{"id":247,"date":"2023-06-08T09:53:38","date_gmt":"2023-06-08T07:53:38","guid":{"rendered":"https:\/\/logbooks.ifosim.org\/finesse\/?p=247"},"modified":"2023-06-08T09:53:38","modified_gmt":"2023-06-08T07:53:38","slug":"simulating-the-mirror-clipping-losses-in-finesse3","status":"publish","type":"post","link":"https:\/\/logbooks.ifosim.org\/finesse\/2023\/06\/08\/simulating-the-mirror-clipping-losses-in-finesse3\/","title":{"rendered":"Simulating the mirror clipping losses in FINESSE3"},"content":{"rendered":"\n

The BS mirror in LIGO is considered not large enough. Therefore, Hiro mentioned that there was a calculation long time ago about the clipping loss at BS. The calculation was done with OSCAR and FINESSE, however, different result was found. So we want to use these simulation tools to do these calculation again.<\/p>\n\n\n\n

On my side, I am doing the FINESSE part. In FINESSE, we will need to use a phase map to apply a clear aperture. The way to create this phase map is<\/p>\n\n\n\n

# create the aperture map for PR\/SR\/Input\/End\ndiameter_m = 0.33\nradius_m = diameter_m \/ 2\nx_m = y_m = np.linspace(-radius_m, radius_m, 200)\nsmap_m = Map(\n            x_m,\n            y_m,\n            amplitude=circular_aperture(x_m, y_m, radius_m, x_offset=0.0, y_offset=0.0),\n        )<\/code><\/pre>\n\n\n\n
Then we use the following code to apply the created phase map to a mirror using the following code<\/p>\n\n\n\n
localvirgo.model.PR.surface_map = smap_m\nlocalvirgo.model.SR.surface_map = smap_m\nlocalvirgo.model.NI.surface_map = smap_m\nlocalvirgo.model.NE.surface_map = smap_m\nlocalvirgo.model.WI.surface_map = smap_m\nlocalvirgo.model.WE.surface_map = smap_m<\/code><\/pre>\n\n\n\n
For BS, the phase map should be applied in a different way since there is an incident angle. A elliptical aperture is created using the following code<\/p>\n\n\n\n
def elliptical_aperture(x, y, R_ap, ang, x_offset=0, y_offset=0):\n    #x,y,R_ap is diameter in meter\n    m_ang = ang\/180*np.pi\n    X = np.linspace(-x\/2, x\/2, 200)\n    Y = np.linspace(-y\/2, y\/2, 200)\n    xv, yv = np.meshgrid(X, Y)\n    R = np.sqrt((xv\/np.sin(m_ang)) ** 2 + (yv) ** 2)\n    m = np.ones_like(xv)\n    m[R > R_ap\/2] = 0\n    return X,Y,m<\/code><\/pre>\n\n\n\n
This code returns three arrays, the first one is X axis, the second one is Y axis, the third one is the map with 1 inside the aperture and 0 outside the aperture. To test this function, we run the following code<\/p>\n\n\n\n
import matplotlib.pyplot as plt\nfrom matplotlib import cbook\nfrom matplotlib import cm\nimport colorcet as cc\nfrom matplotlib.colors import LightSource\nm = elliptical_aperture(0.55, 0.55, 0.55, 45)\nfig, ax = plt.subplots(1, figsize=(8,8), dpi=100)\nc = ax.pcolormesh(m[0], m[1], m[2], cmap=cc.cm.diverging_bwr_20_95_c54)\ncbar = fig.colorbar(c, ax=ax)\ncbar.set_label(r'Normalized spectrum density [A.U.]', fontsize=16)<\/code><\/pre>\n\n\n\n
\"\"<\/figure>\n\n\n\n
To apply this phase map to mirror, we did the following<\/p>\n\n\n\n
# create the aperture map for BS\ndiameter_bs = 0.55\nang_bs = 45\nradius_bs = diameter_bs \/ 2\nx_bs = y_bs = np.linspace(-radius_bs, radius_bs, 200)\nsmap_bs = Map(\n            x_bs,\n            y_bs,\n            amplitude=elliptical_aperture(diameter_m, diameter_bs, diameter_bs, ang_bs, x_offset=0.0, y_offset=0.0)[2],\n        )\n\n# apply to BS front surface\nlocalvirgo.model.lpr_yu.surface_map = smap_bs\n# apply to BS back surface\nlocalvirgo.model.lsr_yu.surface_map = smap_bs<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
The BS mirror in LIGO is considered not large enough. Therefore, Hiro mentioned that there was a calculation long time ago about the clipping loss at BS. The calculation was done with OSCAR and FINESSE, however, different result was found. So we want to use these simulation tools to do these calculation again. On my […]<\/p>\n","protected":false},"author":91,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ssl_alp_hide_revisions":false,"footnotes":"","ssl_alp_hide_crossreferences_to":false},"categories":[1],"tags":[],"ssl-alp-coauthor":[65],"class_list":["post-247","post","type-post","status-publish","format-standard","hentry","category-uncategorised"],"_links":{"self":[{"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/posts\/247","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/users\/91"}],"replies":[{"embeddable":true,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/comments?post=247"}],"version-history":[{"count":3,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/posts\/247\/revisions"}],"predecessor-version":[{"id":252,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/posts\/247\/revisions\/252"}],"wp:attachment":[{"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/media?parent=247"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/categories?post=247"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/tags?post=247"},{"taxonomy":"ssl-alp-coauthor","embeddable":true,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/ssl-alp-coauthor?post=247"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}