# Why is green so much more expensive than red laser?



## LA OZ (Apr 3, 2007)

I am relatively new to laser pointer so these questions may seem laughable but be nice.

So why is green more expensive than red?
What is a good laser for everyday use in the room as pointer?
What else can you do with laser pointer?


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## ajohnson (Apr 3, 2007)

Well, in a nutshell, a red laser pointer is a bare diode, a pretty cheap component. A green (or blue or yellow) pointer has to use crystals (expensice, and sometimes more than one) and an IR diode (cheap) to convert the IR to the frequency you want.


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## LA OZ (Apr 3, 2007)

ah, that explains it. Are those green laser from Dealextreme.com good?


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## SenKat (Apr 3, 2007)

So far - any up to the 50mw range has proven to be amost dead on accurate in terms of output power - AND IR filtering. The 100mw and up - I think Psuedo reviewed one - and it was not fitered as good...others have reported great filtering...so I think it may be a crap shoot as far as how good a unit you get at the higher power levels...no personal experience though...


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## Ashton (Apr 3, 2007)

one point not covered - one of hte major reasons green is expensive and red is not is supply and demand - Red is used in all major optical drives for computers, CD players, DVD players, etc, so there was a massive need so they created a cheeper manufacturing process (you can acctually canibalize a DVD-burner to build a fairly high-powered handheld laser!). Likewise, when/if BluRay becomes a standard feature in the marketplace, the price on blue (purple) diodes will fall like a rock. (while many blue lasers rely on the same crystals mentioned above, blueray has a way to create a bare, blue, diode, just like the reds, but right now it's very expensive because the demand is so low)

However, green has no commercial value outside of laser shows and hobiests.

Also, re: dealextreme, Pusdo's review also mentioned that he carried the laser around for ~1 week, with light use and no major jaring, and it was already out of alignment or damaged. I, for one, am waiting on further reviews befpre taking the plunge. However, that aside, is the 200mw for $120 puts out anywhere near the rated ammount of laserlight (even if it's 150mw) it's a steal!


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## LA OZ (Apr 3, 2007)

I have noticed my cheapo red laser pointer shows pixelation. I gather that is due to the crystal.

Is this true? I can find a dead CD driver and mod it to the Elly body?


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## The_LED_Museum (Apr 3, 2007)

All lasers will show this "pixellation". Red lasers do not have any crystals; they have a laser diode and a collimating lens - nothing more.


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## SenKat (Apr 3, 2007)

The pixelation is due to either the lense, or the quality of the diode - but there is no crystal inside red pointers. You CAN do the Elly mod - detailed guidelines are available in another thread...You have to use a DVD-Burner to get any kind of results - the CD rom's use low power red and IR...depends on what you are looking for....

(DOH ! - beat me to the punch !)


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## LiteTheWay (Apr 3, 2007)

LA OZ - get a EnVee from Lucent Optics (Lucentoptics.com). Great value and great laser and uses AA batteries.


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## LA OZ (Apr 3, 2007)

Awman, that is like $265 upward. I like that fact that it uses AA batteries. I really Envee those that could afford it .

I just watched that green laser burnt a whole through the balloon. That is so dangerous. This is starwar stuff. It got me a little excited. I am afraid it going to burnt my pocket soon.


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## hank (Apr 3, 2007)

The "pixelation" is because a laser is monochromatic -- it's exactly one wavelength, all the photons are at the exact same wavelength --- so when they reflect back to you off something that is at all rough (at the scale of the wavelength) some of the photons will be exactly out of phase and you'll see a little dark spot.
http://en.wikipedia.org/wiki/Speckle_pattern


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## LA OZ (Apr 3, 2007)

hank said:


> The "pixelation" is because a laser is monochromatic -- it's exactly one wavelength, all the photons are at the exact same wavelength --- so when they reflect back to you off something that is at all rough (at the scale of the wavelength) some of the photons will be exactly out of phase and you'll see a little dark spot.
> http://en.wikipedia.org/wiki/Speckle_pattern



Great explanation there.

So the crytal is required to change the wavelength to a green spectrum as for the green laser?


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## LiteTheWay (Apr 4, 2007)

yeh LA OZ. I got a 100mW EnVee and really have not regretted it. 

You can also look up the MajorGeeks website for details on green vs red lasers - they have diagrams with cross-sections etc.


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## 2xTrinity (Apr 4, 2007)

I have a DX 10mW laser and it's awesome -- bright enough for pointing out to stars, and the reflected spot is visible at great distance for outdoor pointing. These are a little bit over $20, or you can go for 30mW for $30 from DX. Either way, those are great prices for what you get IMO. For indoor pointing, a 5mW is the most you should need. For the same amount of power, green will appear about 4 times as bright as a red laser. Also, the green light is reflected better off of moisture and particles in the air, so even comparing between lasers with simialr apparent brightness, the green will have a more prominent visible "beam" in the air. 



> So the crytal is required to change the wavelength to a green spectrum as for the green laser?


The green lasers use an IR diode of 808nm. That is used to pump a crystal that re-emits IR at a longer wavelength, 1064nm. That is then pumped through another crystal that doubles the frequency (halves the wavelength) to 532nm green. This produces an interesting phenomenon where the brightness of the green is dependent on the temperature -- as the crystals must be "warmed up" to be efficient. With my DX lasers, they start out dim, but after a few seconds of constant on-time get a lot brighter.


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## LA OZ (Apr 4, 2007)

hmm the DX lasers look tempting for its prices. I heard the quality control matches the asking price. I don't think I can pop a balloon with 50mW laser.


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## bfg9000 (Apr 4, 2007)

Green is a lot easier to knock out of alignment because four things need to be lined up perfectly instead of two, but does appear a lot brighter than the same wattage red because our eyes are more sensitive to green.

Then there's also yellow laser...


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## roadie (Apr 4, 2007)

did u know ... BLUE is more more expensive ?


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## LA OZ (Apr 4, 2007)

Bluray DVD will probably bring the cost of blue down.


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## brighter (Apr 4, 2007)

LA OZ said:


> hmm the DX lasers look tempting for its prices. I heard the quality control matches the asking price. I don't think I can pop a balloon with 50mW laser.


 
Oh You can, and light matches from 1foot too! I'm amazed on burning power from DX 50mw and it is one reason for that: the beam is only 0.5mm in diameter when exits the unit! Don't understand this as advertisement for buying but a simple fact, and opposite of that this 50mw unit has poor IR filtering, 2-2.5mrad beam divergence (bad) and lack of power when batteries are slightly used. And You must protect it from dust because it enters the unit easily and can spoil the beam and it's hard to clean the lens safe.


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## LA OZ (Apr 6, 2007)

Look like I have to wait till some quality laser come out with reasonable price.


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## Ashton (Apr 6, 2007)

> Look like I have to wait till some quality laser come out with reasonable price.



Or be willing to cut it open and repair it when/if it gets damaged. I'm probably gonna bite on the 200mw DX if it's even 150mw of acctual green laserlight. (b ut then I'm insane, I'm building lasers from scratch (Well diodes and components) and then playing with them without goggles... (NOT RECCOMENDED!!!) so you might not be as crazy)


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## sejvaar (Apr 10, 2007)

Has nobody considered the Empire vs Rebel Alliance factor? The Empire clearly has a larger manufacturing infrastructure allowing a lower retail price for the end user.


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