Model-Based Production of Infrared and Optical Materials.
Abstract
Intelligent Processing of Materials concepts that combine process modeling and simulation, in-situ sensors, and closed loop control were adapted and demonstrated on a vertical Bridgman (VB) for infrared (IR) and electrooptic materials. Models to simulate VB growth were developed. These models were used to investigate the dependence of the solid liquid shape interface and thermomechanical stresses in the crystal on furnace temperature profile, ampoule geometry and support, and growth rate. Two types of sensors were investigated: an IR sensor and an eddy current sensor. The experimental results showed that it is not possible to image the solidification front during growth with an IR sensor through the In:CdTe crystal because of the low optical transmission and high thermal emission of ln:CdTe at high temperature. Changes in electrical conductivity become measurable using an encircling type eddy current sensor when the processing temperature exceeds 600 C. The eddy current sensor response can be used to monitor specimen quality. As a result, the eddy current sensor is critical for development of a flexible growth system to produce the material under favorable growth conditions and ensure reliable delivery with low cost. The potential applications of the technologies include infrared focal plane arrays and electrooptic modulators for CO2 and surgical lasers.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1995
- Accession Number
- ADA303886
Entities
People
- Philip A. Parrish
- Tony F. Zahrah
Organizations
- Braddock Dunn & McDonald