<title>Electrochemically deposited nickel alloys with controlled thermal expansion for optical applications</title>

Abstract

Electrochemically grown nickel-based alloys (electroless nickel) are currently used as a polishable coating on lightweight metal and nonmetal substrates for high performance applications ranging from large spaceborne telescopes to cryogenically cooled optical instruments. The performance of nickel plated optics is currently limited by bi-metallic dimensional stability issues. OCA has determined that careful selection of processing parameters and plating bath chemistries leads to a family of coatings whose thermal expansion curves can be tailored to better match those of ultra-lightweight substrate materials of interest over useful temperature ranges. This paper presents a discussion on the nature of the thermal expansion mismatch and a description of the fundamental methodology used in developing stable EN-substrate couples.