Patent ID: 8436296

Claim:
An apparatus deployable downhole for fluid analysis, comprising: a source generating an optical signal across a spectrum of wavelengths and routing the optical signal concurrently at a same time into a reference channel and a measurement channel; at least one movable element having a plurality of filters distributed thereon, the filters concurrently filtering the reference and measurement channels at a same time, the at least one movable element movable to change which of the filters filter the reference and measurement channels at the same time; at least one drive operable to move the at least one movable element; control circuitry electrically coupled to the source and the at least one drive, the control circuitry controlling illumination of the source and movement of the at least one movable element; and a detection unit concurrently detecting at a same time (a) the reference channel, after interaction with one of the filters of the at least one movable element, and (b) the measurement channel, after interaction with the same filter of the at least one movable element and a fluid sample, wherein the concurrent filtering and detection of the reference and measurement channels are matched at the same time by the same filter of the at least one movable element and account for a variable condition in the apparatus.