Edge steepness vs transition width

Transition width and edge steepness for a LP02-785RU-25 U-grade RazorEdge® filter

Transition width and edge steepness are two terms often used to describe the spectral properties of edge filters and it is important to know that these two terms are related, but not interchangeable.

Transition Width is the maximum distance between the laser line (where OD>6) and the 50% transmission point.

Edge Steepness is the actual distance between the place where OD>6 ends and the 50% transmission point.

Transition width is the term most often used to specify filters in a catalog, as transition width allows the user to know exactly how far from the laser line he can expect to transmit light.  Edge steepness is a more effective term to describe how fast the filter transitions from blocking to transmission.  Please note that transition width is always greater than edge steepness.

 

Edge Filter Type Guaranteed Transition Width
(% of laser wavelength)
Typical Edge Steepness
(% of laser wavelength)
RazorEdge E-grade < 0.5% 0.2%
RazorEdge U-grade < 1.0% 0.5%
RazorEdge S-grade* < 2.0% 0.5%
EdgeBasic < 2.5% 1.5%

*RazorEdge S-Grade LWP and SWP have been discontinued.