Multi-Element Scanning Lenses


Introductionmulti-element scanning lens
These doublet and triplet scanning lenses are intended to work with the same configuration of scanning
mirrors and beam sizes as the 48TSL  single-element lenses,but are offered at the shorter focal lengths
where better performance is possible.The doublets have focal lengths from 75 to 300mm. Above
300mm the benefits of using a doublet are not great. The triplets are offered in two focal lengths,75 and
100mm.These give diffraction limited performance and even further improvement over the
corresponding doublet.
All the lenses are made from Laser Grade ZnSe, so offer a high power alternative to the MSL/2/15
series doublets which contain a Germanium element.
Each of the lenses comes in a black anodised Aluminium mount and can also be fitted with a ZnSe
protection window as an option.


Material: All elements and protection windows made from Laser Grade ZnSe.
Mountdetails: See Figure 10.51.
Opticalscanfield: +/-20° inXand Y.
Performance: See Table 10.52 and Figure 10.53.
Focallength: Within1%.
Absorption: £ 0.25% per element.
Transmission: > 99.6% per element coated AR/AR for 10.6mm.
Damage threshold: CW3000W/mm at 10.6mm.
See Table10.52 for part numbers, focal lengths,working distances and performance.

multi element scanner lenses

Figure 10.51: Mount Details

scanning lens data table

Table 10.52:Performance data

multi element scanning lens

Figure 10.53: Focused spot size comparison


Notes to Table 10.52 and Figure 10.53
1) Field size is the nominal size with a+/-20°optical scan angle by mirrors.
2) Average focused spot diameter is computed from a 5x 5 array in one field quadrant. The
standard deviation is computed from the same data.
3) The optional ZnSe window is 3mm thick and pushes the image plan distance,WD,about
1.8mm further away.
4) Away from the X and Y scan axes, mirror geometry distortion affects the Fq error.
5) Error bars in Figure 10.53 show the variation in spot size over the field.