Balance Sheets - USD ($)	Mar. 31, 2017	Mar. 31, 2016
Current assets
Cash and cash equivalents	$ 8,199,364	$ 7,534,593
Marketable securities, short-term	19,591,833	19,697,384
Accounts receivable, net of allowance for uncollectible accounts of $15,000	3,436,802	2,244,086
Inventories	3,358,298	3,205,233
Prepaid expenses and other assets	607,283	734,524
Total current assets	35,193,580	33,415,820
Fixed assets
Machinery and equipment	9,007,455	8,840,033
Leasehold improvements	1,644,419	1,539,965
	10,651,874	10,379,998
Less accumulated depreciation and amortization	9,238,626	8,688,285
Net fixed assets	1,413,248	1,691,713
Long-term deferred tax assets	357,055	51,188
Marketable securities, long-term	56,810,923	65,695,335
Total assets	93,774,806	100,854,056
Current liabilities
Accounts payable	376,275	317,990
Accrued payroll and other	576,313	556,674
Deferred revenue	142,733	714,805
Total current liabilities	1,095,321	1,589,469
Shareholders’ equity
Common stock, $0.01 par value, 6,000,000 shares authorized; 4,841,010 issued and outstanding as of March 31, 2017 and 4,835,010 issued and outstanding as of March 31, 2016	48,410	48,350
Additional paid-in capital	19,507,348	19,205,682
Accumulated other comprehensive (loss) income	(38,298)	451,359
Retained earnings	73,162,025	79,559,196
Total shareholders’ equity	92,679,485	99,264,587
Total liabilities and shareholders’ equity	$ 93,774,806	$ 100,854,056

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Name:	us-gaap_AccountsPayableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.