Concentrations - Summary of Net Revenue from Various Products (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Concentration Risk [Line Items]
Net revenue	$ 10,326	$ 10,020
Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Percentage of sales	100.00%	100.00%
Laser systems
Concentration Risk [Line Items]
Net revenue	$ 5,964	$ 5,703
Laser systems | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Percentage of sales	57.80%	57.00%
Imaging systems
Concentration Risk [Line Items]
Net revenue	$ 552	$ 583
Imaging systems | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Percentage of sales	5.30%	5.80%
Consumables and other
Concentration Risk [Line Items]
Net revenue	$ 2,112	$ 2,034
Consumables and other | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Percentage of sales	20.50%	20.30%
Services
Concentration Risk [Line Items]
Net revenue	$ 1,695	$ 1,697
Services | Product Concentration Risk | Sales Revenue, Net
Concentration Risk [Line Items]
Percentage of sales	16.40%	16.90%
License fees and royalties
Concentration Risk [Line Items]
Net revenue	$ 3	$ 3