Delta Optical Thin Film A/S celebrated the start of construction on a new facility with a cornerstone laying ceremony on Aug. 22. Delta Optical Thin Film celebrates the start of construction on its new facility. Courtesy of Delta Optical Thin Film. The 2300-sq.-m building has been designed with the potential for growth in mind. Located in the DTU Science Park, the facility will contain cleanrooms, offices, a canteen, and meeting rooms. The new facility is expected to be complete in autumn of 2020.