LF Series – Line Focus-Lenses

IntroductionLine-focus lens
The LF series of lenses was first designed to enable production of square holes in cigarette filter tips.
The lenses produce a line focus by means of the introduction of a cylindrical lens element into what
is otherwise a ‘TF’ style 2 element assembly. (See Section 20.1). In one direction, the thickness of
the line, the performance is diffraction-limited; orthogonally, the length of the line is determined by
the cylindrical lens.
All models are based on use with a CO2 laser whose beam has a 2.0 milliradian far-field divergence.
Determination of the line size for other beam parameters requires calculation by ULO Optics. The
lenses are intended for use at 10.6μm wavelength.
Technical specifications
Clear aperture : 25.4mm.
Lens material : Lasergrade ZnSe (3 elements).
Coatings: : All surfaces have low absorption anti-reflection coatings.
Sealing: : The lenses are assembled using indium wire for moderate gas
pressures up to 6 bar.
Cell material: : Aluminium HE30.
Finish: : Black anodised.
Cell size: : M11-type cell (See Fig 26.41)

[Slightly modified version].

Line-Focus Diagram

Associated equipment
The LF lenses have the standard 1.5″ diameter 12TPI thread and so may be used with any of the
following equipment:
FF25 and CFF25 focusing heads (Section 63.0)
WMA water cooling mount (Section 20.3)
GNA gas nozzle (Section 20.6)
ZX10 zoom beamreducer (Section 20.5)
Note that the zoom beam reducer would allow the aspect ratio of the focused line to be changed. As
the incoming beam size is reduced, the line length decreases and the line width increases.

Line Focus table