Specifying Optical Filters

The first step toward developing a successful design of any optical filter is having an understanding of the operating environment of the filter. Parameters such as angle-of-incidence, operating temperature, illumination source, and detector have a significant effect upon filter performance. The following is a description of all the important parameters associated with the specifications of Optical Filters:

Application

  • Description of Application
  • Instrument Requirements
  • Fluorophores (where applicable)

Spectral Requirements

  • Transmission requirement and region of interest
  • Reflection requirement and region of interest
  • OD Blocking requirement
  • Edge steepness
  • Edge placement

Optical Requirements

  • Surface Quality
  • Flatness (S1)
  • Flatness (S2)
  • Parallelism
  • Transmitted Wavefront

Operating Conditions

  • Operating Temperature
  • Storage Temperature
  • Humidity

Optical System

  • Angle of Incidence
  • Cone Half Angle
  • System Speed
  • Illumination Source
  • Detector
  • Polarization State

Substrate Requirements

  • Length and Tolerance
  • Width and Tolerance
  • Diameter and Tolerance
  • Thickness and Tolerance
  • Clear Aperture
  • Edge Treatments
    • Bevel
    • Edge Blackening
    • Filter Housing

Durability Requirements

  • Hardness
  • Adhesion
  • Humidity

Other Requirements

  • Part identification and marking/li>
  • Part Orientation
  • Packaging requirements
  • Packaging label requirements
  • Data correlation / Lot traceability