Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 29, 2019	8,331
Balance at Dec. 29, 2019	$ 8	$ 297,073	$ (283,258)	$ 13,823
Common stock issued under stock plans and employee stock purchase plans (in shares)	121
Common stock issued under stock plans and employee stock purchase plans	$ 0	(24)	0	(24)
Stock Issued During Period, Shares, New Issues (in shares)	2,642
Common stock offering, net of issuance costs	$ 3	8,097	0	8,100
Stock-based compensation	0	1,739	0	1,739
Net loss	$ 0	0	(11,151)	(11,151)
Balance (in shares) at Jan. 03, 2021	11,094
Balance at Jan. 03, 2021	$ 11	306,885	(294,409)	12,487
Common stock issued under stock plans and employee stock purchase plans (in shares)	571
Common stock issued under stock plans and employee stock purchase plans	$ 0	(222)	0	(222)
Stock Issued During Period, Shares, New Issues (in shares)	198
Common stock offering, net of issuance costs	$ 1	1,033	0	1,034
Stock-based compensation	0	2,526	0	2,526
Net loss	$ 0	0	(6,616)	(6,616)
Balance (in shares) at Jan. 02, 2022	11,863
Balance at Jan. 02, 2022	$ 12	310,222	(301,025)	9,209
Common stock issued under stock plans and employee stock purchase plans (in shares)	542
Common stock issued under stock plans and employee stock purchase plans	$ 0	253	0	253
Stock Issued During Period, Shares, New Issues (in shares)	797
Common stock offering, net of issuance costs	$ 1	4,664	0	4,665
Stock-based compensation	0	2,035	0	2,035
Net loss	$ 0	0	(4,267)	(4,267)
Balance (in shares) at Jan. 01, 2023	13,202
Balance at Jan. 01, 2023	$ 13	$ 317,174	$ (305,292)	$ 11,895