Summary of Significant Accounting Policies - Additional Information (Details)			1 Months Ended	12 Months Ended
	Dec. 22, 2017	Dec. 21, 2017	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) shares	Sep. 30, 2018 USD ($) shares	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019 GBP (£)	Sep. 30, 2019 USD ($)	Oct. 01, 2018 USD ($)
Significant Accounting Policies [Line Items]
Research and Development Expense				$ 626,000	$ 823,000
Cash, FDIC Insured Amount									$ 250,000
Operating Costs and Expenses				16,062,000	14,892,000
Other Research and Development Expense			$ 35,000
Patent Costs				300,000	400,000
Advertising Expense				$ 143,000	$ 145,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares				95,602	160,537
Cash, Uninsured Amount			2,000,000		$ 2,000,000				100,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	35.00%		21.00%	24.28%
Asset Impairment Charges				$ 0	$ 182,000
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount				700,000
Deferred Revenue, Revenue Recognized				$ 253,000
Impact of Restatement on Opening Retained Earnings, Net of Tax										$ 22,000
Revenue, Performance Obligation, Description of Payment Terms				cost-plus contracts, the customer generally pays during the performance period for 80%-90% of the actual costs incurred.
Innovation and Development Segment [Member]
Significant Accounting Policies [Line Items]
Revenue, Remaining Performance Obligation, Amount									37,500,000
Optics [Member]
Significant Accounting Policies [Line Items]
Operating Costs and Expenses				$ 7,853,000	7,003,000
Asset Impairment Charges				0	0
Revenue, Remaining Performance Obligation, Amount									7,200,000
Scenario, Forecast [Member] | Innovation and Development Segment [Member]
Significant Accounting Policies [Line Items]
Revenue, Remaining Performance Obligation, Percentage						35.00%	39.00%
Scenario, Forecast [Member] | Optics [Member]
Significant Accounting Policies [Line Items]
Revenue, Remaining Performance Obligation, Percentage						18.00%	82.00%
Shipping and Handling [Member]
Significant Accounting Policies [Line Items]
Operating Costs and Expenses				$ 31,000	40,000
Accounts Receivable [Member] | Geographic Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Accounts Receivable, Net			1,724,000		$ 1,724,000				$ 1,145,000
Concentration Risk, Percentage				26.00%	40.00%
Radiation Monitoring Devices Inc [Member]
Significant Accounting Policies [Line Items]
Research and Development Expense				$ 12,400,000	$ 9,900,000
Other Research and Development Expense				$ 600,000	800,000
Xcede Technologies, Inc [Member]
Significant Accounting Policies [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent								63.00%	63.00%
Finite-Lived Patents, Gross			$ 100,000		100,000				$ 0
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				21.00%
Asset Impairment Charges					$ 200,000
Xcede Technologies, Inc [Member] | Common Stock Owned By Others [Member]
Significant Accounting Policies [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent								17.00%	17.00%
Dynasil Biomedical [Member]
Significant Accounting Policies [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent								83.00%	83.00%
Maximum [Member] | Acquired Customer Based [Member]
Significant Accounting Policies [Line Items]
Finite-Lived Intangible Asset, Useful Life				20 years	20 years
Minimum [Member] | Acquired Customer Based [Member]
Significant Accounting Policies [Line Items]
Finite-Lived Intangible Asset, Useful Life				5 years	5 years
Transportation Equipment [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life				5 years
Building and Building Improvements [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life				25 years
Building and Building Improvements [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life				8 years
Machinery and Equipment [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life				20 years
Machinery and Equipment [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life				5 years
Office furniture and fixtures [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life				10 years
Office furniture and fixtures [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life				5 years
Hilger Crystals Ltd [Member]
Significant Accounting Policies [Line Items]
Cash, FDIC Insured Amount | £								£ 75,000