Exhibit 11 THERMO INSTRUMENT SYSTEMS INC. Computation of Earnings per Share Three Months Ended ----------------------------- March 29, March 30, 1997 1996 ------------------------------------------------------------------------ Computation of Fully Diluted Earnings per Share: Income: Net income $ 33,587,000 $ 34,043,000 Add: Convertible obligation interest, net of tax 2,031,000 1,348,000 ------------ ------------ Income applicable to common stock assuming full dilution (a) $ 35,618,000 $ 35,391,000 ------------ ------------ Shares: Weighted average shares outstanding 97,070,515 91,874,948 Add: Shares issuable from assumed conversion of convertible obligations 13,462,151 14,445,711 Shares issuable from assumed exercise of options (as determined by the application of the treasury stock method) 909,225 948,346 ------------ ------------ Weighted average shares outstanding, as adjusted (b) 111,441,891 107,269,005 ------------ ------------ Fully Diluted Earnings per Share (a)/(b) $ .32 $ .33 ============ ============