Note 2 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Accounts Receivable, Credit Loss Expense (Reversal)	$ 0	$ 3
Number of Operating Segments	2
Number of Reportable Segments	2
Inventory Write-down	$ 444	391
Depreciation, Total	630	685
Deferred Grant Proceeds	27
Foreign Currency Transaction Gain (Loss), before Tax, Total	(26)	$ (3)
City of Rochester and State of New York [Member]
Contingent Liability, Repayment of State and Local Grant Funds Received	463
Covenant, Future Amount Receivable	$ 423
Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	1 year
Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	10 years