Exhibit 23.1 INDEPENDENT AUDITOR'S CONSENT We consent to the incorporation by reference in Registration Statement Nos. 333-08863, 333-32911, and 333-57331 of FEI Company on Form S-8 of our report dated February 26, 1999, appearing in Amendment No. 1 to the Annual Report on Form 10-K/A of FEI Company for the year ended December 31, 1998. DELOITTE & TOUCHE LLP DELOITTE & TOUCHE LLP Portland, Oregon April 26, 1999