Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Accounts receivable, due to allowance for doubtful accounts	$ 185	$ 221
Inventories	1,633	1,335
Operating loss carryforwards	5,179	4,443
Stock-based compensation expense	666	881
Property and equipment, due to difference in depreciation	68	283
Research and development tax credit carryforwards	5,852	5,743
Foreign tax credit carryforwards	2,345	2,345
State tax credit carryforwards	3,378	3,710
Capitalized research and development	5,354	5,003
Warranty reserve	177	302
Accrued expenses	640	1,206
Lease liability	215	483
Gross deferred tax assets	25,692	25,955
Less valuation allowance	(21,835)	(21,711)
Total deferred tax assets	3,857	4,244
Deferred tax liabilities:
Purchased intangible assets	0	(39)
Property and equipment, due to differences in depreciation	(3,386)	(3,514)
Right of use asset	(216)	(487)
Total deferred tax liabilities	(3,602)	(4,040)
Net deferred tax asset	255	204
Deferred income tax asset	256	259
Deferred income tax liability	$ (1)	$ (55)