Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 28, 2015	Dec. 27, 2014
Current assets:
Cash and cash equivalents	$ 27,935	$ 34,676
Marketable securities	49,114	49,286
Accounts receivable, net of allowances of $212 and $253, respectively	39,072	26,121
Inventories	37,487	35,105
Inventories-delivered systems	749	1,912
Prepaid expenses and other	9,493	9,289
Deferred income tax assets	1,455	1,457
Total current assets	165,305	157,846
Property, plant and equipment, net	47,800	49,633
Goodwill	9,391	10,494
Intangible assets, net	3,326	4,294
Deferred income tax assets	393	410
Other assets	554	559
Total assets	226,769	223,236
Current liabilities:
Accounts payable	11,913	10,199
Accrued payroll and related expenses	10,807	8,700
Deferred revenue	8,054	10,021
Other current liabilities	8,110	8,265
Income taxes payable	924	1,017
Total current liabilities	39,808	38,202
Deferred revenue	2,090	2,591
Income taxes payable	723	701
Deferred tax liabilities	962	926
Other long-term liabilities	1,348	1,279
Total liabilities	44,931	43,699
Commitments and contingencies (Note 11)
Stockholders’ equity:
Preferred stock, $0.001 par value; 3,000,000 shares authorized; no shares issued or outstanding	0	0
Common stock, $0.001 par value, 47,000,000 shares authorized: 23,973,819 and 23,813,729, respectively, issued and outstanding	24	24
Additional paid-in capital	252,839	251,396
Accumulated deficit	(66,558)	(69,114)
Accumulated other comprehensive income (loss)	(4,467)	(2,769)
Total stockholders’ equity	181,838	179,537
Total liabilities and stockholders’ equity	$ 226,769	$ 223,236