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Table 2 Calculated performance parameters of a telemicroscope in dependence on the focal length (extension tube length: \(l=50\) mm; f-number: \(N=2.8\); sensor size: 7.04 mm × 5.28 mm; pixel size: 4.4 μm × 4.4 μm; circle of confusion: \(c_{\mathrm{max}}=0.0059\) mm)

From: In situ erosion measurement tools for electric propulsion thrusters: triangular laser head and telemicroscope

f [mm] \(s_{2}\) [mm] \(s_{1}\) [mm] M \(w_{1}\) [mm] \(h_{1}\) [mm] \(s_{\mathrm{h}}\) [m] \(s_{\mathrm{n}}\) [mm] \(s_{\mathrm{f}}\) [mm] \(s_{\mathrm{f}}-s_{\mathrm{n}}\) [mm] \(w_{1}^{\mathrm{pix}}=h_{1}^{\mathrm{pix}}\) [μm] lat. res. [μm]
4 54.0 4.3 12.50 0.56 0.42 0.98 4.30 4.34 0.04 0.35 0.7
8 58.0 9.3 6.25 1.13 0.84 3.90 9.26 9.30 0.04 0.70 1.4
16 66.0 21.1 3.13 2.25 1.69 15.60 21.09 21.15 0.06 1.41 2.8
25 75.0 37.5 2.00 3.52 2.64 38.07 37.46 37.54 0.07 2.20 4.4
33 83.0 54.8 1.52 4.65 3.48 66.33 54.73 54.83 0.09 2.90 5.8
50 100.0 100.0 1.00 7.04 5.28 152.24 99.93 100.07 0.13 4.40 8.8
75 125.0 187.5 0.67 10.56 7.92 342.51 187.40 187.60 0.21 6.60 13.2
100 150.0 300.0 0.50 14.08 10.56 608.87 299.85 300.15 0.30 8.80 17.6
150 200.0 600.0 0.33 21.12 15.84 1369.87 599.74 600.26 0.53 13.20 26.4
200 250.0 1000.0 0.25 28.16 21.12 2435.26 999.59 1000.41 0.82 17.60 35.2