Luminus Devices Inc., developer of high performance solid-state light sources out of Billerica, Mass., has announced that Ellen Richstone has joined the company as executive vice president and chief financial officer. With extensive experience in public and private companies, international business and M&A, Richstone will be responsible for implementing and managing worldwide finance, administrative, human resources, legal and IT operations. Prior to joining Luminus Devices, Richstone served as CFO at Sonus Networks, where she implemented financial processes to enable growth. Previously, Richstone served as president and CEO of Entrepreneurial Resources Group, a global professional services firm founded more than 10 years ago. Richstone also served as CFO and senior vice president, finance and administration at Brooks Automation, a hardware and software provider to the semiconductor industry. She has also held executive management positions at companies including Augat Inc., Rohr Aerospace and Bull (Honeywell Bull) and Data General. Richstone currently serves on the board of directors at Blue Shift Technologies and is the non-executive Chairman of the Entrepreneurial Resources Group. She also served on the board of American Power Conversion (APC) as its SEC Financial Expert before its sale for $6 billion in 2007.