current...
EDIT: I just did a simplified reflection measurement. I have no idea how accurate it is, but it would seem to be on the level of ~7% - that's like an uncoated lens.. Even if i missed something, it can't be that much more. So it doesn't seem to be worse than uncoated lenses in the reflection department. This explains why it increases the power, the good news is, it does so without increasing the strain on the diode! I also tested a 650nm AR coated acrylics, and even tho i couldn't get the entire reflection on the thermopile, it was already over 12%! The total could be twice that or more... That's why they halve the output of a 405nm diode, and at the same time increase the strain on it..
BTW, i made a somewhat shocking realisation recently. I saw a photo of a high power blu ray beam with the Meredith lens. And i saw something eerily familiar in it - the "wings"!
I have 30 405nm AR coated lenses (R<0.5%) here, which i declared useless and considered them a total loss, because they have those exact same wings! I've been sitting on them all summer! I was so obsessed with trying to achieve a perfect beam and spot (like the AixiZ acrylic makes, only thinner), that i completelly overlooked the fact, that the Meredith does the same thing! :-[
They increase the power by around 16.5-19.5%, depending on which plastic lens you compare them to (the plastic lenses vary), and the specific wavelength of the diode (lower wavelengths are increased more, due to the sharp cut-off of acrylics at ~400nm) and reduce reflections to under 0.5%. That means increased power at reduced strain... For the diode, it's almost like setting the current lower, except that you get more power!
I considered them useless, but maybe i was too worried? Would you like to test one? I'm sending some to Dave too.
Altho i do not intend to use them, as the v3 are much better... Just for experimentation.. Or as a "novelty item" - the first hobby custom lens ever.. :
Very nice.. Altho you should be careful with the Meredith, as the 660nm coating can increase the retroreflections at 405nm (that's why 650nm coatings look blue - they reflect blue).
It depends on the particular coating, and the Meredith doesn't look nearly as blue as some do, but it's hard to say just from looking at it. Some 650nm coatings can seem like an uncoated lens to a 405nm diode, others can have very high reflections in the 405nm range. In that case, the effect is the same as raising the current...
EDIT: I just did a simplified reflection measurement. I have no idea how accurate it is, but it would seem to be on the level of ~7% - that's like an uncoated lens.. Even if i missed something, it can't be that much more. So it doesn't seem to be worse than uncoated lenses in the reflection department. This explains why it increases the power, the good news is, it does so without increasing the strain on the diode! I also tested a 650nm AR coated acrylics, and even tho i couldn't get the entire reflection on the thermopile, it was already over 12%! The total could be twice that or more... That's why they halve the output of a 405nm diode, and at the same time increase the strain on it..
BTW, i made a somewhat shocking realisation recently. I saw a photo of a high power blu ray beam with the Meredith lens. And i saw something eerily familiar in it - the "wings"!
I have 30 405nm AR coated lenses (R<0.5%) here, which i declared useless and considered them a total loss, because they have those exact same wings! I've been sitting on them all summer! I was so obsessed with trying to achieve a perfect beam and spot (like the AixiZ acrylic makes, only thinner), that i completelly overlooked the fact, that the Meredith does the same thing! :-[
They increase the power by around 16.5-19.5%, depending on which plastic lens you compare them to (the plastic lenses vary), and the specific wavelength of the diode (lower wavelengths are increased more, due to the sharp cut-off of acrylics at ~400nm) and reduce reflections to under 0.5%. That means increased power at reduced strain... For the diode, it's almost like setting the current lower, except that you get more power!
I considered them useless, but maybe i was too worried? Would you like to test one? I'm sending some to Dave too.
Altho i do not intend to use them, as the v3 are much better... Just for experimentation.. Or as a "novelty item" - the first hobby custom lens ever.. :
