计算机辅助光学设计code_V_S4节.pptVIP

Symptom is error message from the MTF option: Error message is issued because one or more rays in the edge row or column passes through the apertures, suggesting that the ray grid may be too small to fill the apertures. In this instance, lens drawing and footprint plot do not immediately reveal cause. ERROR - For field 1, wavelength 1, rays at the edge of the pupil may be ignored. Check apertures and vignetting for consistency. Weird Effects in MTF - Symptom Weird Effects in MTF - Diagnosis To diagnose, attempt to trace rays at the edge of the pupil grid. Methods: RSI (guessed pupil coordinate 1, e.g., RSI F1 0.0 1.3) Enlarge pupil (NAO in this example) and draw dense ray fan in VIE, e.g., nao 2*(nao);vie;fan yz 31;fld red n n;go The offending ray Can’t determine default apertures because reference rays aren’t traceable at larger NAO. Weird Effects in MTF - Remedy User had no apertures defined. Normally, default circular clear apertures would have prevented this, but user had set CA APE. Thus, the only aperture imposed was on the stop surface in the rear group. The problem ray had gross spherical aberration and was not blocked. REMEDY: Use CA YES. Other diffraction options such as PSF can give similar messages. Grid in MTF option is ~25% oversize. In other diffraction options it is 100% oversize, as determined by NRD/TGR. Default Apertures Near Images The default apertures are sized to pass the reference rays at the center and edges of the pupil. The assumption is that R2 through R5 are the outermost rays and are suitable for determining the appropriate size for an aperture. Near an intermediate or final image, aberrations may invalidate this assumption. Often happens in systems with a reticle, faceplate, or platen. Effects are at the outermost field only: Bogus image quality (may not be obvious) Low relative illumination (may be obvious) Default Apertures Near Images (cont’d.) The transverse aberration (RIM) plot may look innocuous, but actually ho