CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands		12 Months Ended
		Jan. 03, 2020	Dec. 28, 2018	Dec. 29, 2017
Income Statement [Abstract]
Net sales		$ 150,185,000	$ 123,954,000	$ 90,611,000
Cost of sales		38,231,000	32,444,000	26,331,000
Gross profit		111,954,000	91,510,000	64,280,000
Selling, general and administrative expenses:
General and administrative		29,313,000	24,287,000	19,465,000
Marketing and selling		45,491,000	38,600,000	28,402,000
Research and development		25,298,000	22,028,000	20,044,000
Total selling, general and administrative expenses		100,102,000	84,915,000	67,911,000
Operating income (loss)		11,852,000	6,595,000	(3,631,000)
Other income (expense), net:
Interest income (expense), net		988,000	165,000	(112,000)
Gain (loss) on foreign currency transactions	[1]	(517,000)	(836,000)	819,000
Royalty income		551,000	633,000	581,000
Other income, net		152,000	82,000	47,000
Total other income, net		1,174,000	44,000	1,335,000
Income (loss) before income taxes		13,026,000	6,639,000	(2,296,000)
Provision (benefit) for income taxes		(1,022,000)	1,671,000	(157,000)
Net income (loss)		$ 14,048,000	$ 4,968,000	$ (2,139,000)
Net income (loss) per share:
Basic		$ 0.32	$ 0.12	$ (0.05)
Diluted		$ 0.30	$ 0.11	$ (0.05)
Weighted average shares outstanding:
Basic		44,493	42,587	41,004
Diluted		46,895	45,257	41,004

[1] Shown as a separate line item on the Consolidated Statements of Operations.