Imaging devices maker OSI Systems Inc. said Thursday that its fiscal fourth quarter earnings fell 23 percent, largely due to weaker sales at its health care segment.

The Hawthorne company, which makes imaging systems for the security and health care fields, reported net income of $4.3 million (24 cents a share) in the quarter ended June 30, compared with $5.5 million (31 cents) a year earlier. Revenue fell 19 percent to $139 million.

Excluding one-time items, the company had adjusted profit of 29 cents a share, 1 cent better than the average forecast of analysts surveyed by Thomson Reuters, but the revenue figure was lower than the $148 million expected.

For the full year, revenue at the company’s security division, which makes airport screening systems, soared 167 percent but sales to cash-strapped hospitals and other health care providers in its older health care unit were off 14 percent. The company has been cutting costs and improving efficiency to boost profitability.

“The challenges of the global economy significantly impacted our sales throughout fiscal 2009,” Chief Executive Deepak Chopra said in a statement. “However, we have viewed this economic slowdown as an opportunity to adjust our cost structure to better position ourselves for improved profitability and cash flow going forward, while continuing to aggressively invest in product development.”

For fiscal 2010, the company said it expects earnings per share of $1.05 to $1.18, excluding charges, and forecast double digit sales growth at its security division.

Shares were down $1.46, or 7 percent, to $18.82 in midday trading on the Nasdaq.