The Grating Light Valve diffractive MOEMS device has been successfully used in imaging applications (lithography and display) requiring image data-rates of 1-5 giga-bits per second (Gb/s). However, new applications such as maskless photolithography and high performance displays require larger pixel counts and finer control of gray-scale. This paper discusses the suitability of the GLV device for high data-rate applications. It discusses the factors governing GLV device switching speed and illustrates how these properties are optimized relative to other requirements of the imaging system.
Three novel atmosphere gas composition monitoring methods are described that could significantly improve the quality control of steel heat treat processes. The proposed methods, gas chromatography, inter-cavity Raman analysis, and fiber- optic Raman analysis are in different stages of development but all have varying advantages over the current state of the art IR analysis. A summary description of the Raman principle is provided. Test results comparing the inter- cavity Raman analysis versus the gas chromatography analysis are given. The major disadvantage of the gas chromatography is the slow response. The cost-effective inter-cavity Raman device can monitor eight species simultaneously with a response in the order of tens of milliseconds. An in-situ fiber optic Raman analysis instrument is expanded and carburizing facility test with this novel device are described. Advantages of the fiber-optic instrument are the in-situ nature and the fast response. This instrument lends itself to be readily used in applications where hostile environments require monitoring.
Localized velocity, temperature, and species concentration measurements in rocket flow fields are needed to evaluate predictive computational fluid dynamics (CFD) codes and identify causes of poor rocket performance. Velocity, temperature, and total number density information have been successfully extracted from spectrally resolved Rayleigh scattering in the plume of small hydrogen/oxygen rockets. Light from a narrow band laser is scattered from the moving molecules with a Doppler shifted frequency. Two components of the velocity can be extracted by observing the scattered light from two directions. Thermal broadening of the scattered light provides a measure of the temperature, while the integrated scattering intensity is proportional to the number density. Spontaneous Raman scattering has been used to measure temperature and species concentration in similar plumes. Light from a dye laser is scattered by molecules in the rocket plume. Raman spectra scattered from major species are resolved by observing the inelastically scattered light with a linear array mounted to a spectrometer. Temperature and oxygen concentrations have been extracted by fitting a model function to the measured Raman spectrum. Results of measurements on small rockets mounted inside a high altitude chamber using both diagnostic techniques are reported.
Conference Committee Involvement (2)
Optical On-Line Industrial Process Monitoring
22 September 1999 | Boston, MA, United States
Advanced Sensors and Monitors for Process Industries and the Environment