Comparison of Absorptive ND Filter and Reflective ND Filter
Feature	Reflective ND Filter	Absorptive ND Filter
Attenuation Mechanism	Reflective	Absorptive
Thermal Effect	Low (no heat from reflected light)	High (absorption of light into heat)
Damage Threshold	Higher (for high power lasers)	Lower (may be damaged by overheating)
Spectral Neutrality	Excellent (dependent on coating process)	Good (adulterated materials may have slight color deviation)
Angular Sensitivity	Higher (large angle of incidence may change OD value)	Lower
Cost	Higher	Lower

What are the considerations for choosing a reflective neutral density filter?
Power Tolerance:
Confirmation of laser wavelength and power density (e.g. CO₂ lasers require ZnSe substrates).
Dielectric ND filters typically withstand >1 kW/cm² (pulsed lasers require additional consideration of peak power).

Stray Light Treatment:
Reflected light needs to be directed in a harmless direction (e.g. beam traps).

Spectral Range:
Ultraviolet (UV) or infrared (IR) bands require special coatings (e.g. UV fused silica substrate).