Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 12,948	$ 19,514
Securities available-for-sale	9,230	7,679
Accounts receivable, net	6,412	6,329
Inventories, net	4,693	4,979
Other current assets	596	642
Restricted cash	244	244
Total current assets	34,123	39,387
Property and equipment, net	4,469	4,693
Intangible assets, net	461	584
Goodwill	184	184
Other assets	82	61
Total assets	39,319	44,909
Liabilities and stockholders' equity
Accounts payable	1,816	1,546
Accrued compensation	2,536	2,364
Accrued warranty	203	326
Deferred revenue	1,655	1,849
Other accrued liabilities	1,985	2,199
Total current liabilities	8,195	8,284
Other liabilities	295	176
Total liabilities	8,490	8,460
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.0001 par value: 10,000,000 shares authorized; no shares issued or outstanding	0	0
Common stock, $0.0001 par value: 80,000,000 shares authorized; 18,194,323 and 19,144,448 shares issued and outstanding (net of treasury shares) at June 30, 2013 and December 31, 2012, respectively	2	2
Treasury stock, at cost; 2,334,400 and 1,073,641 shares at March 31, 2013 and December 31, 2012, respectively	(5,121)	(2,086)
Additional paid-in capital	157,142	156,634
Accumulated other comprehensive income (loss)	(41)	17
Accumulated deficit	(121,153)	(118,118)
Total stockholders' equity	30,829	36,449
Total liabilities and stockholders' equity	$ 39,319	$ 44,909