An example method to perform optical measurements involves: emitting a first light beam via a first light source; performing first measurements by detecting the first light beam via a first optical sensor; emitting a second light beam via a second light source; performing second measurements by detecting the second light beam via a second optical sensor, the first and second measurements comprising variable components; performing third measurements by detecting a third light beam emitted from the second light source via a third optical sensor, the third measurements comprising a first steady state component representative of light intensities of the first and second light sources; and compensating a first light output of the first light beam and a second light output of the second light beam by controlling one or more currents to the first and second light sources based on the first steady state component of the third measurements.

An example method to perform optical measurements involves: emitting a first light beam via a first light source; performing first measurements by detecting the first light beam via a first optical sensor; emitting a second light beam via a second light source; performing second measurements by detecting the second light beam via a second optical sensor, the first and second measurements comprising variable components; performing third measurements by detecting a third light beam emitted from the second light source via a third optical sensor, the third measurements comprising a first steady state component representative of light intensities of the first and second light sources; and compensating a first light output of the first light beam and a second light output of the second light beam by controlling one or more currents to the first and second light sources based on the first steady state component of the third measurements.

A system and method for dividing a single mass flow into secondary flows of desired ratios to total flow. Each secondary flow line includes a pressure drop element, an absolute pressure sensor and a differential pressure sensor. The nonlinear relationship between flow and pressures can be transformed into a function of the absolute and differential pressures that has a linear relationship with the flow.

An example optical measurement system includes: a first light source configured to emit a first light beam; a first optical sensor configured to output first measurements based on detecting the first light beam; a second light source configured to emit a second light beam; a second optical sensor configured to output second measurements based on detecting the second light beam, wherein the first measurements and the second measurements comprise variable components; a third optical sensor configured to output third measurements based on detecting the second light beam or a third light beam, wherein the third measurements comprise a first steady state component; and a compensation circuit configured to control a first light output of the first light beam and a second light output of the second light beam by controlling current to the first light source and the second light source based on the third measurements.

An example optical measurement system includes: a first light source configured to emit a first light beam; a first optical sensor configured to output first measurements based on detecting the first light beam; a second light source configured to emit a second light beam; a second optical sensor configured to output second measurements based on detecting the second light beam, wherein the first measurements and the second measurements comprise variable components; a third optical sensor configured to output third measurements based on detecting the second light beam or a third light beam, wherein the third measurements comprise a first steady state component; and a compensation circuit configured to control a first light output of the first light beam and a second light output of the second light beam by controlling current to the first light source and the second light source based on the third measurements.

A measurement carrier includes a housing having an internal space, and a flow-rate measuring device located within the internal space. A bottom surface of the housing includes a first inflow hole, a second inflow hole, and an outflow hole, which provide fluid communication between the internal space and an outer space. The flow-rate measuring device may include a first flow-rate measuring sensor in fluid communication with the first inflow hole, and a second flow-rate measuring sensor in fluid communication with the second inflow hole.

A measurement carrier includes a housing having an internal space, and a flow-rate measuring device located within the internal space. A bottom surface of the housing includes a first inflow hole, a second inflow hole, and an outflow hole, which provide fluid communication between the internal space and an outer space. The flow-rate measuring device may include a first flow-rate measuring sensor in fluid communication with the first inflow hole, and a second flow-rate measuring sensor in fluid communication with the second inflow hole.

An example optical measurement system includes: a first light source configured to emit a first light beam; a first optical sensor configured to output first measurements based on detecting the first light beam; a second light source configured to emit a second light beam; a second optical sensor configured to output second measurements based on detecting the second light beam, wherein the first measurements and the second measurements comprise variable components; a third optical sensor configured to output third measurements based on detecting the second light beam or a third light beam, wherein the third measurements comprise a first steady state component; and a compensation circuit configured to control a first light output of the first light beam and a second light output of the second light beam by controlling current to the first light source and the second light source based on the third measurements.

An example optical measurement system includes: a first light source configured to emit a first light beam; a first optical sensor configured to output first measurements based on detecting the first light beam; a second light source configured to emit a second light beam; a second optical sensor configured to output second measurements based on detecting the second light beam, wherein the first measurements and the second measurements comprise variable components; a third optical sensor configured to output third measurements based on detecting the second light beam or a third light beam, wherein the third measurements comprise a first steady state component; and a compensation circuit configured to control a first light output of the first light beam and a second light output of the second light beam by controlling current to the first light source and the second light source based on the third measurements.

Techniques to provide a unified system for fluid pressure and fluid flowrate measurement are described. Upstream and downstream transducers include piezo devices, and are in contact with a fluid flow, such as in a pipe within a metering device. In an example, a first signal is sent from the upstream transducer to a downstream transducer, and time-of-flight of the first signal is measured. A second signal is sent from the downstream transducer to the upstream transducer, and a time-of-flight of the second signal is measured. A flowrate of the fluid flowing within the passage is calculated, based on the times of flight of the first and second signals. An electrical signal is sent to the first transducer. Upon conclusion of the electrical signal, a pressure of the fluid flowing within the passage is calculated, based at least in part on time of decay of a second electrical signal generated by vibration of the first transducer.