Concentrations - Summary of Net Revenue from Various Products (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Concentration Risk [Line Items]
Net revenue	$ 46,926	$ 51,810	$ 48,475
Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	100.00%	100.00%	100.00%
Laser systems
Concentration Risk [Line Items]
Net revenue	$ 29,121	$ 35,150	$ 32,691
Laser systems | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	62.00%	67.90%	67.50%
Imaging systems
Concentration Risk [Line Items]
Net revenue	$ 3,685	$ 3,066	$ 2,237
Imaging systems | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	7.90%	5.90%	4.60%
Consumables and other
Concentration Risk [Line Items]
Net revenue	$ 7,332	$ 6,906	$ 6,877
Consumables and other | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	15.60%	13.30%	14.20%
Services
Concentration Risk [Line Items]
Net revenue	$ 6,660	$ 6,539	$ 6,465
Services | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	14.20%	12.60%	13.30%
License fees and royalties
Concentration Risk [Line Items]
Net revenue	$ 128	$ 149	$ 205
License fees and royalties | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	0.30%	0.30%	0.40%