Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 26, 2015	Dec. 27, 2014	Dec. 28, 2013
Cash flows from operating activities:
Net income (loss)	$ 2,905	$ (31,118)	$ (14,146)
Reconciliation of net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	9,075	9,767	8,787
Stock-based compensation	6,248	6,752	7,674
Excess tax benefit from equity awards	0	0	53
Disposal of fixed assets	1,121	249	177
Inventory write-down	2,645	2,897	7,579
Deferred income taxes	345	17,915	(6,889)
Changes in fair value of contingent payments to Zygo Corporation	(56)	201	1,325
Changes in assets and liabilities:
Accounts receivable	(12,610)	3,861	(10,376)
Inventories	(16,431)	(7,173)	(7,024)
Inventories-delivered systems	(943)	4,988	(4,627)
Prepaid expenses and other	3,271	2,303	(1,855)
Accounts payable, accrued and other liabilities	4,167	1,790	4,840
Deferred revenue	1,006	(12,855)	12,717
Income taxes payable	828	(212)	(666)
Net cash provided by (used in) operating activities	1,571	(635)	(2,431)
Cash flows from investing activities:
Sales of marketable securities	3,383	0	0
Maturities of marketable securities	41,863	38,839	47,089
Purchases of marketable securities	(41,449)	(41,100)	(49,182)
Purchases of property, plant and equipment	(1,846)	(5,792)	(5,689)
Net cash provided by (used in) investing activities	1,951	(8,053)	(7,782)
Cash flows from financing activities:
Payments to Zygo Corporation related to acquisition	(851)	(587)	(1,004)
Repayments of debt obligations	0	0	(5,224)
Proceeds from sale of shares under employee stock option plans and purchase plan	3,974	5,958	4,967
Excess tax benefit from equity awards	0	0	(53)
Taxes paid on net issuance of stock awards	(1,182)	(702)	(1,181)
Repurchases of common stock	(1,721)	(5,344)	(5,000)
Net cash provided by (used in) financing activities	220	(675)	(7,495)
Effect of exchange rate changes on cash and cash equivalents	(264)	(726)	(442)
Net increase (decrease) in cash and cash equivalents	3,478	(10,089)	(18,150)
Cash and cash equivalents, beginning of period	34,676	44,765	62,915
Cash and cash equivalents, end of period	38,154	34,676	44,765
Supplemental disclosure of cash flow information:
Cash paid for interest	0	0	232
Cash paid (refund) for income taxes, net	(826)	861	313
Supplemental disclosure of non-cash investing activities:
Transfer of inventory to property, plant and equipment, net	$ 1,469	$ 3,275	$ 3,145