LTS-100 Laser Temperature Sensor

Non-intrusive Thermometry for Power Plant, Process Monitoring, and Aerospace Applications

LTS-100

MetroLaser, Inc., an innovator in the field of laser-based instrumentation, has developed the LTS-100^TM laser temperature sensor to enable measurement of gas temperatures up to 4000 °F with proper calibration.

Simple, Robust Design

The wavelengths of the LTS-100TM sensor are closely spaced and fall within the band used by telecommunications equipment. This allows a single communications-grade laser source to be used, leading to a simple, robust measurement system.

Insensitive to Obscurities

Obscurities in the beam path that may be caused by soot, dirty windows, or broadband absorption by other molecules are not a problem. Such obscurities have similar effects on each absorption feature, such that the absorption ratio remains constant. As a result, the LTS-100TM is essentially unaffected by these interferences.

High Temperature Capability

The highest measurable temperature is limited solely by the absorption characteristics of H2O molecules, since there is no physical contact with the gases being measured. Currently, the system has been validated up to 2800 °F, but future validations are planned for temperatures up to 4000 °F.

Physical Robustness

The laser beam is transmitted through a fiber-optic line that can be essentially unlimited in length. This property enhances the mechanical robustness of the system by allowing physical separation of the processing unit from the harsh combustion environment.

LTS-100 Laser Temperature Sensor

This laser-based sensor is well-suited for temperature measurement in the harsh environments found in power plants and aerospace, since the sensor is non-intrusive and has low sensitivity to particulates and other obscurities.

MetroLaser’s goals in marketing the LTS-100^TM are to improve the reliability and quality of traditionally challenging high temperature measurements.

SYSTEM INFORMATION

LTS-100TM operation is based on absorption of infrared light by hot H2O molecules, which is dependent on both gas temperature and light wavelength. By measuring the absorption that occurs at different laser wavelengths, the system can obtain the gas temperature. At left is a schematic of the LTS-100TM in a combustion temperature measurement application. A tunable diode laser generates a laser beam at a wavelength that is precisely modulated by a waveform generator. The beam is transmitted down the length of an optical fiber and enters the combustion chamber through a collimating lens and optical access port. A photodiode detector, mounted on the opposite side of the chamber, receives the transmitted laser light through a second optical access port. The photodiode detector output is sent to a laptop computer via a data acquisition board. Processing software on the laptop computes the gas temperature based on principles of absorption spectroscopy.

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MetroLaser will continue to pursue state-of-the-art research and development as well as the commercialization of optical diagnostics systems to measure flow velocity, temperature, chemical composition, surface temperature inside gas turbine engines, and non destructive inspection of composites and other components.