Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Balance at Jan. 02, 2011	$ 29,313	$ 38	$ 186,304	$ 616	$ (157,645)
Balance (in shares) at Jan. 02, 2011		37,806
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under stock plans and employee stock purchase plans, shares		830
Common stock issued under stock plans and employee stock purchase plans, value	2,046	1	2,045
Change in unrealized gain on available-for-sale securities	(503)			(503)
Stock-based compensation	1,676		1,676
Net income (loss)	(7,594)				(7,594)
Balance at Jan. 01, 2012	24,938	39	190,025	113	(165,239)
Balance (in shares) at Jan. 01, 2012		38,636
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under stock plans and employee stock purchase plans, shares		748
Common stock issued under stock plans and employee stock purchase plans, value	1,148	1	1,147
Private stock Offering, net of issuance costs and warrants, shares		5,122
Private stock Offering, net issuance costs and warrants, value	9,345	5	9,340
Issuance of common stocks warrants, value	2,236		2,236
Change in unrealized gain on available-for-sale securities	(124)			(124)
Stock-based compensation	2,049		2,049
Net income (loss)	(12,314)				(12,314)
Balance at Dec. 30, 2012	27,278	45	204,797	(11)	(177,553)
Balance (in shares) at Dec. 30, 2012		44,506
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued under stock plans and employee stock purchase plans, shares		542
Common stock issued under stock plans and employee stock purchase plans, value	966	1	965
Private stock Offering, net of issuance costs and warrants, shares		8,740
Private stock Offering, net issuance costs and warrants, value	23,126	8	23,118
Issuance of common stocks warrants, value	0
Change in unrealized gain on available-for-sale securities	11			11
Stock-based compensation	1,493		1,493
Net income (loss)	(12,276)				(12,276)
Balance at Dec. 29, 2013	$ 40,598	$ 54	$ 230,373	$ 0	$ (189,829)
Balance (in shares) at Dec. 29, 2013		53,788