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FrozenGate by Avery

Lasence: Yellow laser modules just got cheaper

Encap said:
Guess that you have never seen a motion picture or a laser show projector in operation--no? lol

"The flicker fusion threshold, or flicker fusion rate, is a concept in the psychophysics of vision. It is defined as the frequency at which an intermittent light stimulus appears to be completely steady to the average human observer.

As long as the modulation frequency is kept above the fusion threshold, the perceived intensity can be changed by changing the relative periods of light and darkness. One can prolong the dark periods and thus darken the image; therefore the effective and average brightness are equal. This is known as the Talbot-Plateau law. Like all psychophisical threasholds, the flicker fusion threshold is a statistical rather than an absolute quantity. There is a range of frequencies within which flicker sometimes will be seen and sometimes will not be seen, and the threshold is the frequency at which flicker is detected on 50% of trials.

Different points in the visual system have very different critical flicker fusion rate (CFF) sensitivities; the overall threshold frequency for perception cannot exceed the slowest of these for a given modulation amplitude. Each cell type integrates signals differently. For example, rod photoreceptor cells, which are exquisitely sensitive and capable of single-photon detection, are very sluggish, with time constants in mammals of about 200 ms. Cones, in contrast, while having much lower intensity sensitivity, have much better time resolution than rods do. For both rod- and cone-mediated vision, the fusion frequency increases as a function of illumination intensity, until it reaches a plateau corresponding to the maximal time resolution for each type of vision. The maximal fusion frequency for rod-mediated vision reaches a plateau at about 15 Hz) whereas cones reach a plateau, observable only at very high illumination intensities, of about 60 Hz.

In addition to increasing with average illumination intensity, the fusion frequency also increases with the extent of modulation (the maximal relative decrease in light intensity presented); for each frequency and average illumination, there is a characteristic modulation threshold, below which the flicker cannot be detected, and for each modulation depth and average illumination, there is a characteristic frequency threshold. These values vary with the wavelength of illumination, because of the wavelength dependence of photoreceptor sensitivity, and they vary with the position of the illumination within the retina, because of the concentration of cones in central regions including the fovea and the macula, and the dominance of rods in the peripheral regions of the retina."
From: https://en.wikipedia.org/wiki/Flicker_fusion_threshold

Iphone app flicker tester for those interested in same - "The Flicker Tester app for iPhone from Viso Viso systems, makes it possible for the first time to measure flicker coming from LED light sources and LED video screens."

Click to expand...
Yeah most light bulbs flicker at 60Hz anyways, so if a 50% cycle diode can be driven at say 120Hz (do high frequencies destroy diodes? Sorry just have 0 PWM experience) then it would probably appear as a steady beam
 





Sowee7 said:
i had just discovered something, i decided to tear down my 561nm and 575nm laser modules and i found that they are using the same pump diode, i can use the smaller lasence pump diode to pump the 575nm crystal edit: i can use an 808nm pump diode to pump the 575nm and 561nm crystals
Click to expand...
Is that 808nm pump diode pulsed or can you achieve a cw yellow laser this way?
 
LiveRay said:
Is that 808nm pump diode pulsed or can you achieve a cw yellow laser this
Click to expand...
I am using a cw 808nm diode to pump it, it doesn't even have to be that strong! You can use a 250-300mw pump diode and get 2mw of 565nm output
 
Oh cool, that sounds really promising. 2mW is more than enough for a laser close to 555nm.
 
LiveRay said:
Oh cool, that sounds really promising. 2mW is more than enough for a laser close to 555nm.
Click to expand...
I have a 25mw 555nm laser, it is Also using an 808nm diode to pump it, it uses yb:ycob as the crystal
 
LiveRay said:
Did you get the crystal from that alibaba link? Looks like they sell 555nm too
Click to expand...
They don't sell crystals.
You can buy a module if they have any they can deliver, take it apart to experiment/play with the crystal and different diodes and so on if that is what you are looking to do for whatever reasons.

Much of what they do have listed on Alibaba they can't deliver anyway due to technical and production problems that have been ongoimg for years, in addition to there being little interest in any of it. There is an established large marketplace for other Lasence products that have no probems that they can make money much easier maketing, making, and delivering product. You can ask if they can supply/sell you a couple of sample pieces of whatever you want and see what they say email them and ask : sales@lasence.com
see: https://lasence.en.alibaba.com/prod...5fae7220oBm8cI&filterSimilar=true&filter=null

See more about these low output, low end, low cost "yellow" lasers and problems associated with bothering at all with the product, production and technical problems, and delivery problems in this thread: https://laserpointerforums.com/thre...d-any-power-is-fine-starting-from-1mw.108105/
 
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Encap said:
They don't sell crystals.
You can buy a module if they have any they can deliver, take it apart to experiment/play with the crystal and different diodes and so on if that is what you are looking to do for whatever reasons.

Much of what they do have listed on Alibaba they can't deliver anyway due to technical and production problems that have been ongoimg for years, in addition to there being little interest in any of it. There is an established large marketplace for other Lasence products that have no probems that they can make money much easier maketing, making, and delivering product. You can ask if they can supply/sell you a couple of sample pieces of whatever you want and see what they say email them and ask : sales@lasence.com
see: https://lasence.en.alibaba.com/prod...5fae7220oBm8cI&filterSimilar=true&filter=null

See more about these low output, low end, low cost "yellow" lasers and problems associated with bothering at all with the product, production and technical problems, and delivery problems in this thread: https://laserpointerforums.com/thre...d-any-power-is-fine-starting-from-1mw.108105/
Click to expand...
i took the modules apart to get the crystals
 
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