What does a focus lens do?
Laser cutting and engraving machines use a laser
beam with a diameter around one-quarter of an inch (240 thousandths). In order
to achieve high-quality engraving and precise cutting, the laser beam uses a
system of mirrors and focus lens that redirect the laser.
Laser systems use plano-convex lenses to focus
laser light. Laser light enters a convex lens and begins to converge to a focal
point, upon crossing the focal point, the light then diverges out again.
This focus converts the laser beam into a very
small and precise spot with extremely accurate results for a wide variety of
applications. As the laser beam leaves the focus lens, being positioned in the
ideal focal distance, it starts to make the cut or engrave, as it is showed
below:
The focus tolerance (depth of focus) is the area in
which the beam has the smallest diameter. The larger the lens the longer the
focal tolerance. This is especially important if you want to cut through thick
materials in which case you will need a larger lens. The shorter the lens focal
length, the more quickly it will converge/diverge, the smaller the focal spot will
be and the shorter the depth of focus will be.
As the focal spot gets smaller, sharper details are
seen in the laser image that is processed, producing a brighter and more
detailed image.
Which focus lenses work best on which types of
projects?
What is the best lens for my application?
1.5-inch lens:
·
High resolution engraving.
·
Best for thin
(less than 1/16 inch) materials.
·
Small font or
very fine detail engraving.
·
About 40%
smaller than the 2.0 inch focusing lens.
· About 38.5mm of thickness, for very thin materials.
·
Graphics with
medium detail and resolution.
· About 63.5mm of thickness, for majority of works
·
Used for
longer vertical distance.
·
Used for
cutting thick materials.
· About 101.6mm of thickness, for very thick materials
Important considerations
The lens you need is directly related to your
application. These are some important considerations that will define the lens
you must use:
·
Output of
your laser device (laser beam wattage).
·
Material and
purpose (cutting or engraving).
·
Detail level
of the graphics.
·
Thickness of the material.