| |
|
| |
8.
The best heatsink material is copper, but aluminum
is also a fair heat conductor. |
| |
|
| |
9.
If aluminum is used, the surface should not
be anodized in the region where the laser |
| |
package
makes contact with the heatsink. The aluminum
oxide anodized coating makes an |
| |
effective
thermal insulator. |
| |
|
| |
10.
The diode package should be attached to a heatsink
plate at least several millimeters thick. |
| |
|
| |
11.
Thermal compound, or an indium foil washer can
be used to reduce the thermal impedance |
| |
of
this interface. |
| |
|
| |
12.
Finally, when testing out a heatsink configuration,
it is wise to test the temperature drop |
| |
between
the laser package and the heatsink using a very
small thermocouple touched against |
| |
the
base of the package. The temperature drop during
laser operation should be only 1-2¨¬ C. |
| |
|
| |
|
| |
Open
Laser Package Precautions |
| |
|
| |
|
| |
1.
The C-mount package is a simple open heatsink,
and there is no protection for the delicate
|
| |
laser
chip. The laser chip is very fragile and must
be protected from any mechanical contact. |
| |
The
exposed laser facets (mirror coatings) must
not be contaminated with any foreign material.
|
| |
Facet
contamination can cause immediate and permanent
damage to the laser. You should |
| |
not
blow on the laser, or expose the laser to smoke,
dust, oils, or adhesive fumes. |
| |
|
| |
2.
The laser facets are sensitive to accumulation
of dust. When the laser is operating, dust |
| |
particles
tend to be attracted to the laser facet. As
the dust particles enter the intense optical |
| |
field
at the laser facet, they burn, and the residues
accumulate in the laser facet. Unless the |
| |
laser
is operated in a true "class 100"
clean-room environment, this dust accumulation
will |
| |
occur,
even in a seemingly clean "lab environment".
This kind of contamination does not occur |
| |
very
rapidly, but over several hundred hours of operation
in a normal room environment, tiny |
| |
"specks"
will appear on the laser facet under microscopic
examination. These will gradually |
| |
degrade
the laser prematurely. If the C-mount laser
is to be operated outside of a clean-room for |
| |
more
than short periods. it should be packaged within
a sealed container to prevent this dust |
| |
accumulation.
This does not require a true hermetic sealing
of the laser. An epoxy seal or o-ring |
| |
seal
around the laser assembly is prefectly sufficient.
|
| |
|