CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income	$ 866,601	$ 820,673
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation expense	132,108	123,537
Change in fair value of derivative instrument	107,266
(Gain) loss on disposition of long-term assets	3,700	(37,440)
Depreciation and amortization	558,783	166,400
Deferred income taxes	(190,623)	31,211
Excess tax benefit from employee stock plans	(2,224)	(43,945)
Changes in operating assets and liabilities:
Trade accounts receivable, net	195,343	(284,097)
Other receivables	96,929	(2,389)
Inventories	26,789	(109,598)
Prepaid income taxes	(152,763)	(78,233)
Prepaid expenses, other	(129,855)	(262,032)
Accounts payable	(909,326)	547,874
Compensation and related expenses	(395,795)	(739,583)
Other accrued expenses	5,587	5,266
Accrued product warranties	7,977	(26,894)
Accrued income taxes	221,694	54,737
Deferred revenue	313,188	(367,190)
Net cash provided by (used in) operating activities	755,379	(201,703)
Cash flows from investing activities:
Purchases of marketable securities		(365,000)
Proceeds from maturities of marketable securities	2,203,586	1,473,804
Purchases of property, plant and equipment	(58,769)	(617,238)
Proceeds from sale of property and equipment		82,266
Cash paid for patents and other intangible assets	(178,462)	(190,819)
Other	(753)	(826)
Net cash provided by investing activities	1,965,602	382,187
Cash flows from financing activities:
Proceeds from the revolving lines of credit	1,008,389	4,000,000
Payments on the revolving lines of credit	(1,725,000)
Proceeds from term note payable		3,500,000
Payments on notes payable and seller financed note payable	(222,555)
Proceeds from the exercise of stock options	102,690	267,213
Excess tax benefit from employee stock plans	2,224	43,945
Dividends paid	(579,534)	(544,156)
Net cash provided by (used in) financing activities	(1,413,786)	7,267,002
Effect of exchange rate changes on cash and cash equivalents	(245,654)	109,558
Net increase in cash and cash equivalents	1,061,541	7,557,044
Cash and cash equivalents:
Beginning of period	2,415,416	8,425,846
End of period	3,476,957	15,982,890
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	382,136	486,992
Cash paid during the period for interest	63,735
Supplemental schedule of noncash investing and financing activities:
Dividends accrued	608,038	574,654
Purchases of fixed assets and intangibles in accounts payable	$ 343,486	$ 156,383