Electro Scientific Industries, Inc. (ESI) is an American high technology company headquartered in the Portland, Oregon, metropolitan area, specifically in Beaverton, Oregon, since 2021, but from 1963–2021 it was based in the unincorporated Cedar Mill area just north of Beaverton. ESI is a developer and supplier of photonic and laser systems for microelectronics manufacturers. Founded in 1944, it is the oldest high-tech company in Oregon. Along with Tektronix, and later Intel, it has spawned numerous technology-based companies in the Portland area, an area known as the Silicon Forest. From 1983 to 2019, shares in the company were publicly traded on NASDAQ, under the ticker symbol ESIO. In October 2018, it was announced that a deal had been reached to sell the company to MKS Instruments, Inc. The deal was completed on February 1, 2019, making ESI a subsidiary of MKS. History ESI was founded in 1944 as Brown Engineering, later becoming Brown Electro-Measurement Corporation (BECO). In 1953, BECO's Douglas C. Strain and three other investors bought out Strain's partners at Brown and formed a new company, Electro-Measurements Inc., which used the brand name "ESI" in marketing. The acronym stood for "excellent scientific instruments", but the company's name remained Electro Measurements Inc. until 1959, when it was changed to "ESI, Inc." and finally in 1960 to Electro Scientific Industries, Inc. (ESI). Prior to about 2000, the company was usually referred to as having been founded in 1953. Douglas Strain was the company's CEO and board chairman from 1953 until 1980 and remained on the board (continuing as chairman until 1985, then vice chairman) until fully retiring in 1999. In the 1950s, the company's specialty was the manufacture of high-precision resistance measuring instruments and related products. In 1970, ESI began developing laser trimming systems for resistor circuits, and soon became a leader in this field. All facilities were located at S.E. 43rd & Stark in Portland until 1956, when the first stage of a new headquarters and manufacturing plant on Macadam Avenue, in South Portland, was opened. The new plant was destroyed by fire in 1957 and had to be rebuilt. In 1962, ESI announced plans to create a new development called "Sunset Science Park", to be built in the Cedar Mill area of unincorporated Washington County, Oregon, designed to attract other technology companies, with ESI as an anchor. The company moved its headquarters to the Sunset Science Park location in 1963,