Fig. 1. Schematic illustration of reflection of the OAP and sketch of the Cartesian coordinate systems S (x, y, z) and S′(x′,y′,z′). Focus F of the OAP coincides with origins of the Cartesian coordinate systems. Inset shows beam propagation in the vicinity of focus F.

Fig. 2. Electromagnetic field intensity distributions focused by f/0.5 OAPs with h = 0 for (a1) |Ex′|2, (a2) |Ey′|2, (a3) |Ez′|2, (a4) |E′|2, (a5) |Hx′|2, (a6) |Hy′|2, (a7) |Hz′|2, (a8) |H′|2, and h = 360 mm for (b1)–(b8) with corresponding electromagnetic field components and the total field to (a1)–(a8).

Fig. 3. Focused electric field intensity transverse distributions of (a) |Ex′|2, (b) |Ez′|2, (c) |Ey′|2, (d) |E′|2, and (e) peak intensity as functions of offset h, and (f) total field |E′|2 for different h of 0 mm, 150 mm, 234 mm, and 360 mm. (g)(h) Intensity profiles for h = 0 and 234 mm in the lateral position between −3λ and 3λ.

Fig. 4. Peak intensity of electric total field focused by OAPs with different f as a function of offset h for various aperture sizes R of (a) 80 mm, (b) 120 mm, and (c) 160 mm. The dotted line represents the position of h = 1.25R.

Fig. 5. Offset of OAP in the optimum configuration, resulting in achievement of the maximum peak intensity, as a function of the parabola f-number.

Fig. 6. Tolerances of (a) OAP offset and (b) off-axis angle to a 5% decrease of the maximum focused peak intensity as functions of the parabola f-number.