Consolidated Statements Of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 1,312,000	$ 11,562,000	$ (2,089,000)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	2,285,000	2,086,000	1,968,000
Provision for (recovery of) doubtful accounts	(48,000)	24,000	(44,000)
Deferred taxes	(297,000)	(5,269,000)	38,000
Foreign currency transaction losses (gains)	115,000	(341,000)	(225,000)
Stock-based compensation	895,000	863,000	511,000
Changes in operating assets and liabilities:
Accounts receivable	171,000	(2,769,000)	(161,000)
Inventories	(3,163,000)	1,029,000	(2,489,000)
Other assets	(31,000)	(346,000)	(24,000)
Accounts payable	(2,100,000)	550,000	1,146,000
Advance customer payments	62,000	(153,000)	(9,000)
Accrued expenses	(1,627,000)	1,888,000	(1,011,000)
Net cash provided by (used in) operating activities	(2,426,000)	9,124,000	(2,389,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities of available-for-sale marketable securities	6,931,000	4,690,000	5,167,000
Proceeds from sales of available-for-sale marketable securities	0	1,502,000	1,518,000
Purchases of available-for-sale marketable securities	(7,475,000)	(8,127,000)	(4,934,000)
Additions to equipment and leasehold improvements	(1,226,000)	(1,363,000)	(691,000)
Additions to patents	(120,000)	(71,000)	(106,000)
Net cash provided by (used in) investing activities	(1,890,000)	(3,369,000)	954,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	378,000	474,000	458,000
Tax payments related to shares withheld for share-based compensation plans	(35,000)	(9,000)	0
Common stock repurchases	(240,000)	0	0
Proceeds from issuance of common stock under employee stock purchase plan	258,000	181,000	178,000
Net cash provided by financing activities	361,000	646,000	636,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Effects of exchange rate changes on cash and cash equivalents	259,000	(35,000)	(98,000)
Net increase (decrease) in cash and cash equivalents	(3,696,000)	6,366,000	(897,000)
Cash and cash equivalents – beginning of period	10,640,000	4,274,000	5,171,000
Cash and cash equivalents – end of period	$ 6,944,000	$ 10,640,000	$ 4,274,000