Income taxes, Deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets [Abstract]
Deferred Tax Assets, Operating Loss Carryforwards, Domestic	$ 0	$ 2,297
Foreign net operating losses	733	676
State net operating losses	84	149
Accrued severance	165	0
Capitalized R&D expenses	3,127	1,708
Inventory reserves	896	648
Deferred revenue	31	41
Warranty reserve	24	17
Stock compensation expense	790	769
Other accrued compensation	404	222
R&D credit carryforward	695	1,238
Other Assets	360	0
Other liabilities and reserves	0	463
Gross deferred tax assets	7,309	8,228
Valuation allowance	(719)	(656)
Net deferred tax assets	6,590	7,572
Deferred tax liabilities [Abstract]
Depreciation and amortization	237	196
Other	49	49
Net deferred tax liabilities	286	245
Total net deferred tax assets	$ 6,304	$ 7,327