Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income (loss)	$ 25,643	$ (7,000)	$ (35,984)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization expense	4,061	5,484	7,142
Stock-based compensation expense	4,180	3,517	2,607
Provision adjustments related to doubtful accounts	33	188	62
Provision adjustments related to product warranty	322	373	186
Loss (gain) on disposal of property, plant and equipment	515	(2,284)	(302)
Other	(658)	(342)	464
Total non-cash adjustments	8,453	6,936	10,159
Changes in operating assets and liabilities:
Accounts receivable and contract assets	(5,348)	(7,518)	3,980
Inventory	(6,326)	(1,226)	6,486
Other assets	(1,500)	(13,465)	(238)
Accounts payable	(420)	6,171	(4,539)
Accrued expenses and other current liabilities	(9,349)	12,210	4,985
Total change in operating assets and liabilities	(22,943)	(3,828)	10,674
Net cash provided by (used) in operating activities	11,153	(3,892)	(15,151)
Cash flows from investing activities:
Purchase of equipment	(5,358)	(4,516)	(10,790)
Acquisition of business, net of cash acquired	0	0	(21,483)
Proceeds from future sale of assets	834	0	0
Proceeds from disposal of property, plant and equipment	687	15,403	470
Net cash (used in) provided by investing activities	(3,837)	10,887	(31,803)
Cash flows from financing activities:
Proceeds from PPP Loan	0	6,488	0
Net (payments) proceeds from borrowings of credit facilities	0	(5,497)	5,497
Proceeds from employee stock purchase plans and exercise of equity awards	844	619	505
Proceeds from sale of common stock	35,937	0	0
Issuance cost associated with sale of common stock	(2,796)	0	0
Taxes paid related to net share settlement of equity awards	(260)	(111)	(203)
Net cash provided by financing activities	33,725	1,499	5,799
Effect of exchange rate changes provided by foreign currency	103	67	(63)
Net increase (decrease) in cash, cash equivalents and restricted cash	41,144	8,561	(41,218)
Cash, cash equivalents and restricted cash at beginning of period	30,538	21,977	63,195
Cash, cash equivalents and restricted cash at end of period	71,682	30,538	21,977
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid during the period for interest	61	113	126
Cash paid during the period for income taxes	975	63	68
NON-CASH INVESTING AND FINANCING ACTIVITIES
Changes in accounts payable related to purchases of equipment	360	(520)	(180)
Restricted stock units issued in settlement of bonus	$ 0	$ 410	$ 0