Spectra-Physics of Mountain View, Calif., has announced that it expects to report lower-than-anticipated sales for the quarter ending April 2, 1999. It foresees sales between $30 million and $32 million, compared with net sales of $43.6 million for the same quarter last year The company attributes the decline to a general weakness in demand in several niche application markets, including those for high-power semiconductor-based lasers. Other factors that contributed to lackluster sales include a slowdown in the commercial printing and graphics market and continued weakness in the semiconductor and disk drive markets. In an effort to bring costs and expenses in line with its revised revenue projections, Spectra-Physics plans to reduce its work force by about 7 percent.