cylindrical lens pair vs anamorphic prisms?

[catalanjo]

Thanks ...it was me who asked.... I originally had the impression (from fleabay advert) that this card had two switching settings but thanks to your pics I can see that it is just one with inverted relay output terminals for heating or cooling.

With two different settings I was hoping to use just one card for switching TEC (one setting/relay) and switching modulation input (second setting/relay @ higher temp).

However it does show both actual temp and switching temp simultaneously, whereas my half price card only has one display and you have to push a button to check switching temp..... it also has buttons and display on wrong side of board for panel mounting unlike your card. (hence the half price I suppose).

Cheers

[Maltes]

I think you should make a thread about your build, it deserves its own place.


I'd still consider a no TEC solution if you want to overdrive to 1W or so.TEC wastes PSU power needlessly here I think.
If you are worried about damaging your diode than again, get a driver that will cut power to it after its reading exceeds certain temp. Looks like you don't mind spending on parts for your build so I think you wouldn't mind spending a little time and money and try this method instead as well. The termistor for those is tiny, it can fit in a small drilled hole, not like the tube shaped temperature sensor that came with your TEC driver.

[catalanjo]

This decision should depend much more on expected ambient temperatures, than any other factor IMHO.
Cheers

[Maltes]

Hm, please explain this if I am wrong. Doesn't the ability of the peltier to cool properly also depend on the ambient temperatures, because the hot part needs a heatsink and fan, like the diode does directly with my approach?

[catalanjo]

Hm, please explain this if I am wrong. Doesn't the ability of the peltier to cool properly also depend on the ambient temperatures, because the hot part needs a heatsink and fan, like the diode does directly with my approach?

The Peltier can run quite happily at higher temperatures than the LD, which will die very young if operated outside of its temperature range. The hotter the hot side of the peltier, with its corresponding heatsink, the easier it is for this heat sink to dissipate the heat into its surroundings (both with and without fans. (obviously easier with fan.)
Even with thin finned heat sinks and a good fan, the the diode temp is going to be at the least 8 degrees higher temp than ambient. So if diode is to be kept at even 22C to 25C, ambient temps must be between 30C and 32C, or the diode will heat beyond its (long life expectancy) spec range after a while. Place a thermometer near the ceiling of a normal central heated home and you will get a big surprise.

Most people rely much more on the thermal inertia of their heat sinks, rather than their dissipation characteristics, without even realising it, especially in cool countries like UK. If you do "proper" temp testing, (requires considerable patience) eg. what Planters would do, you will find that most projectors, (unless tec cooled) will over heat their diodes if they run for more than about 30 mins. and many much earlier.
Many professionals consider 30 mins a VERY long time for a laser show simply due to the type of gig they usually do.

For king4quarter:

I can only suggest that you "suck it and see" which is the only way to get an understanding of how your cooling system really behaves. I use a minimum of 5 thermometers whenever I am testing a new setup. Any less, and you don't get a good idea of what's really going on. If a multistage cooling system is to be used, (very cold diodes) you will need more than 5 sensors, as heat spread and pumping capabilities will vary considerably between same make and model peltier (especially if they are cheap).

One of the problems with peltier cells, as Planters has already pointed out on a number of occasions, (including in this thread,) is that they are horrendously inefficient. So to follow one peltier by others in series, you would need to double (at the very least), or triple (more likely), the second stage due to the extra heat created within the first stage which is far far greater than that generated by the LD itself.
Another problem is that a non functioning peltier (for whatever motive) is quite a good INSULATOR, despite its apparently conductive construction and all the thermal paste etc. So safety thermostats are absolutely essential to avoid LD injuries or deaths due to peltier (or its driver/PSU) malfunction, they also do not have very long lives!

Having come from a background of ion laser tubes, I find it remarkable how the tubes always outlive any LD's, by a massive margin (>10 times life span), partially due to the fact that tubes run far hotter than ambient so are easier to cool, and also because their design will not allow you to "ignore" their temperature requirements. The idea (held by many) that LD's are cheap enough to replace anyway, is only true if one ignores the hassle and work involved in replacing them, (especially in multi-diode setups). It is all too easy to get seduced by simple cooling systems, especially if they have large thermal inertias (which most have), and as this seems to make the projectors appear more robust, there is a massive tendency to travel this IMHO rather absurd route.

I hope this helps, but I think we have drifted (once again) rather a long way off the thread topic here !

Cheers

[CDBEAM]

So what is the answer to this question? "I'm still not sure if I understand correctly, you mean to overdrive 500mW mitsus to 2W each?"

Hmmm...First...I still am of the opinion that the Oclaro 63193 are a slightly more efficient diode than the P73....AND 2W each ??? HAHAHAHA ????
.
NO !! you may get about 1W each....with adequate heat sink / fan cooling....Now....If you want to deep cool the diode...ala liquid nitrogen....well then....IFIRC....Planters gets upward of 1300mW per LD....But....then you must entomb the LD....and heat the output window to prevent condensation from screwing things up !!
.
Seems like a lot of work !! Doable....but....demanding !! I just cannot believe.....we have been " stuck " on this MM 63193 Red....ALL this time....and nothing new....for what 2+ years....wow !!

[Maltes]

Even with thin finned heat sinks and a good fan, the the diode temp is going to be at the least 8 degrees higher temp than ambient. So if diode is to be kept at even 22C to 25C, ambient temps must be between 30C and 32C, or the diode will heat beyond its (long life expectancy) spec range after a while.

I see. But 30C ambient temp and running it for a while? I rather have a outdoor projector housing which cools itself if I'd need to use lasers in such a setting for so long. Like with video projectors. http://www.audipack.com/products/rid..._eb_g5750.html

That said, I have noticed cheaper 1-2W diode lasers shooting beams in clubs all night long. Maybe their expected life was cut by x10, who knows?

But I get your point.

[catalanjo]

@ "I rather have a outdoor projector housing which cools itself " that requires cooling all the electronics,PSUs,scanners etc. which do not mind 40C in the slightest. This also requires at least 10x cooling capabilities compared to just cooling the 2W diodes.

@ "Maybe their expected life was cut by x10, who knows?" ... the owner,the resident DJ, or the manager,....ask them!

Rule of thumb, ... two short seasons and the projector is considered JUNK!

I occasionally get "given" these types of PJs, when installing decent systems, for "pissed off" new clients.

Cheers

[jors]

So are you happy with those ON-OFF thermostats? I used them in my 1st builds, however temp rise and fall, rise and fall...also the surge current cycle: MAx then 0, Max then 0....
I'm more happy with TEC driver now, which delivers only the necessary amount of current to keep the desired temperature, so not ON-OFF cycle...way more stable temperature and not those ON-OFF peaks to PSU and TEC.
However, along with TEC driver I also go with one of these thermostats to get 3 features: Delay startup, E-stop (disconecting its relay) and overtemp protection.

someone asked about the TEC driver details..
Attachment 51082Attachment 51083Attachment 51084Attachment 51085Attachment 51086Attachment 51087

[catalanjo]

@ "So are you happy with those ON-OFF thermostats?" ... happy = bit of an exaggeration here I think.

I personally usually use D4chills as TEC controller. However as you point out "overtemp protection" is useful as is display of diode temp, and I rarely use same PSU for diodes as for peltiers, the (underdriven) peltiers get the dirty stuff, since they are very cheap,don't last too long anyway, and get replaced on each full service.

@ "so not ON-OFF cycle." ....many TEC controllers are PWM...just faster ON-OFF cycles and the alternative is HEAT in the TEC card although this is not usually in a position where heat is a drastic problem (hot side of primary cooling system).

Cheers