Financial Statement Components - Selected Financial Statement Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Inventories:
Raw materials and sub-assemblies	$ 23,506	$ 26,784
Work in process	10,347	12,862
Finished goods	4,984	8,103
Inventories	38,837	47,749
Inventories-delivered systems	2,457	2,856
Total inventories	41,294	50,605
Property, plant and equipment, net:
Total property, plant and equipment, gross	86,545	80,561
Accumulated depreciation and amortization	(42,319)	(36,068)
Total property, plant and equipment, net	44,226	44,493
Depreciation and amortization expense	6,800	6,900	$ 6,600
Accrued warranty	3,838	4,504	$ 2,953
Accrued taxes	290	646
Customer deposits	581	290
Retrofit liability	432
Fair value of current portion of contingent payments to Zygo Corporation related to acquisition		945
Accrued professional services	424	481
Accrued royalties	1,233	437
Other	1,249	1,575
Total other current liabilities	8,047	8,878
Land [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	15,568	15,569
Building and improvements [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	20,532	20,158
Machinery and equipment [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	35,659	32,995
Furniture and fixtures [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	2,282	2,266
Software [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	9,756	8,245
Capital in progress [Member]
Property, plant and equipment, net:
Total property, plant and equipment, gross	$ 2,748	$ 1,328