CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Sep. 27, 2024	Sep. 29, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net (loss) income	$ (47,200,000)	$ 48,700,000	$ 30,800,000
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Share-based compensation expense	15,300,000	13,500,000	14,000,000.0
Depreciation	21,200,000	19,500,000	19,000,000.0
Amortization of intangible assets	9,900,000	13,700,000	14,600,000
Deferred taxes	37,000,000.0	(39,500,000)	600,000
Loss from equity method investments	2,000,000.0	1,600,000	2,600,000
Impairment of equity method investment	0	16,400,000	0
Amortization of deferred loan costs	2,800,000	2,600,000	10,900,000
Gain on purchase of business	(2,100,000)	0	0
Inventory write-down	4,900,000	5,600,000	6,400,000
Loss on operating lease abandonment	0	0	1,900,000
Other, net	1,500,000	3,000,000.0	4,100,000
Changes in assets and liabilities:
Accounts receivable	6,700,000	9,800,000	(18,100,000)
Inventories	6,600,000	20,200,000	(85,000,000.0)
Prepaid expenses and other assets	3,300,000	7,000,000.0	10,300,000
Accounts payable	(3,200,000)	(15,000,000.0)	19,700,000
Accrued liabilities and other current and long-term liabilities	(9,100,000)	(1,000,000.0)	(14,900,000)
Deferred revenues	(2,300,000)	2,300,000	0
Net cash provided by operating activities	47,300,000	108,400,000	16,900,000
Cash flows from investing activities:
Purchases of property, plant and equipment	(26,900,000)	(20,700,000)	(21,300,000)
Loss on settlement of cash flow hedge	0	(200,000)	(500,000)
Proceeds from maturities of marketable debt securities	58,800,000	28,300,000	2,000,000.0
Purchase of marketable debt securities	(56,600,000)	(52,200,000)	(18,700,000)
Purchase of marketable equity securities	(200,000)	(2,700,000)	(2,400,000)
Purchase of certificates of deposit	(4,200,000)	(1,000,000.0)	(7,200,000)
Proceeds from maturities of certificates of deposit	1,800,000	0	0
Acquisitions of businesses, net of cash acquired	900,000	(1,000,000.0)	0
Settlement of net investment hedge	0	7,000,000.0	0
Proceeds from sales of business and assets	0	0	1,700,000
Investments in and loans to privately-held companies	0	0	(600,000)
Other	(1,100,000)	(2,400,000)	(1,400,000)
Net cash used in investing activities	(27,500,000)	(44,900,000)	(48,400,000)
Cash flows from financing activities:
Repayments of borrowings	(1,600,000)	(2,400,000)	(29,400,000)
Payment of debt issuance costs	(2,300,000)	0	0
Proceeds from shares issued under employee stock purchase plan	3,800,000	3,900,000	4,900,000
Proceeds from exercise of stock options	0	200,000	3,800,000
Taxes related to net share settlement of equity awards	(2,200,000)	(1,400,000)	(2,800,000)
Other financing activities	(1,000,000.0)	(500,000)	(300,000)
Net cash used in financing activities	(3,300,000)	(200,000)	(23,800,000)
Effects of exchange rate changes on cash and cash equivalents and restricted cash	(100,000)	100,000	(200,000)
Net increase (decrease) in cash and cash equivalents and restricted cash	16,400,000	63,400,000	(55,500,000)
Cash and cash equivalents and restricted cash at beginning of period	154,000,000.0	90,600,000	146,100,000
Cash and cash equivalents and restricted cash at end of period	170,400,000	154,000,000.0	90,600,000
Supplemental cash flow information:
Cash paid for interest	27,600,000	27,400,000	29,500,000
Cash paid for income tax, net of refunds	20,200,000	16,700,000	2,200,000
Supplemental non-cash activities:
Purchases of property, plant and equipment financed through accounts payable	$ 1,000,000.0	$ 2,700,000	$ 1,500,000