Optical fields become comparable only after pixel mapping closes. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Magnification fixes the image field

A 3 m sample segment at magnification 4 gives image length 12 m.

Limage=3 m4=12 mL_{\text{image}}=3\ \text{m}\cdot4=12\ \text{m}
Pixel mappingMagnification and pixels bind image length to addresses.sampleimagecovered3 m12 m6 px each 2 m4 fields -> 48 m

Fields are addressable optical tiles

The field has 6 pixels, so one pixel spans 2 m. The checked tile count is 4 fields.

Nfields=4N_{\text{fields}}=4
Pixel mappingMagnification and pixels bind image length to addresses.sampleimagecovered3 m12 m6 px each 2 m4 fields -> 48 m