Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash Flows from Operating Activities:
Net income	$ 3,803,818	$ 19,732
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,666,510	2,068,092
Bond premium amortization	18,637
Loss on disposal of fixed assets	73,226	45,409
Provision for doubtful accounts		13,158
Provision / write-off of excess and obsolete inventory	139,409	270,362
Provision for warranty	(35,944)	(98,221)
Stock-based compensation expense	758,054	962,917
Litigation judgment expense	(2,200,000)
Deferred income taxes	1,818,413	159,930
Provision for unrecognized tax benefits	12,368	1,282
Change in assets and liabilities:
Accounts receivable	(2,523,138)	1,925,549
Inventory	226,602	1,264,997
Prepaids and other assets	(524,842)	(1,201,733)
Accounts payable and accrued liabilities	100,483	(671,883)
Deferred revenue	225,409	(337,202)
Customer deposits	103,670	(65,675)
Net cash provided by operating activities	3,662,675	4,356,714
Cash Flows from Investing Activities:
Purchases of investments	(5,244,295)	(9,785,345)
Proceeds from maturity of investments	5,000,000
Purchases of property and equipment	(277,267)	(325,376)
Purchases of intangible assets	(122,541)	(87,856)
Net cash used by investing activities	(644,103)	(10,198,577)
Cash Flows from Financing Activities:
Repurchase of common stock		(5,061,649)
Proceeds from stock options exercised	14,629	3,923
Net cash provided (used) by financing activities	14,629	(5,057,726)
Effect of exchange rate change on cash and cash equivalents	15,649	26,948
Net increase (decrease) in cash and cash equivalents	3,048,850	(10,872,641)
Cash and cash equivalents, beginning of period	21,300,733	42,684,241
Cash and cash equivalents, end of period	24,349,583	31,811,600
Supplemental Disclosure:
Cash paid for income taxes - net	135,000	36,000
Non-Cash Transactions:
Property and equipment purchases in accounts payable	$ 107,488	$ 108,454