Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 29, 2014	Mar. 30, 2013
Cash flows from operating activities:
Net income (loss)	$ 1,595	$ (5,582)
Reconciliation of net income (loss) to net cash used in operating activities:
Depreciation and amortization	2,429	2,108
Stock-based compensation	1,634	1,457
Excess tax benefit from equity awards	0	367
Loss on disposal of fixed assets	0	12
Inventory write-down	669	1,321
Deferred income taxes	519	(4,065)
Changes in fair value of contingent consideration	(5)	389
Changes in assets and liabilities:
Accounts receivable	(967)	1,268
Inventories	(3,142)	(5,631)
Inventories-delivered systems	4,652	750
Prepaid expenses and other	1,845	592
Accounts payable, accrued and other liabilities	(2,536)	(351)
Deferred revenue	(10,619)	(796)
Income taxes payable	(766)	(360)
Net cash used in operating activities	(4,692)	(8,521)
Cash flows from investing activities:
Maturities of marketable securities	7,000	10,111
Purchases of marketable securities	(8,410)	(11,292)
Purchases of property, plant and equipment	(2,193)	(997)
Net cash used in investing activities	(3,603)	(2,178)
Cash flows from financing activities:
Payments of contingent consideration	(100)	(133)
Repayments of debt obligations	0	(227)
Proceeds from sale of shares under employee stock option and purchase plans	3,115	1,598
Excess tax benefit from equity awards	0	(367)
Taxes paid on net issuance of stock awards	(659)	(86)
Repurchases of common stock	0	(5,000)
Net cash provided by (used in) financing activities	2,356	(4,215)
Effect of exchange rate changes on cash and cash equivalents	7	(656)
Net decrease in cash and cash equivalents	(5,932)	(15,570)
Cash and cash equivalents, beginning of period	44,765	62,915
Cash and cash equivalents, end of period	$ 38,833	$ 47,345