{"id":191,"date":"2018-04-18T15:25:18","date_gmt":"2018-04-18T13:25:18","guid":{"rendered":"http:\/\/www.parsum.de\/en\/?page_id=191"},"modified":"2018-04-18T15:31:10","modified_gmt":"2018-04-18T13:31:10","slug":"measuring-principle-fibre-optic-spatial-filter-method","status":"publish","type":"page","link":"https:\/\/www.parsum.de\/en\/particle-probes\/measuring-principle-fibre-optic-spatial-filter-method\/","title":{"rendered":"Measuring principle: Fibre-optic spatial filter method"},"content":{"rendered":"

[vc_row content_placement=”top” type=”vc_default” margin_top=”10″ margin_bottom=”25″ css=”.vc_custom_1508243052006{padding-top: 70px !important;}”][vc_column width=”2\/3″ css=”.vc_custom_1508243083034{padding-bottom: 30px !important;}” offset=”vc_col-lg-offset-0 vc_col-lg-6 vc_col-md-offset-0 vc_col-md-6 vc_col-sm-offset-2 vc_col-xs-12″][vc_column_text]Parsum probes use an optical method to measure the shadows of particles moving through a measuring gap at the tip of the probe.<\/p>\n

To this end, a collimated laser beam is shone through the measuring gap. Moving particles then create moving shadows on the opposite side of the measuring gap, on which there are two fibre-optic receivers for detecting the velocities and times of flight of the individual particles.<\/p>\n

The velocity sensor is a spatial frequency filter consisting of a linear grating arrangement of optical fibres, and the time-of-flight detector is a single optical fibre located after it. The geometric length of each individual particle shadow is then determined by combining the individual particle velocity with the individual time of flight of the particle, and is then stored in a dynamic ring buffer on an ongoing basis. The content of this adjustable-length buffer forms the basis for calculating the particle size and velocity distributions as well as the particle attributes \u2013 continuously, online and directly within the process.[\/vc_column_text][\/vc_column][vc_column width=”1\/3″ css=”.vc_custom_1508243072531{padding-bottom: 30px !important;}” offset=”vc_col-lg-offset-0 vc_col-lg-6 vc_col-md-offset-0 vc_col-md-6 vc_col-sm-offset-2 vc_col-xs-12″][vc_single_image image=”194″ img_size=”full” add_caption=”yes” onclick=”zoom” image_hovers=”false” lazy_loading=”true”][\/vc_column][\/vc_row][vc_row][vc_column][vc_separator style=”dashed” border_width=”3″][\/vc_column][\/vc_row][vc_row][vc_column]

Extended spatial frequency filter technique<\/h2><\/div>
<\/span><\/div><\/div>[vc_single_image image=”195″ img_size=”full” add_caption=”yes” alignment=”center” onclick=”zoom” image_hovers=”false” lazy_loading=”true”][\/vc_column][\/vc_row][vc_row][vc_column][vc_separator style=”dashed” border_width=”3″][\/vc_column][\/vc_row][vc_row content_placement=”top” type=”vc_default” margin_top=”10″ margin_bottom=”25″][vc_column width=”2\/3″ css=”.vc_custom_1508243083034{padding-bottom: 30px !important;}” offset=”vc_col-lg-offset-0 vc_col-lg-6 vc_col-md-offset-0 vc_col-md-6 vc_col-sm-offset-2 vc_col-xs-12″]

Particle velocity determination<\/h2><\/div>
<\/span><\/div><\/div>[vc_column_text]The fibre-optic spatial filtering method is a specific version of a spatial frequency filter in the form of a probe. It consists of a lattice arrangement of optical fibres on one side of the measuring volume, and a light source on the other side.<\/p>\n

This determines the time frequency of individual moving particles during the measuring operation. This is performed by projecting the particle movement onto the optical array, with a subsequent frequency analysis of the resulting signal. The velocity of the individual particle is calculated from the measured frequency and the known lattice constant of the array.<\/p>\n

[\/vc_column_text][\/vc_column][vc_column width=”1\/3″ css=”.vc_custom_1508243072531{padding-bottom: 30px !important;}” offset=”vc_col-lg-offset-0 vc_col-lg-6 vc_col-md-offset-0 vc_col-md-6 vc_col-sm-offset-2 vc_col-xs-12″][vc_single_image image=”65″ img_size=”full” add_caption=”yes” image_hovers=”false” lazy_loading=”true”][\/vc_column][\/vc_row][vc_row][vc_column][vc_separator style=”dashed” border_width=”3″][\/vc_column][\/vc_row][vc_row content_placement=”top” type=”vc_default” margin_top=”10″ margin_bottom=”25″ css=”.vc_custom_1508243052006{padding-top: 70px !important;}”][vc_column width=”2\/3″ css=”.vc_custom_1508243083034{padding-bottom: 30px !important;}” offset=”vc_col-lg-offset-0 vc_col-lg-6 vc_col-md-offset-0 vc_col-md-6 vc_col-sm-offset-2 vc_col-xs-12″]

Determining the particle time of flight<\/h2><\/div>
<\/span><\/div><\/div>[vc_column_text]<\/p>\n

Adding an optical pulse channel to the spatial filter makes it possible to determine the time of flight of a particle. The particle size in the direction of movement is obtained directly from the time of flight and the velocity.<\/p>\n

[\/vc_column_text][\/vc_column][vc_column width=”1\/3″ css=”.vc_custom_1508243072531{padding-bottom: 30px !important;}” offset=”vc_col-lg-offset-0 vc_col-lg-6 vc_col-md-offset-0 vc_col-md-6 vc_col-sm-offset-2 vc_col-xs-12″][vc_single_image image=”66″ img_size=”full” add_caption=”yes” image_hovers=”false” lazy_loading=”true”][\/vc_column][\/vc_row][vc_row][vc_column][vc_empty_space][\/vc_column][\/vc_row]<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

[vc_row content_placement=”top” type=”vc_default” margin_top=”10″ margin_bottom=”25″ css=”.vc_custom_1508243052006{padding-top: 70px !important;}”][vc_column width=”2\/3″ css=”.vc_custom_1508243083034{padding-bottom: 30px !important;}” offset=”vc_col-lg-offset-0 vc_col-lg-6 vc_col-md-offset-0 vc_col-md-6 vc_col-sm-offset-2 vc_col-xs-12″][vc_column_text]Parsum probes use an optical method to measure the shadows of particles moving through a measuring gap at the tip of the probe. To this end, a collimated laser beam is shone through the measuring gap. Moving particles…<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":45,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-191","page","type-page","status-publish","hentry","description-off"],"yoast_head":"\nMeasuring principle: Fibre-optic spatial filter method - Parsum EN<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.parsum.de\/en\/particle-probes\/measuring-principle-fibre-optic-spatial-filter-method\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Measuring principle: Fibre-optic spatial filter method - Parsum EN\" \/>\n<meta property=\"og:description\" content=\"[vc_row content_placement=”top” type=”vc_default” margin_top=”10″ margin_bottom=”25″ css=”.vc_custom_1508243052006{padding-top: 70px !important;}”][vc_column width=”2\/3″ css=”.vc_custom_1508243083034{padding-bottom: 30px !important;}” offset=”vc_col-lg-offset-0 vc_col-lg-6 vc_col-md-offset-0 vc_col-md-6 vc_col-sm-offset-2 vc_col-xs-12″][vc_column_text]Parsum probes use an optical method to measure the shadows of particles moving through a measuring gap at the tip of the probe. 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