The invention discloses a method for measuring the
reflectivity of a dual-
wavelength high reflecting mirror. The method comprises the following steps: injecting the continuous lasers of two different wavelengths with periodically modulated
light intensity into a stable initial
optical resonance cavity composed of two or three dual-
wavelength high reflecting mirrors at the same time; when the amplitude of the output
signal of the initial
optical resonance cavity is higher than a set threshold,
cutting off the incident
laser beam and recording the cavity ring-down
signal; or recording the cavity ring-down
signal at the falling edge of a modulation signal, and obtaining the ring-down time [tau]01 and [tau]02 of the initial
optical resonance cavity at the two
laser wavelengths by use of a synchronous measurement method, spectral detection method or alternate measurement method, and calculating the average
reflectivity R01 and R02 of a cavity mirror at the two wavelengths; similarly, adding a dual-
wavelength high reflecting mirror to be measured into the initial optical
resonance cavity according to the using angle so as to form a stable test optical
resonance cavity; obtaining the ring-down time [tau]01 and [tau]02 of the test optical
resonance cavity at the two
laser wavelengths by use of a synchronous measurement method, spectral detection method or alternate measurement method; and obtaining the
reflectivity R1 and R2 of the dual-wavelength high reflecting mirror to be measured at the two wavelengths.