CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Net sales	$ 11,739	$ 8,508	$ 28,594	$ 23,710
Cost of sales	7,354	5,298	18,138	14,855
Gross profit	4,385	3,210	10,456	8,855
Operating expenses:
Selling expenses	136	161	415	438
General and administrative expenses	1,280	725	2,922	2,052
Research and development costs	1,104	620	3,184	1,501
Total operating expenses	2,520	1,506	6,521	3,991
Operating income	1,865	1,704	3,935	4,864
Interest expense	(102)	(58)	(231)	(180)
Interest and other income	41	9	102	77
Gain on sale of investments	783		795
Income before income taxes	2,587	1,655	4,601	4,761
Income tax expense	(592)	(442)	(1,004)	(1,194)
Net income	1,995	1,213	3,597	3,567
Other comprehensive income (loss), net of tax:
Unrealized income (loss) from marketable equity investments	136	(1,262)	1,442	(613)
Comprehensive income (loss)	$ 2,131	$ (49)	$ 5,039	$ 2,954
Basic net income per share:
Net income	$ 0.52	$ 0.31	$ 0.94	$ 0.90
Diluted net income per share:
Net income	$ 0.50	$ 0.30	$ 0.90	$ 0.88
Weighted average common shares outstanding:
Basic	3,817	3,871	3,843	3,944
Diluted	3,966	3,999	3,998	4,071
Common shares outstanding	3,701	3,837	3,701	3,837