Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:
Net income	$ 1,894,976	$ 1,668,248
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation expense	284,177	260,675
Change in fair value of derivative instrument	92,993	95,053
Gain on disposition of long-term assets	(17,346)	(44,698)
Depreciation and amortization	1,268,398	1,157,203
Deferred income taxes	(143,404)	(501,066)
Excess tax benefit from employee stock plans	(5,026)	(19,065)
Changes in operating assets and liabilities:
Trade accounts receivable, net	1,792,262	(1,289,472)
Other receivables	(200,167)	44,376
Inventories	(1,083,782)	(376,087)
Prepaid income taxes	(27,340)	(222,501)
Prepaid expenses, other	61,852	(52,585)
Accounts payable	(685,522)	535,795
Compensation and related expenses	(226,313)	(244,823)
Other accrued expenses	(4,306)	42,775
Accrued product warranties	(103,600)	1,556
Accrued income taxes	171,214	318,831
Deferred revenue	822,472	462,373
Net cash provided by operating activities	3,891,538	1,836,588
Cash flows from investing activities:
Proceeds from maturities of marketable securities	205,000	3,290,278
Purchases of property, plant and equipment	(831,938)	(1,056,502)
Proceeds from sale of property and equipment	55,923	115,898
Cash paid for patents and other intangible assets	(143,842)	(417,417)
Other	(1,497)	(1,506)
Net cash provided by (used in) investing activities	(716,354)	1,930,751
Cash flows from financing activities:
Proceeds from the revolving lines of credit	12,885,854	3,724,773
Payments on the revolving lines of credit	(12,298,923)	(4,628,237)
Payments on notes payable and seller financed note payable	(1,349,248)	(1,316,669)
Proceeds from the exercise of stock options	179,508	246,617
Excess tax benefit from employee stock plans	5,026	19,065
Dividends paid	(1,242,222)	(1,187,957)
Net cash used in financing activities	(1,820,005)	(3,142,408)
Effect of exchange rate changes on cash and cash equivalents	(34,746)	(115,625)
Net increase in cash and cash equivalents	1,320,433	509,306
Cash and cash equivalents:
Beginning of period	4,132,953	2,415,416
End of period	5,453,386	2,924,722
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	800,413	717,570
Cash paid during the period for interest	113,305	169,839
Supplemental schedule of noncash investing and financing activities:
Dividends accrued	622,856	610,251
Purchases of prepaid expenses, fixed assets and intangibles in accounts payable	$ 238,664	$ 86,068