Segment, Customer and Geographical Reporting - Segment reporting information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2018
Segment Reporting Information [Line Items]
Revenue	$ 11,090,000	$ 10,542,000	$ 32,650,000	$ 29,985,000
Gross profit	$ 4,106,000	$ 4,175,000	$ 12,156,000	$ 11,659,000
GM %	37.00%	40.00%	37.00%	39.00%
Operating expenses	$ 4,252,000	$ 3,565,000	$ 12,103,000	$ 11,175,000
Operating income (loss)	(146,000)	610,000	53,000	484,000
Depreciation and amortization	363,000	317,000	1,056,000	927,000
Capital expenditures	119,000	803,000	679,000	1,853,000
Intangibles, net	665,000	959,000	665,000	959,000	$ 755,000
Goodwill	5,864,000	5,907,000	5,864,000	5,907,000	5,900,000
Total assets	32,090,000	29,642,000	32,090,000	29,642,000	$ 31,532,000
Optics [Member]
Segment Reporting Information [Line Items]
Revenue	5,899,000	6,159,000	17,846,000	17,011,000
Gross profit	$ 2,112,000	$ 2,299,000	$ 6,121,000	$ 6,038,000
GM %	36.00%	37.00%	34.00%	35.00%
Operating expenses	$ 2,237,000	$ 1,721,000	$ 5,993,000	$ 5,154,000
Operating income (loss)	(125,000)	578,000	128,000	884,000
Depreciation and amortization	297,000	261,000	863,000	738,000
Capital expenditures	90,000	707,000	586,000	1,635,000
Intangibles, net	334,000	408,000	334,000	408,000
Goodwill	925,000	968,000	925,000	968,000
Total assets	21,084,000	21,117,000	21,084,000	21,117,000
Innovation and Development [Member]
Segment Reporting Information [Line Items]
Revenue	5,191,000	4,383,000	14,804,000	12,974,000
Gross profit	$ 1,994,000	$ 1,876,000	$ 6,035,000	$ 5,621,000
GM %	38.00%	43.00%	41.00%	43.00%
Operating expenses	$ 1,992,000	$ 1,760,000	$ 6,012,000	$ 5,297,000
Operating income (loss)	2,000	116,000	23,000	324,000
Depreciation and amortization	63,000	53,000	183,000	179,000
Capital expenditures	29,000	76,000	93,000	153,000
Intangibles, net	136,000	171,000	136,000	171,000
Goodwill	4,939,000	4,939,000	4,939,000	4,939,000
Total assets	10,805,000	8,018,000	10,805,000	8,018,000
Biomedical [Member]
Segment Reporting Information [Line Items]
Revenue	0	0	0	0
Gross profit	$ 0	$ 0	$ 0	$ 0
GM %	0.00%	0.00%	0.00%	0.00%
Operating expenses	$ 23,000	$ 84,000	$ 98,000	$ 724,000
Operating income (loss)	(23,000)	(84,000)	(98,000)	(724,000)
Depreciation and amortization	3,000	3,000	10,000	10,000
Capital expenditures	0	20,000	0	65,000
Intangibles, net	195,000	380,000	195,000	380,000
Goodwill	0	0	0	0
Total assets	$ 201,000	$ 507,000	$ 201,000	$ 507,000