Optical wavelength interrogator

An optical wavelength readout system for application in optical sensing systems, comprising:

• a master unit, comprising:
• a wavelength swept optical source for launching light into a string of optical sensors;
• a master detection and processing unit for detecting and processing the light emitted by the source;
• and
• a wavelength reference unit adapted to make a reference signal available to other parts of the readout system, wherein the reference signal represents a generally exact relation between the wavelength of the light emitted from the source and time;
• and
• a slave unit having a light coupling device for coupling light from the optical source into the string of optical sensors and for coupling light reflected from the string of optical sensors to a slave detection and processing unit arranged to detect and process the reflected light, wherein light passing through the wavelength reference unit is directed to the master detecting and processing unit while being isolated from the slave detection and processing unit.