Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Apr. 01, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 47,417	$ 47,062
Marketable securities	84,679	82,899
Accounts receivable, net of allowances of $74 and $73, respectively	48,419	39,457
Inventories	41,544	38,837
Inventories-delivered systems	3,280	2,457
Prepaid expenses and other	5,925	5,667
Total current assets	231,264	216,379
Property, plant and equipment, net	43,176	44,226
Goodwill	9,227	8,940
Intangible assets, net	361	412
Deferred income tax assets	19,103	17,399
Other assets	405	474
Total assets	303,536	287,830
Current liabilities:
Accounts payable	18,614	11,342
Accrued payroll and related expenses	8,456	12,656
Deferred revenue	12,166	9,168
Other current liabilities	7,293	8,047
Income taxes payable	983	813
Total current liabilities	47,512	42,026
Deferred revenue	856	816
Income taxes payable	857	841
Deferred tax liability	21	20
Other long-term liabilities	377	353
Total liabilities	49,623	44,056
Commitments and contingencies (Note 9)
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: 25,227,935 and 25,070,889, respectively, issued and outstanding	25	25
Additional paid-in capital	273,735	271,969
Accumulated deficit	(15,737)	(22,174)
Accumulated other comprehensive income	(4,110)	(6,046)
Total stockholders’ equity	253,913	243,774
Total liabilities and stockholders’ equity	$ 303,536	$ 287,830