Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Operating activities:
Net loss	$ (3,048)	$ (3,603)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	211	193
Change in fair value of earn-out liability	74	29
Stock-based compensation	615	428
Provision for doubtful accounts	25
Changes in operating assets and liabilities:
Accounts receivable	638	1,463
Inventories	66	75
Prepaid expenses and other current assets	(221)	(181)
Other long-term assets	9	(27)
Accounts payable	(116)	252
Accrued compensation	(1,417)	(718)
Accrued expenses	(523)	164
Accrued warranty	(153)	(620)
Deferred revenue	43	(275)
Other long-term liabilities		93
Net cash used in operating activities	(3,797)	(2,727)
Investing activities:
Acquisition of property and equipment	(67)	(274)
Payment on earn-out liability	(96)	(92)
Net cash used in investing activities	(163)	(366)
Financing activities:
Proceeds from stock option exercises		23
Taxes paid related to net share settlements of equity awards	(93)	(138)
Net cash provided by financing activities	(93)	(115)
Effect of foreign exchange rate changes	34	23
Net decrease in cash and cash equivalents	(4,019)	(3,185)
Cash and cash equivalents, beginning of period	21,194	21,707
Cash and cash equivalents, end of period	17,175	18,522
Supplemental disclosure of non-cash activities:
Transfer of inventory to property and equipment	$ 17	$ 60