Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Apr. 02, 2011
Cash flows from operating activities:
Net income	$ 1,703	$ 10,510
Reconciliation of net income to net cash provided by (used in) operating activities:
Depreciation and amortization	2,087	1,428
Stock-based compensation	1,461	822
Excess tax benefit from equity awards	(645)	(2,236)
Loss (gain) on disposal of fixed assets	118	0
Inventory write down	509	273
Deferred income taxes	2,468	1,467
Changes in fair value of contingent payments to Zygo Corporation	8	147
Changes in assets and liabilities:
Accounts receivable	(9,617)	(3,602)
Inventories	(713)	(1,657)
Inventories-delivered systems	(61)	(1,065)
Prepaid expenses and other	(2,337)	562
Accounts payable, accrued and other liabilities	(1,166)	(2,567)
Deferred revenue	2,731	3,393
Income taxes payable	518	3,024
Net cash provided (used in) by operating activities	(2,936)	10,499
Cash flows from investing activities:
Payments to Zygo Corporation related to acquisition	(107)	(61)
Purchases of property, plant and equipment	(867)	(755)
Net cash used in investing activities	(974)	(816)
Cash flows from financing activities:
Repayments of debt obligations	(186)	(186)
Proceeds from sale of shares under employee stock option plans and purchase plan	1,214	1,603
Excess tax benefit from equity awards	645	2,236
Taxes paid on net issuance of stock awards	(16)	(23)
Net cash provided by financing activities	1,657	3,630
Effect of exchange rate changes on cash and cash equivalents	32	398
Net increase (decrease) in cash and cash equivalents	(2,221)	13,711
Cash and cash equivalents, beginning of period	97,699	66,460
Cash and cash equivalents, end of period	$ 95,478	$ 80,171