Table 1. The measurement of RI of standard samples^a.

	Meas	Ref	Err
Water	1.336 ± 0.003	1.329 [29]	~1%
Air	1.005 ± 0.003	1.0003 [30]	~1%
Oil	1.515 ± 0.004	1.5151	~1%
Cover glass	1.576 ± 0.002	1.56 ± 0.012	—

       ^aMeas: measured value (average ± standard deviation); Ref: reference value; Err: error with respect to the reference value. The error has already taken into account the standard deviation. 1: From Nikon type A immersion oil specification (23°C). 2: The RI of cover glass is measured using the focus tracking method [1].