Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	May 31, 2023	May 31, 2022	May 31, 2021
Cash flows from operating activities:
Net loss	$ (52,442,000)	$ (26,547,000)	$ (31,548,000)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	30,873,000	29,349,000	25,916,000
Non-cash lease expense	2,484,000	2,439,000	2,456,000
Goodwill impairment	14,549,000	0	0
Stock based compensation	11,158,000	10,692,000	8,625,000
Change in fair value of contingent consideration	2,320,000	1,212,000	89,000
Deferred income tax provision	(2,311,000)	(3,708,000)	(4,805,000)
Changes in accounts receivable allowances	695,000	118,000	207,000
Asset impairments and disposals	291,000	391,000	14,228,000
Other	(513,000)	(93,000)	(147,000)
Changes in operating assets and liabilities:
Accounts receivable	(1,299,000)	(17,151,000)	(4,162,000)
Inventories	(8,198,000)	(2,796,000)	11,539,000
Prepaid expenses and other	332,000	(5,012,000)	(3,181,000)
Accounts payable, accrued and other liabilities	2,139,000	3,912,000	4,876,000
Net cash provided by (used in) operating activities	78,000	(7,194,000)	24,093,000
Cash flows from investing activities:
Additions to property, plant and equipment	(3,812,000)	(4,297,000)	(5,187,000)
Additions to placement and evaluation units	(5,394,000)	(11,410,000)	(8,524,000)
Cash paid for acquisitions	0	(3,600,000)	0
Acquisition of intangibles	(540,000)	0	0
Net cash used in investing activities	(9,746,000)	(19,307,000)	(13,711,000)
Cash flows from financing activities:
Proceeds from issuance of and borrowings on long-term debt	70,000,000	0	0
Repayment of long-term debt	(45,000,000)	0	(20,000,000)
Proceeds from borrowings on long-term debt	0	5,000,000	0
Deferred financing costs on long-term debt	(751,000)	0	0
Proceeds from exercise of stock options and employee stock purchase plan	1,171,000	2,683,000	3,014,000
Net cash provided by (used in) financing activities	25,420,000	7,683,000	(16,986,000)
Effect of exchange rate changes on cash and cash equivalents	43,000	(518,000)	330,000
Increase (decrease) in cash and cash equivalents	15,795,000	(19,336,000)	(6,274,000)
Cash and cash equivalents at beginning of year	28,825,000	48,161,000	54,435,000
Cash and cash equivalents at end of year	44,620,000	28,825,000	48,161,000
Supplemental disclosure of non-cash investing and financing activities:
Increase (decrease) in accounts payable for purchases of fixed assets	124,000	14,000	(139,000)
Cash paid during the year for:
Interest	2,577,000	562,000	731,000
Income taxes	$ 342,000	$ 329,000	$ 313,000