Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash Flows From Operating Activities
Net loss	$ (7,375)	$ (10,856)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	3,309	3,143
Stock-based compensation expense	1,315	1,055
Deferred income taxes	26	26
(Gain) Loss on disposition of property and equipment and other assets	(15)	17
Changes in assets and liabilities:
Accounts receivable	(530)	174
Other receivables	871	(50)
Inventory	(5,734)	(5,122)
Prepaid expenses	(312)	(47)
Deposits	80	(110)
Other assets	14	15
Accounts payable	7,180	(284)
Deferred revenue	(209)	(152)
Accrued expenses	2,642	2,241
Net cash provided by (used in) operating activities	1,262	(9,950)
Cash Flows From Investing Activities
Proceeds from disposition of property, equipment	21	55
Payments for the purchase of property and equipment	(3,433)	(4,053)
Increase in restricted cash	(250)
Net cash used in investing activities	(3,662)	(3,998)
Cash Flows From Financing Activities
Proceeds from private placement, net		33,639
Proceeds from the exercise of stock options	671	1,296
Net cash provided by financing activities	671	34,935
Net (decrease) increase in cash and cash equivalents	(1,729)	20,987
Cash and cash equivalents:
Beginning of year	32,152	12,939
End of period	$ 30,423	$ 33,926