Uniformity of optical absorption in HgCdTe epilayer measured by infrared spectromicroscopy

Infrared absorption in HgCdTe epitaxial material has been investigated using infrared spectromicroscopy to study the uniformity at dimensions representative of typical infrared detectors. Infrared transmission measurements were performed on HgCdTe material using an infrared beam diameter of 9 μm. Line scans and area maps of transmission spectra were obtained to investigate statistical variations in infrared absorption. The HgCdTe material demonstrates a high degree of uniformity, with a standard deviation in absorption coefficient near the sensitive turn-on region of less than 3% and standard deviation in extracted Hg1-xCdxTeHg1-xCdxTe compositon of 3×10−4.3×10−4. © 2003 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69699/2/APPLAB-83-18-3701-1.pd

Acute changes in intra-alveolar tooth position and local clearance of 125I from the periodontal ligament

Changes in intra-alveolar tooth position and local 125I clearance from the periodontal ligament (PDL) were monitored simultaneously in cats. Axial tooth movements, reflecting periodontal ligament volume changes, were measured with an ultrasonic transit time technique. Local blood flow changes in the PDL were studied indirectly by measuring the local clearance of 125I-. Stimulation of the cervical sympathetic trunk caused an intrusive movement of the tooth with a concomitant reduction of the 125I- clearance. Infusion of noradrenaline induced a similar response. Stimulation of the inferior alveolar nerve during systemic treatment with phentolamine caused an extrusive movement of the tooth with a concomitant increase in the clearance of the tracer from the PDL. Intra-arterial infusion of the vasodilator substance P mimicked that response. Fixation of the tooth to the jaw bone, thus preventing an intrusive movement, did not change the reductions in clearance seen on sympathetic stimulation, indicating that this blood flow reduction was not dependent on tooth movement. A qualitative relation between PDL blood flow (as measured by local 125I clearance) and PDL volume (as measured by tooth position) is shown. The two variables measured are suggested to reflect two aspects of blood flow in the PDL