Condensed Consolidated Statements of Cash Flows (USD $) In Thousands	9 Months Ended
	Oct. 01, 2011	Oct. 02, 2010
Cash flows from operating activities:
Net income	$ 29,216	$ 29,820
Reconciliation of net income to net cash provided by operating activities:
Depreciation and amortization	4,722	4,462
Asset impairment	0	463
Stock-based compensation	2,746	2,741
Excess tax benefit from equity awards	(1,925)	(664)
Loss (gain) on disposal of fixed assets	19	(193)
Inventory write down	1,294	1,156
Deferred income taxes	2,386	113
Unrealized foreign exchange transaction (gain) loss	0	(523)
Changes in fair value of contingent payments to Zygo Corporation	434	471
Changes in assets and liabilities:
Accounts receivable	(259)	(18,307)
Inventories	(11,209)	(7,620)
Inventories-delivered systems	(477)	855
Prepaid expenses and other assets	130	(140)
Accounts payable, accrued and other liabilities	2,889	11,477
Deferred revenue	3,313	(517)
Income taxes payable	2,131	1,093
Net cash provided by operations	35,410	24,687
Cash flows from investing activities:
Payments to Zygo Corporation related to acquisition	(301)	(3,478)
Purchases of property, plant and equipment	(2,082)	(1,953)
Proceeds from sale of property, plant and equipment	0	492
Net cash used in investing activities	(2,383)	(4,939)
Cash flows from financing activities:
Repayments of debt obligations	(2,389)	(2,909)
Proceeds from sale of shares under employee stock plans	5,291	3,883
Stock offering costs	0	(28)
Excess tax benefit from equity awards	1,925	664
Taxes paid on net issuance of stock awards	(46)	(249)
Repurchases of common stock	(4,257)	(1,320)
Net cash provided by financing activities	524	41
Effect of exchange rate changes on cash and cash equivalents	138	681
Net increase in cash and cash equivalents	33,689	20,470
Cash and cash equivalents, beginning of period	66,460	43,526
Cash and cash equivalents, end of period	$ 100,149	$ 63,996