CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 1,668,248	$ 678,514
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation expense	260,675	234,383
Change in fair value of derivative instrument	95,053
Gain on disposition of long-term assets	(44,698)	(22,948)
Depreciation and amortization	1,157,203	728,192
Deferred income taxes	(501,066)	(317,584)
Excess tax benefit from employee stock plans	(19,065)	(47,241)
Changes in operating assets and liabilities:
Trade accounts receivable, net	(1,289,472)	(261,163)
Other receivables	44,376	41,155
Inventories	(376,087)	1,139,422
Prepaid income taxes	(222,501)
Prepaid expenses, other	(52,585)	(355,297)
Accounts payable	535,795	91,253
Compensation and related expenses	(244,823)	(681,834)
Other accrued expenses	42,775	(291,603)
Accrued product warranties	1,556	(38,661)
Accrued income taxes	318,831	(422,843)
Deferred revenue	462,373	(460,093)
Net cash provided by operating activities	1,836,588	13,652
Cash flows from investing activities:
Purchases of marketable securities		(365,000)
Proceeds from maturities of marketable securities	3,290,278	1,605,442
Purchases of property, plant and equipment	(1,056,502)	(914,460)
Proceeds from sale of property and equipment	115,898	84,758
Payment for purchase of Dansensor, net of cash acquired		(12,764,429)
Cash paid for patents and other intangible assets	(417,417)	(130,640)
Other	(1,506)	(1,598)
Net cash provided by (used in) investing activities	1,930,751	(12,485,927)
Cash flows from financing activities:
Proceeds from the revolving lines of credit	3,724,773	5,100,000
Payments on the revolving lines of credit	(4,628,237)	(500,000)
Proceeds from term note payable		3,500,000
Payments on notes payable and seller financed note payable	(1,316,669)	(1,272,841)
Proceeds from the exercise of stock options	246,617	292,747
Excess tax benefit from employee stock plans	19,065	47,241
Dividends paid	(1,187,957)	(1,118,853)
Net cash provided by (used in) financing activities	(3,142,408)	6,048,294
Effect of exchange rate changes on cash and cash equivalents	(115,625)	(206,680)
Net increase (decrease) in cash and cash equivalents	509,306	(6,630,661)
Cash and cash equivalents:
Beginning of period	2,415,416	8,425,846
End of period	2,924,722	1,795,185
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	717,570	1,201,439
Cash paid during the period for interest	169,839	34,871
Supplemental schedule of noncash investing and financing activities:
Dividends accrued	610,251	574,938
Purchases of fixed assets and intangibles in accounts payable	86,068	60,147
Seller financed note payable for the acquisition of Dansensor		6,267,487
The Company purchased all of the common shares of Dansensor for $20,081,600 on April 2, 2012. The reconciliation of cash paid and liabilities assumed is as follows:
Fair value of assets acquired		26,938,817
Liabilities assumed		(6,857,217)
Net acquired assets		20,081,600
Seller financed note payable		(6,484,413)
Cash acquired		(832,758)
Payment for purchase of Dansensor, net of cash acquired and seller financed note payable		$ 12,764,429