Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net income (loss)	$ 6,953	$ (6,416)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization expense	1,989	3,313
Stock-based compensation expense	1,825	1,846
Provision adjustments related to credit loss	(52)	111
Provision adjustments related to product warranty	222	100
Gain (loss) on disposal of property, plant and equipment	189	(1,917)
Other	(292)	(100)
Total non-cash adjustments	3,881	3,353
Changes in operating assets and liabilities:
Accounts receivable and contract assets	(3,574)	(2,353)
Inventory	(3,909)	522
Other assets	1,121	(13,803)
Accounts payable	(660)	498
Accrued expenses and other current liabilities	(2,040)	11,081
Total change in operating assets and liabilities	(9,062)	(4,055)
Net cash provided by (used in) operating activities	1,772	(7,118)
Cash flows from investing activities:
Purchase of equipment	(1,142)	(2,418)
Proceeds from disposal of property, plant and equipment	583	14,904
Net cash (used in) provided by investing activities	(559)	12,486
Cash flows from financing activities:
Net payments on credit facilities	0	(5,497)
Proceeds from employee stock purchase plan and equity awards	428	281
Proceeds from sale of common stock	35,937	0
Issuance cost associated with sale of common stock	(2,796)	0
Taxes paid related to net share settlement of equity awards	(83)	(47)
Net cash provided by (used in) financing activities	33,486	(5,263)
Effect of exchange rate changes provided by foreign currency	44	8
Net increase in cash, cash equivalents and restricted cash	34,743	113
Cash, cash equivalents and restricted cash at beginning of period	30,538	21,977
Cash, cash equivalents and restricted cash at end of period	65,281	22,090
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid during the period for interest	31	83
Cash paid during the period for income taxes	295	59
NON-CASH INVESTING AND FINANCING ACTIVITIES
Changes in accounts payable related to purchases of equipment	$ (256)	$ (762)