Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018		Apr. 01, 2017
Operating activities:
Net loss	$ (3,603)		$ (1,866)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	193		207
Change in fair value of earn-out liability	29		25
Stock-based compensation	428		392
Changes in operating assets and liabilities:
Accounts receivable	1,463		1,159
Inventories	75		(85)
Prepaid expenses and other current assets	(181)		(118)
Other long-term assets	(27)		5
Accounts payable	252		(50)
Accrued compensation	(718)		(777)
Accrued expenses	164		(541)
Accrued warranty	(620)		46
Deferred revenue	(275)		(22)
Other long-term liabilities	93		3
Net cash used in operating activities	(2,727)		(1,622)
Investing activities:
Acquisition of property and equipment	(274)		(341)
Payment on earn-out liability	(92)		(84)
Net cash used in investing activities	(366)		(425)
Financing activities:
Proceeds from issuance of common stock, net of issuance costs			2,263
Proceeds from stock option exercises	23		163
Taxes paid related to net share settlements of equity awards	(138)		(268)
Net cash (used in) provided by financing activities	(115)		2,158
Effect of foreign exchange rate changes	23
Net (decrease) increase in cash and cash equivalents	(3,185)		111
Cash and cash equivalents, beginning of period	21,707	[1]	23,747
Cash and cash equivalents, end of period	18,522		$ 23,858
Supplemental disclosure of non-cash activities:
Transfer of inventory to property and equipment	$ 60

[1] Derived from the audited consolidated financial statements included in the Annual Report on Form 10-K filed with the SEC for the year ended December 30, 2017.