Bench, Nodal, Test (Historical)
Wednesday, August 30, 2006
Geometric lens measurement in the past consisted of Nodal Bench Testing mainly resolution testing and contrast testing.
Nodal Bench Testing is performed on a Nodal Bench or Lens Bench. Nodal Bench Testing is the measurement of the first order and higher order properties of a lens and of the image that the lens forms. The Nodal Bench Testing parameters include:
Effective Focal Length
F Number
Back Local length
Distortion: radial; grid
Field Curvature: sagittal; tangential
Spherical Curvature: coma; astigmatism
Longitudinal Color and Lateral Color
Magnification
Vignetting
Object to Image Distance
Nodal Point Separation
Blur Spot Size and Blur Spot Pattern (Established techniques for examining Blur Spot pattern reveal many pertinent properties of the a lens; decentered components, tilted components, and aberrations present in the lens system.)
Nodal Bench testing is a non-interferometric metrology technique, which utilizes direct analysis of the image (visual interpretation) rather than wavefront analysis. Nodal Bench testing has been replaced completely by interferometer measurements. 
Source: “Geometric lens measurement” by Peter Carellas and Stephen Fatone, Photonics Spectra, August 1989
Reference: None Available
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posted by JD52 @ 8:16 PM,
