Table 2: Imaging feature of the object with different depth.

r/mh/mLong axis (a)Short axis (b)Hyperbolic formula

0.050.050.0890.104
0.050.100.1330.159
0.050.200.2310.228
0.050.300.3300.379
0.050.400.4300.487
0.050.500.5310.598
0.050.600.6320.713