The AN/PAS-13E line is made by Raytheon, not BAe.
There are several lines of AN/PAS-13, each comprising of three different weight, thus leading to a variety of types spotting a similar designation.
The PAS-13 lineage started with TWS I contract seeing Raytheon AN/PAS-13B TWS I (starring BST for LTWS and cooled HgCdTe for the rest).
The TWS II contract went for AN/PAS-13C series by BAe and AN/PAS-13D series by DRS Finmeccanica.
The TWS Bridge contract was again awarded to Raytheon, with the new AN/PAS-13E series.
All PAS-13C, PAS-13D and PAS-13E scopes are with VOx sensor, 320x240 FPA for LTWS, 640x480 FPA for MTWS and HTWS.
As Vic has already said, getting a BAe or Raytheon scope might be hard, but the scopes PAS-13D series are widely available under their commercial designation.
Here the overview..
AN/PAS-13A/B line - made by Raytheon
AN/PAS-13B(V)1 LTWS - W2000 model, 320x240 staring BST, uncooled ferroelectric, NSN 5855-01-464-3150
AN/PAS-13B(V)2 MTWS - 40x16 scanning HgCdTe, 6-stage thermo-electrical cooling, NSN 5855-01-464-3152
AN/PAS-13B(V)3 HTWS - 40x16 scanning HgCdTe, 6-stage thermo-electrical cooling, NSN 5855-01-464-3151
AN/PAS-13C line - made by BAe Systems
AN/PAS-13C(V)1 LTWS - ATS-3200 model, 320x240 VOx, NSN 5855-01-523-7707
AN/PAS-13C(V)2 MTWS - ATS-5000 model, 640x480 VOx, NSN 5855-01-523-7713
AN/PAS-13C(V)3 HTWS - ATS-6000 model, 640x480 VOx, NSN 5855-01-523-7715
AN/PAS-13D line - made by DRS Technologies (Finmeccanica)
AN/PAS-13D(V)1 LTWS - UT-3500 model, 320x240 VOx, NSN 5855-01-540-6522
AN/PAS-13D(V)2 MTWS - MW-5000 model, 640x480 VOx, NSN n/a
AN/PAS-13D(V)3 HTWS - CS-6000 model, 640x480 VOx, NSN 5855-01-538-8616