Schedule of Revenue and Percentages of Revenue Sales by Product Line (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation Of Revenue [Line Items]
Net revenue	$ 2,938	$ 8,645	$ 7,721	$ 18,971
Product Concentration Risk | Sales Revenue, Net
Disaggregation Of Revenue [Line Items]
Percentage of sales	100.00%	100.00%	100.00%	100.00%
Laser systems
Disaggregation Of Revenue [Line Items]
Net revenue	$ 1,091	$ 4,917	$ 3,142	$ 10,880
Laser systems | Product Concentration Risk | Sales Revenue, Net
Disaggregation Of Revenue [Line Items]
Percentage of sales	37.10%	56.90%	40.70%	57.40%
Imaging systems
Disaggregation Of Revenue [Line Items]
Net revenue		$ 63		$ 615
Imaging systems | Product Concentration Risk | Sales Revenue, Net
Disaggregation Of Revenue [Line Items]
Percentage of sales		0.70%	0.00%	3.20%
Consumables and other
Disaggregation Of Revenue [Line Items]
Net revenue	$ 862	$ 2,084	$ 2,334	$ 4,196
Consumables and other | Product Concentration Risk | Sales Revenue, Net
Disaggregation Of Revenue [Line Items]
Percentage of sales	29.30%	24.10%	30.20%	22.10%
Services
Disaggregation Of Revenue [Line Items]
Net revenue	$ 985	$ 1,578	$ 2,245	$ 3,273
Services | Product Concentration Risk | Sales Revenue, Net
Disaggregation Of Revenue [Line Items]
Percentage of sales	33.60%	18.30%	29.10%	17.30%
License fees and royalties
Disaggregation Of Revenue [Line Items]
Net revenue		$ 3		$ 7