Concentrations - Summary of Net Revenue from Various Products (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Concentration Risk [Line Items]
Net revenue	$ 10,020	$ 10,874
Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	100.00%	100.00%
Laser systems
Concentration Risk [Line Items]
Net revenue	$ 5,703	$ 6,729
Laser systems | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	57.00%	61.90%
Imaging systems
Concentration Risk [Line Items]
Net revenue	$ 583	$ 626
Imaging systems | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	5.80%	5.70%
Consumables and other
Concentration Risk [Line Items]
Net revenue	$ 2,034	$ 1,692
Consumables and other | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	20.30%	15.60%
Services
Concentration Risk [Line Items]
Net revenue	$ 1,697	$ 1,795
Services | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	16.90%	16.50%
License fees and royalties
Concentration Risk [Line Items]
Net revenue	$ 3	$ 32
License fees and royalties | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Concentration Risk Percentage	0.00%	0.30%