I finally got around to writing a page about optical coupling compounds: http://www.logwell.com/tech/servtips/optical_coupling_grease.html Comments or criticisms needed and much appreciated. Syd H. Levine AnaLog Services, Inc. Phone: (270) 276-5671 Telefax: (270) 276-5588 E-mail: analog at logwell.com Web URL: www.logwell.com