Note 4 - Detail of Certain Asset Accounts (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 26, 2014	Dec. 27, 2013	Dec. 26, 2014	Dec. 27, 2013	Mar. 31, 2014
Note 4 - Detail of Certain Asset Accounts (Details) [Line Items]
Amortization of Intangible Assets	$ 153,000	$ 260,000	$ 539,000	$ 769,000
Finite-Lived Intangible Assets, Gross	15,736,000		15,736,000		15,461,000
Patents [Member] | Minimum [Member]
Note 4 - Detail of Certain Asset Accounts (Details) [Line Items]
Finite-Lived Intangible Asset, Useful Life			2 years
Patents [Member] | Maximum [Member]
Note 4 - Detail of Certain Asset Accounts (Details) [Line Items]
Finite-Lived Intangible Asset, Useful Life			20 years
Patents [Member]
Note 4 - Detail of Certain Asset Accounts (Details) [Line Items]
Finite-Lived Intangible Asset, Useful Life			10 years		10 years
Finite-Lived Intangible Assets, Gross	1,449,000		1,449,000		1,108,000
Other Intangible Assets [Member]
Note 4 - Detail of Certain Asset Accounts (Details) [Line Items]
Finite-Lived Intangible Assets, Gross	$ 729,000		$ 729,000		$ 795,000