Statements of Income (Unaudited) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue
Revenue	$ 4,380,785	$ 6,501,945	$ 8,970,047	$ 12,796,641
Cost of sales	941,287	1,346,098	1,777,709	2,438,135
Gross profit	3,439,498	5,155,847	7,192,338	10,358,506
Expenses
Research and development	815,965	926,596	1,696,948	1,899,663
Selling, general, and administrative	358,182	368,450	713,193	698,459
Total expenses	1,174,147	1,295,046	2,410,141	2,598,122
Income from operations	2,265,351	3,860,801	4,782,197	7,760,384
Interest income	401,392	456,309	800,604	915,348
Income before taxes	2,666,743	4,317,110	5,582,801	8,675,732
Provision for income taxes	444,403	495,048	948,596	1,246,251
Net income	$ 2,222,340	$ 3,822,062	$ 4,634,205	$ 7,429,481
Net income per share – basic (in dollars per share)	$ 0.46	$ 0.79	$ 0.96	$ 1.53
Net income per share – diluted (in dollars per share)	0.46	0.79	0.96	1.53
Cash dividends declared per common share (in dollars per share)	$ 1	$ 1	$ 2	$ 2
Weighted average shares outstanding
Basic (in shares)	4,834,709	4,846,010	4,834,872	4,846,010
Diluted (in shares)	4,834,809	4,847,881	4,834,986	4,849,357
Product [Member]
Revenue
Revenue	$ 4,159,173	$ 6,187,708	$ 8,517,808	$ 12,273,072
Contract Research and Development [Member]
Revenue
Revenue	$ 221,612	$ 314,237	$ 452,239	$ 523,569