Summary of Significant Accounting Policies (Revenue by Product) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 33,530	$ 27,266	$ 23,850	$ 25,482	$ 24,300	$ 17,219	$ 21,745	$ 24,001	$ 110,128	$ 87,265	$ 85,617
Navigation And Inertial Sensing [Member]
Disaggregation of Revenue [Line Items]
Revenue									38,983	23,203	7,149
Defense Optoelectronics [Member]
Disaggregation of Revenue [Line Items]
Revenue									16,257	9,883	6,418
CA TV Lasers And Transmitters [Member]
Disaggregation of Revenue [Line Items]
Revenue									44,457	41,150	62,000
Chips [Member]
Disaggregation of Revenue [Line Items]
Revenue									4,873	10,828	$ 10,050
Other Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue									$ 5,558	$ 2,201
Revenue From Products And Services Transferred Over Time Risk | Revenue Benchmark
Disaggregation of Revenue [Line Items]
Concentration risk percentage									100.00%	100.00%	100.00%
Revenue From Products And Services Transferred Over Time Risk | Revenue Benchmark | Navigation And Inertial Sensing [Member]
Disaggregation of Revenue [Line Items]
Concentration risk percentage									35.00%	27.00%	8.00%
Revenue From Products And Services Transferred Over Time Risk | Revenue Benchmark | Defense Optoelectronics [Member]
Disaggregation of Revenue [Line Items]
Concentration risk percentage									15.00%	11.00%	8.00%
Revenue From Products And Services Transferred Over Time Risk | Revenue Benchmark | CA TV Lasers And Transmitters [Member]
Disaggregation of Revenue [Line Items]
Concentration risk percentage									40.00%	47.00%	72.00%
Revenue From Products And Services Transferred Over Time Risk | Revenue Benchmark | Chips [Member]
Disaggregation of Revenue [Line Items]
Concentration risk percentage									5.00%	12.00%	12.00%
Revenue From Products And Services Transferred Over Time Risk | Revenue Benchmark | Other Revenue [Member]
Disaggregation of Revenue [Line Items]
Concentration risk percentage									5.00%	3.00%