Safeway Stores Inc., the nation's largest supermarket chain, said yesterday that earnings rose 14.8 percent in the 17-week period ended Jan. 3 to $41.8 million ($1.60 a share) but declined 16.8 percent for the year.

In another earnings reports Polaroid posted improved 1980 earnings on modest sales.

Safeway's fourth-quarter profits came on sales of $5 billion and compared with earnings of $36.41 million ($1.40) in the same 1979 period on sales of $4.36 billion.

For all of 1980, the company said profits fell to $119.3 million ($.57) from $143.3 million ($5.49) in 1979. Sales totaled $15.1 billion for the 53 weeks ended Jan. 3, up about 10 percent from sales of $13.7 billion for the 52 weeks ended Dec. 29, 1979.

Polaroid Corp. reported yesterday that earnings more than doubled last year to $85.4 million ($2.60 a share) even though sales increased only modestly.

William J. McCune Jr., Polaroid's president and chief executive officer, said profits compared with $36.1 million ($1.10) in 1979 and that worldwide sales rose 7 percent to $1.45 billion from $1.36 billion in 1979.

Fourth-quarter earnings were $32.3 million (98 cents), up from $28.( million (88 cents) in the last three month of 1979. Sales rose 8 percent to $460.5 million from $426.6 million in the same 1979 period.