Consolidated Statements Of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 5,742,000	$ 774,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,629,000	2,832,000
Non-cash operating lease expense	521,000	828,000
(Recovery) provision for doubtful accounts	(20,000)	8,000
Deferred taxes	366,000	393,000
Foreign currency transaction (gains) losses	(97,000)	127,000
Share-based compensation	1,181,000	991,000
Unrealized loss on available for sale equity security	18,000	12,000
Gain on sale of equipment	0	(26,000)
Changes in operating assets and liabilities:
Accounts and trade notes receivable	1,888,000	(1,170,000)
Inventories	(5,212,000)	(439,000)
Prepaid expenses and other assets	49,000	539,000
Accounts payable	(1,903,000)	(1,529,000)
Advance customer payments and other	247,000	(49,000)
Accrued expenses	1,321,000	(856,000)
Operating lease liabilities	(772,000)	(308,000)
Net cash provided by operating activities	5,958,000	2,127,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities of available-for-sale marketable securities	11,576,000	7,835,000
Purchases of available-for-sale marketable securities	(13,186,000)	(12,033,000)
Proceeds from sale of equipment	0	84,000
Additions to equipment and leasehold improvements	(1,527,000)	(1,301,000)
Additions to patents	(212,000)	(150,000)
Net cash used in investing activities	(3,349,000)	(5,565,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	358,000	248,000
Tax payments related to shares withheld for share-based compensation plans	(605,000)	(67,000)
Common stock repurchases	0	(353,000)
Proceeds from issuance of common stock under employee stock purchase plan	224,000	203,000
Net cash (used in) provided by financing activities	(23,000)	31,000
Effects of exchange rate changes on cash and cash equivalents	(23,000)	(5,000)
Net increase (decrease) in cash and cash equivalents	2,563,000	(3,412,000)
Cash and cash equivalents – beginning of period	5,836,000	9,248,000
Cash and cash equivalents – end of period	$ 8,399,000	$ 5,836,000