Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($)	12 Months Ended
	Apr. 30, 2022	Apr. 30, 2021
Income Statement [Abstract]
Revenues	$ 48,296,000	$ 54,254,000
Cost of revenues	39,697,000	37,333,000
Gross margin	8,599,000	16,921,000
Selling and administrative expenses	11,662,000	13,189,000
Research and development expenses	4,975,000	4,690,000
Operating loss	(8,038,000)	(958,000)
Other income (expense):
Investment income	199,000	458,000
Loss on disposal of asset	(110,000)	0
Loss on impairment of Morion	(796,000)	0
Interest expense	(77,000)	(127,000)
Other income (expense), net	160,000	1,103,000
(Loss) income before provision (benefit) from income taxes	(8,662,000)	476,000
Provision (benefit) from income taxes	1,000	(204,000)
Net (loss) income	$ (8,663,000)	$ 680,000
Net (loss) income per common share:
Basic and diluted (loss) earnings per share (in Dollars per share)	$ (0.93)	$ 0.07
Weighted average shares outstanding:
Basic (in Shares)	9,265,934	9,177,537
Diluted (in Shares)	9,265,934	9,248,425
Consolidated Statements of Comprehensive Income (Loss)
Net (loss) income	$ (8,663,000)	$ 680,000
Unrealized loss on marketable securities:
Change in market value of marketable securities before reclassification, net of tax	(726,000)	(177,000)
Reclassification adjustment for realized gains included in net income, net of tax	(5,000)	(22,000)
Total unrealized loss on marketable securities, net of tax	(731,000)	(199,000)
Comprehensive (loss) income	$ (9,394,000)	$ 481,000