Oxford Instruments Superconductivity is axing 30 jobs as part of a major restructuring programme.
The majority of the jobs will be lost at its sites in Tubney Woods, near Abingdon, and Eynsham, with the rest in its overseas operations.
It is the second round of job cuts in two years for the firm, after 100 positions were axed in 2002.
Marketing director Frank Trundle said a decision had been taken to concentrate on two core areas of the business and move away from its "legacy systems" which include the construction of huge magnets used by scientists to analyse molecules, including proteins and genes.
The core areas will be physical sciences, which involves selling equipment to universities and analytical instruments, selling magnet technology to manufacturers of equipment involved in pharmaceutical and biochemical research.
A new team has been set up to find opportunities in the biomedical field. Mr Trundle added: "There was a need to reduce the costs of the business and these people who have gone will address that."
The 30 people affected have been notified and external conultants are being brought in to help them find work elsewhere. The latest redundancies leave 380 workers at Eynsham and Tubney.
The job losses are the latest in a turbulent recent history for Oxford Instruments, which started as the original Oxford University spin-off company 40 years ago.
While the headquarters are in Eynsham, only the Superconductivity arm remains in Oxfordshire following the closure three years ago of two Oxford Instruments buildings in Abingdon and one in Oxford.
Last year's financial figures revealed Superconductivity was the only one of three divisions to increase profitability, but at the expense of 100 jobs in 2002.
In November, Oxford Intruments sold its 49 per cent share in Eynsham-based Oxford Magnet Technology to German partner Siemens for £9.1m. Siemens later made 81 workers redundant.
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