A new technology developed by Israeli dermatologists for treating psoriasis, vitiligo, atopic dermatitis and leukoderma has been cleared by the US Food and Drug Administration (FDA) to be marketed in the US. MultiClear, manufactured by CureLight Ltd., of Or Akiva, Israel, is a computer-controlled, targeted phototherapy system that uses both UVB and UVA rays. CureLight said the device allows "the exact matching of wavelengths and doses to optimally treat specific skin disorders." MultiClear will be featured at a forum at the American Academy of Dermatology's annual meeting, to be held Feb. 9 in Washington, D.C., and will be available in the US by March.   . . .    Heidenhain subsidiary IMT Masken und Teilungen AG, a Zurich, Switzerland, provider of optical reticles and large-area photomasks, has enlarged its production facility to 22,000 square feet, including class 10, 100 and 1000 cleanrooms. IMT, which is also a supplier of custom electro-optic modulators, said the increased space and technical capabilities will enable it to better provide complex products, such as etched-and-filled structures.   . . .   PSi Technologies announced it has signed a long-term supply agreement with Royal Philips Electronics to provide outsourced power semiconductor assembly and test services through PSi's facility in Chengdu, China. Philips said it will transfer its production of bipolar products, currently located in its assembly and test facility in the Philippines, to PSi in China, by 2005.