Note 6 - Revenue From Contracts with Customers - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net revenues	$ 21,097	$ 15,888	$ 39,968	$ 30,068
Semiconductor Market [Member]
Net revenues	13,043	10,155	23,582	20,594
Industrial Market [Member]
Net revenues	5,000	2,178	10,653	2,298
Telecommunications Market [Member]
Net revenues	1,343	2,196	2,622	4,891
Other Non-semiconductors Markets [Member]
Net revenues	1,711	1,359	3,111	2,285
Thermal Testing Products [Member]
Net revenues	6,389	6,312	12,420	13,134
Induction Heating Products [Member]
Net revenues	5,937	1,725	11,559	1,725
Semiconductor Production Test Products [Member]
Net revenues	6,809	6,053	12,148	12,216
Service and Other Products [Member]
Net revenues	1,962	1,798	3,841	2,993
End User [Member]
Net revenues	18,173	15,029	34,502	27,515
OEM and Integrators [Member]
Net revenues	$ 2,924	$ 859	$ 5,466	$ 2,553