Specifications

Beam Delivery

in industrial environments is to have the beam path from the laser to

the final focusing lens completely sealed, and purged with clean gas.

Purge Gas

Diamond K-series lasers have a purge gas inlet. The recommended

gas is dry nitrogen, which is most conveniently obtained from a

Dewar (nitrogen from cylinders, in addition to being more expensive

than cryogenic nitrogen, is more subject to contamination with oil or

water). It is also possible to use air as long as it meets the following

criteria:

• Filtration 1 micron

• Dew point 10°C below incoming water temperature

• 99.995% oil free

To achieve this quality of air from most standard industrial

compressed air supplies requires the use of a coalescing filter and an

air drier. One suitable arrangement consists of a Balston A912A-DX

coalescing filter followed by a Balston 7601 drier. A Balston 41-071

indicator on the coalescing filter will signal when the element must

be replaced. The use of unfiltered compressed air (which typically

contains water and oil) will almost certainly cause premature failure

of the laser optics.

On industrial systems, the gas supply should be interlocked to

prevent operation unless the purge gas is flowing. A flow switch

rather than a pressure switch should be used as a sensor, since line

blockage after a pressure switch will not generate a fault indication.

Use Teflon, polyethylene or polypropylene tube to deliver the purge

gas. Do not use PVC or similar materials which can outgas.

In order to keep the flow of purge gas to a reasonable level, the beam

delivery system must be sealed. Starting at the laser, a carrier for a

shaft seal or O-ring may be attached to the 1.75-20 threads on the

front bezel of Basic and Performance K-series laser heads. Since this

bezel is isolated from the laser resonator, it may be subjected to

considerable load without affecting the output. On the OEM

K-series models, however, the exit tube is attached to the beam

shaping optics. When attaching a seal to this 1 inch (25.4 mm) tube,

it is important that no loads be transmitted to the tube. A flexible

bellows such as a Gortiflex CT-1 (from A and A Manufacturing) is

the best solution to this problem.

For G-series systems, a combination purge gas inlet and beam tube

seal should be attached to the laser’s output plate.