https://pfspipe.ipmu.jp/jira This file is an XML representation of an issue en-us 8.3.4 803005 13-09-2019 https://pfspipe.ipmu.jp/jira/browse/PIPE2D-508 DRP 2-D Pipeline <p>At the moment `frd_sigma` parameter in the 2d psf_model takes values which are not connected with actual values for the frd (focal ratio degradation). The values that seem to fit the data are around 0.05 to 0.1, but it is not clear what values of frd these numbers actually are. This is because I never made sure that `frd_sigma` corresponds to some realistic values of frd. The task here it to figure how how are values of `frd_sigma` connected with actual values of frd. </p> PIPE2D-508

Find out translation from real frd to `frd_sigma` parameter 2d psf_model

Task Normal Done Done Brent Belland ncaplar Mon, 27 Jan 2020 14:21:41 +0000 Mon, 4 Jan 2021 20:23:12 +0000 Mon, 31 Aug 2020 22:48:08 +0000 0 2 <p>It appears to me that we can convert from frd_sigma if we know the f number of the input beam light. In the code, frd_sigma is just the fraction of an image length corresponding to the convolution (with a factor of sqrt(2) due to.how scipy.special.erf works). If effective_illum_radius as passed to the code represents the fraction of the image length that the pupil image takes up, then the ratio of frd_sigma/effective_illum_radius is the conversion factor between the angular size of the pupil image and the angular size of the FRD (i.e., the 'actual' value of FRD). I believe that generally f/2.8 is used in the fibers (though you have the correct values for each individual measurement), corresponding to a numerical aperture of 0.17857 (=1/<span class="error">&#91;2*2.8&#93;</span>).</p> <p> </p> <p>It's simplistic, but I think in general "actual" frd in radians = (Numerical Aperture)*sqrt(2)*frd_sigma/(effective_illum_radius).</p> <p> </p> <p>As a sanity check, if effective_illum_radius ~ 1 and frd_sigma~0.05-0.1, then for f/2.8 the frd ranges from 12.6 milliradians to 25 milliradians, which sounds a little high but reasonable depending on the experimental setup.</p> <p> </p> <p>I'll follow up with lab data to verify.</p> <p>FRD is incorporated into all analysis up to this point and in the foreseeable future with this equation.</p> Relates PIPE2D-509 Development Rank 0|02qprx:ii Sprint 2DDRP-2021 A Story Points 2.0