Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (6,214)	$ (6,254)
Adjustments to reconcile net loss to net cash used in operating activities:
Provision for doubtful accounts	238	(65)
Depreciation and amortization	2,650	3,527
Deferred income taxes	0	71
Loss on disposals of fixed assets	54	56
Compensation expense related to stock-based awards and employee stock purchase plan	805	874
Unrealized currency translation (gain) loss	(1,065)	1,082
Changes in operating assets and liabilities:
Accounts receivable	3,577	944
Inventories	(2,094)	(3,117)
Prepaid expenses, other current assets and current contract assets	(243)	952
Other non-current assets and non-current contract assets	(47)	1,236
Accounts payable	(1,174)	2,627
Contract liabilities and long-term contract liabilities	317	(1,254)
Accrued compensation, product warranty and other	246	(1,738)
Other long-term liabilities	2	(15)
Net cash used in operating activities	(2,948)	(1,074)
Cash flows from investing activities:
Capital expenditures	(3,277)	(3,027)
Cash paid for acquisition of intangible asset	(22)	(25)
Purchases of marketable securities	(79)	0
Maturities and sales of marketable securities	7,500	0
Net cash provided by (used in) investing activities	4,122	(3,052)
Cash flows from financing activities:
Repayments of long-term debt	0	(31)
Proceeds from stock options exercised and employee stock purchase plan	156	314
Repurchase of common stock	(390)	0
Payment of finance lease	(156)	(152)
Net cash (used in) provided by financing activities	(390)	131
Effect of exchange rate changes on cash and cash equivalents	(607)	204
Net increase (decrease) in cash and cash equivalents	177	(3,791)
Cash and cash equivalents at beginning of period	18,365	18,050
Cash and cash equivalents at end of period	18,542	14,259
Supplemental disclosure of non-cash investing activities:
Changes in accrued other and accounts payable related to property and equipment additions	$ 423	$ 161