CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Jan. 01, 2021	Jan. 03, 2020	Dec. 28, 2018
Cash flows from operating activities:
Net income	$ 5,913,000	$ 14,048,000	$ 4,968,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property, plant, and equipment	3,060,000	3,665,000	2,430,000
Amortization of intangibles	35,000	34,000	34,000
Deferred income taxes	(849,000)	(3,481,000)	441,000
Change in net pension liability	656,000	359,000	231,000
Loss on disposal of property and equipment	213,000	14,000	10,000
Stock-based compensation expense	12,146,000	10,547,000	6,762,000
Provision for sales returns and bad debts	835,000	275,000	905,000
Inventory provision	1,706,000	1,580,000	1,473,000
Changes in working capital:
Accounts receivable	(3,974,000)	(4,502,000)	(6,040,000)
Inventories	(1,390,000)	(950,000)	(4,194,000)
Prepayments, deposits, and other current assets	(3,753,000)	(1,313,000)	(598,000)
Accounts payable	(812,000)	1,084,000	243,000
Other current liabilities	7,165,000	4,435,000	6,102,000
Net cash provided by operating activities	20,951,000	25,795,000	12,767,000
Cash flows from investing activities:
Acquisition of property and equipment	(8,404,000)	(10,095,000)	(2,245,000)
Acquisition of patents and licenses		(83,000)
Net cash used in investing activities	(8,404,000)	(10,178,000)	(2,245,000)
Cash flows from financing activities:
Proceeds from public offering of stock			72,150,000
Repayment of finance lease obligations	(561,000)	(1,294,000)	(1,907,000)
Repayment on line of credit	(515,000)	(2,018,000)	(747,000)
Repurchase of employee common stock for taxes withheld			(54,000)
Proceeds from the exercise of stock options	20,646,000	3,459,000	5,195,000
Proceeds from vested restricted stock	1,000	2,000	2,000
Net cash provided by financing activities	19,571,000	149,000	74,639,000
Effect of exchange rate changes on cash, cash equivalents and restricted cash	367,000	203,000	197,000
Increase in cash, cash equivalents and restricted cash	32,485,000	15,969,000	85,358,000
Cash, cash equivalents and restricted cash, at beginning of year	119,968,000	103,999,000	18,641,000
Cash, cash equivalents and restricted cash, at end of year	$ 152,453,000	$ 119,968,000	$ 103,999,000