ZnSe Lenses – ‘VTE’ And ‘BYS’ Series

IntroductionBystronic Lens
Some laser systems are designed to suit high gas pressure lenses of specific edge thicknesses and
38mm (1.5″) diameter. Examples include Trumpf systems using lenses with 7.4mm ET, and newer
Bystronic systems using lenses with 9.0mm ET. (Many Bystronic systems use lenses with 6mm ET
… see data section 4.10, ’15HGP’ series lenses).
Raw material properties
Only lasergrade ZnSe is used in the fabrication of ULO Optics VTE series lenses. See section
M1.0 for detailed optical and mechanical properties of ZnSe.
VTE lenses
The VTE series of lenses are high gas pressure meniscus type, designed to be a direct replacement
for lenses used in Trumpf laser systems. Users of these laser systems have, in the past, been presented
with an array of choices of lenses of a variety of edge thicknesses and small, but significant, variations
in focal length and working distance.
ULO Optics have carefully designed the VTE range to be optically exact replacements for the
lenses supplied by the OEM system builder.
The key features of the lenses which allow immediate replacement are:
* Exact replication of edge thickness.
* Exact replication of flange focal distance.
* Exact replication of centration specifications.
* Absorption better than OEM specifications.

During the lens design programme, ULO Optics carefully ensured that the residual spherical
aberration was minimized.
BYS lenses
In a similar way to ‘VTE’ lenses described above, Umicore Laser Optics have designed a range of lenses
with 9.0mm ET, offering high quality options for the laser user. These lenses are designated ’15BYS’ series.
Coatings
VTE and BYS lenses are manufactured and coated in large batch quantities and the economies of
volume production are passed on to the customer.
The highest possible quality of anti-reflection coating is ensured by matching coating plant
conditions to lens thickness (and mass). The resulting coatings exhibit extremely low absorption
levels, tested by Umicore Laser Optics to ensure conformance with specifications.
The coatings on VTE lenses are masked to 33mm diameter.
The coatings on BYS lenses are masked to 31.5mm diameter.
Special note re: coatings
The ULO Optics coatings do not absorb water vapour, and retain low absorption characteristics
even after the lens is unpacked.

Bystronic lens range

Notes

(4.30A) The stated abs% value for VTE lenses is guaranteed. The typical measured values are
0.17% – 0.20%.
(4.30B) The stated abs% value for BYS lenses is guaranteed. The typical measured values are
0.18% to 0.22%.
(4.30C) The stated centration values are guaranteed. Typical measured values are 1′ to 3′ arc.