CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 809,000	$ 5,476,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	1,659,000	1,520,000
Provision for doubtful accounts	(15,000)	10,000
Deferred taxes	(27,000)	15,000
Foreign currency transaction losses (gains)	139,000	(66,000)
Stock based compensation	640,000	694,000
Changes in operating assets and liabilities:
Accounts receivable	(1,022,000)	(4,022,000)
Inventories	(5,260,000)	1,169,000
Other assets	(133,000)	(303,000)
Accounts payable	866,000	(304,000)
Advance customer payments	(3,000)	(26,000)
Accrued expenses	(1,906,000)	1,467,000
Net cash provided by (used in) operating activities	(4,253,000)	5,630,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities of available-for-sale marketable securities	5,187,000	3,571,000
Proceeds from sales of available-for-sale marketable securities	0	1,402,000
Purchases of available-for-sale marketable securities	(5,604,000)	(6,923,000)
Additions to equipment and leasehold improvements	(851,000)	(994,000)
Additions to patents	(107,000)	(59,000)
Net cash used in investing activities	(1,375,000)	(3,003,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	330,000	425,000
Proceeds from issuance of common stock under Employee Stock Purchase Plan	258,000	181,000
Net cash provided by financing activities	588,000	606,000
Effects of exchange rate changes on cash and cash equivalents	(7,000)	9,000
Net increase (decrease) in cash and cash equivalents	(5,047,000)	3,242,000
Cash and cash equivalents – beginning of period	10,640,000	4,274,000
Cash and cash equivalents – end of period	$ 5,593,000	$ 7,516,000