The invention relates to an SPR (
surface plasmon resonance) phase measurement method for measuring thickness of a nano
metal film. The method comprise the steps of 1, establishing a
standard curve graph of the variation of a
phase variation difference of a TM polarized wave and a TE polarized wave with the thickness of the
metal film, and obtaining a corresponding fitting formula, 2, obtaining a
coating interference fringe image of a
film coating area of a
prism SPR sensor, 3, obtaining an interference fringe image of a non-
film coating area of the
prism SPR sensor, 4, comparing and calculating the images obtained in Step 2 and Step 3, and obtaining the
phase variation difference of the TM polarized wave and the TE polarized wave in the
film coating area, and 5, substituting a
calculated result in Step 4 into the fitting formula of the
standard curve graph in Step 1, and obtaining a value of the thickness of the
metal film. The SPR phase measurement method has the benefits that
phase modulation is conducted on the TM polarized wave and the TE polarized wave by
laser interference, so that non-contact, high-precision and convenient-to-operate measurement of the thickness of the nano metal film can be achieved.