The actual optical system cannot achieve strict temperature
compensation, that is, in a certain temperature range, the image surface of the
system cannot be consistent with the change of the lens barrel with complex
structure, which requires an Error tolerance for temperature compensation.
In a broad sense, the image defocuses caused by temperature can be
regarded as a kind of aberration. According to the Rayleigh law of optical
system aberration, the temperature compensation error should be controlled at
its maximum wave aberration less than 1/4 wavelength.