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I have two laser pointers that I will be setting up some photos with and lining the beams may take up to 20 minutes or so. I searched the forum and found some limited info on a post 4 years ago, but rather than resurrect it, I have some additional questions I would like to ask your help with.
Pointer 1: 445nm M140 2W in copper module w/ 3 element glass lense (DTR's)
58gm tapered/extended copper heat sink (Survival Lasers)
Fixed current 1.8A driver (survival lasers)
C6 aluminum host
powered by 7.4V li-ion (2x 18650s)
I will be mounting it to a tripod to keep its position steady in a room 68°F
Does anyone else have a similar build? This is my first one. Did I do ok?
I can't find a data sheet on this diode and I'm not quite sure how Tj = Ta + P / Rja works :-(
Tj (max temp of diode) = 50°C ??
Ta (ambient temp) = 20°C
P (heat from diode) = Is their data on this or do I need to use an IR thermomenter on the Heat sink?
Rja (thermal conductivity of heat sink) = according to the older post: http://laserpointerforums.com/f44/how-determine-duty-cycle-63807.html
I understand that mass (58gm for me) has little contribution for thermal resistance so do I need to measure the diameters (more than one since it is tapered or take an average) and use some (unknown to me at this moment) equation for thermal conductivity? The thermal conductivity coefficient for copper is 401 W/(m k) at 25°C according to: Thermal Conductivity of some common Materials and Gases
Any help would be appreciated.
My second build is for my nephew and I would like to be able to tell him how long on/off his will be.
Oclaro 250mW 638nm Diode In Copper Module (DTR's)
anodized aluminum heat sink (Survival Laser)
1.2A driver (Survival Laser)
C6 aluminum host
powered by 3.7V (1 x 18650)
I haven't built the second one yet but the parts are on the way. I haven't lit my 445nm pointer for more than 20 sec until I can get more info.
Any help, warnings, suggestions, or praise will be much appreciated,
:thanks:
Pointer 1: 445nm M140 2W in copper module w/ 3 element glass lense (DTR's)
58gm tapered/extended copper heat sink (Survival Lasers)
Fixed current 1.8A driver (survival lasers)
C6 aluminum host
powered by 7.4V li-ion (2x 18650s)
I will be mounting it to a tripod to keep its position steady in a room 68°F
Does anyone else have a similar build? This is my first one. Did I do ok?
I can't find a data sheet on this diode and I'm not quite sure how Tj = Ta + P / Rja works :-(
Tj (max temp of diode) = 50°C ??
Ta (ambient temp) = 20°C
P (heat from diode) = Is their data on this or do I need to use an IR thermomenter on the Heat sink?
Rja (thermal conductivity of heat sink) = according to the older post: http://laserpointerforums.com/f44/how-determine-duty-cycle-63807.html
I understand that mass (58gm for me) has little contribution for thermal resistance so do I need to measure the diameters (more than one since it is tapered or take an average) and use some (unknown to me at this moment) equation for thermal conductivity? The thermal conductivity coefficient for copper is 401 W/(m k) at 25°C according to: Thermal Conductivity of some common Materials and Gases
Any help would be appreciated.
My second build is for my nephew and I would like to be able to tell him how long on/off his will be.
Oclaro 250mW 638nm Diode In Copper Module (DTR's)
anodized aluminum heat sink (Survival Laser)
1.2A driver (Survival Laser)
C6 aluminum host
powered by 3.7V (1 x 18650)
I haven't built the second one yet but the parts are on the way. I haven't lit my 445nm pointer for more than 20 sec until I can get more info.
Any help, warnings, suggestions, or praise will be much appreciated,
:thanks:
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