Disaggregation of Revenues, Geographic Sales and Product Sales - Net Sales by Geographic Areas (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Jan. 01, 2021	Oct. 02, 2020	Jul. 03, 2020	Apr. 03, 2020	Jan. 03, 2020	Sep. 27, 2019	Jun. 28, 2019	Mar. 29, 2019	Jan. 01, 2021	Jan. 03, 2020	Dec. 28, 2018
Geographic And Sales [Line Items]
Total net sales		$ 45,998	$ 47,081	$ 35,194	$ 35,187	$ 38,883	$ 39,055	$ 39,664	$ 32,583	$ 163,460	$ 150,185	$ 123,954
Geographic Distribution, Domestic [Member]
Geographic And Sales [Line Items]
Total net sales										6,158	8,106	7,316
Geographic Distribution, Foreign [Member]
Geographic And Sales [Line Items]
Total net sales										157,302	142,079	116,638
Geographic Distribution, Foreign [Member] | China [Member]
Geographic And Sales [Line Items]
Total net sales	[1]									71,692	64,820	46,070
Geographic Distribution, Foreign [Member] | JAPAN
Geographic And Sales [Line Items]
Total net sales										34,986	26,881	23,151
Geographic Distribution, Foreign [Member] | Other [Member]
Geographic And Sales [Line Items]
Total net sales	[2]									$ 50,624	$ 50,378	$ 47,417

[1] The China region includes sales into China and Hong Kong.  

[2] No other location individually exceeds 10% of the total net sales.