Annual report [Section 13 and 15(d), not S-K Item 405]

Note 1 - Summary of Significant Accounting Policies (Details Textual)

v3.25.3
Note 1 - Summary of Significant Accounting Policies (Details Textual)
 12 Months Ended
Sep. 30, 2025
USD ($)
$ / shares
shares
Sep. 30, 2024
USD ($)
$ / shares
shares
Sep. 30, 2023
USD ($)
shares
May 07, 2024
USD ($)
Apr. 29, 2024
USD ($)
Accounts Receivable, Allowance for Credit Loss, Current | $ $ 0   $ 79,000    
Depreciation | $ 3,920,000 $ 4,528,000 3,623,000    
Goodwill, Impairment Loss | $ $ 0 0 0    
Number of Patents Granted 63        
Amortization of Intangible Assets | $ $ 219,400 1,380,000 970,000    
Impairment, Long-Lived Asset, Held-for-Use | $ 0 0 $ 0    
Unrecognized Tax Benefits | $ $ 0 $ 0      
Stock Repurchased During Period, Shares | shares 17,497 15,879 12,862    
Common Stock, Shares Authorized | shares 50,000,000 50,000,000      
Common Stock, Par or Stated Value Per Share (in dollars per share) | $ / shares $ 0.01 $ 0.01      
Preferred Stock, Shares Authorized | shares 500,000 500,000      
Preferred Stock, Shares Issued | shares 0 0      
Preferred Stock, Shares Outstanding | shares 0 0      
Research and Development Expense | $ $ 2,422,000 $ 3,000,000 $ 3,115,000    
Advertising Expense | $ $ 355,000 $ 464,000 $ 554,000    
Share-Based Payment Arrangement, Option [Member]          
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares 366,118 364,104 243,749    
Performance Shares [Member]          
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares 50,747        
Undesignated Shares [Member]          
Preferred Stock, Shares Authorized | shares 5,000,000        
Series B Preferred Stock [Member]          
Preferred Stock, Shares Authorized | shares 500,000        
Preferred Stock, Shares Issued | shares 0        
Preferred Stock, Shares Outstanding | shares 0        
Share Repurchase Program [Member]          
Share Repurchase Program, Authorized, Amount | $ $ 65,000,000       $ 40,000,000
Stock Repurchase Program [Member]          
Share Repurchase Program, Authorized, Amount | $       $ 65,000,000  
Stock Repurchased During Period, Shares | shares 550,766        
Stock Repurchased During Period, Value | $ $ 16,530,000        
Stock Repurchased, Cumulative | shares 2,280,546        
Stock Repurchased, Value, Cumulative | $ $ 56,607,000        
Share Repurchase Program, Remaining Authorized, Amount | $ $ 8,393,000