Method and device for compensating for interfering variables in an optical sensor

A method of compensating for an interfering variable in an optical sensor, which produces a measurement of an intended variable using an optical signal, the measurement being influenced by a wavelength of the optical signal and by the interfering variable, the method comprising:

• feeding the optical signal to a compensation element, which is located where the interfering variable is present, the optical signal being reflected in the compensation element to produce a reflected optical signal;
• feeding the reflected optical signal to said optical sensor the optical sensor and the compensation element producing corresponding effects as a result of the interfering variable;
• and
• allowing a wavelength change in the optical signal during reflection in the compensation element as a result of the interfering variable such that in the optical sensor where the interfering variable is present, the influences on the measurement by the wavelength change and by the interfering variable substantially cancel one another out.