Revenue - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue recognized, previously included in customer advances and deferred revenue	$ 0.4	$ 1.2

Contract With Customer, Liability, Revenue Recognized During Period

No definition available.

Name:	lasr_ContractWithCustomerLiabilityRevenueRecognizedDuringPeriod
Namespace Prefix:	lasr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration