An optical measuring device, for measuring a wavelength of a response from a sensing device, the optical measuring device comprising - a light path coupled to an interface for coupling the light path to the sensing device; - a periodic optical filter with an input coupled to the light path, to sample light that is supplied to or received from the sensing device; - a first detector coupled to an output of the periodic optical filter; - a continuous output optical filter with an input coupled to the light path to sample light that is supplied to or received from the sensing device, the continuous output optical filter having a continuously variable output amplitude as a function of wavelength, having no local minima or maxima in its wavelength dependent intensity transfer function as a function of wavelength in an operational wavelength range; - a second detector coupled to an output of the continuous output optical filter; - a third detector coupled to the output of the sensing device; - a computation circuit coupled to the first, second and third detector (128a, b, c), and configured to process output signals from the first, second and third detector (128a, b,c) obtained during a wavelength scan of light supplied through the light path, using quantization of data derived from the second detector to identify wavelengths associated with respective time points at which the wavelength scan reaches corresponding positions in respective periods of the periodic optical filter, and to compute a wavelength associated with the response of the sensing device from the identified wavelengths on the basis of a temporal relation between said respective time points and a time point of the response of the sensing device. - a light path coupled to an interface for coupling the light path to the sensing device; - a periodic optical filter with an input coupled to the light path, to sample light that is supplied to or received from the sensing device; - a first detector coupled to an output of the periodic optical filter; - a continuous output optical filter with an input coupled to the light path to sample light that is supplied to or received from the sensing device, the continuous output optical filter having a continuously variable output amplitude as a function of wavelength, having no local minima or maxima in its wavelength dependent intensity transfer function as a function of wavelength in an operational wavelength range; - a second detector coupled to an output of the continuous output optical filter; - a third detector coupled to the output of the sensing device; - a computation circuit coupled to the first, second and third detector (128a, b, c), and configured to process output signals from the first, second and third detector (128a, b,c) obtained during a wavelength scan of light supplied through the light path, using quantization of data derived from the second detector to identify wavelengths associated with respective time points at which the wavelength scan reaches corresponding positions in respective periods of the periodic optical filter, and to compute a wavelength associated with the response of the sensing device from the identified wavelengths on the basis of a temporal relation between said respective time points and a time point of the response of the sensing device.