illuminancen.

/ɪˈl(j)uːmɪnəns/

Etymology: < Latin illūmin-āntem (see illuminant adj. and n.) + -ance suffix.

Optics.

The amount of luminous flux per unit area; = illumination n. 1b.

ΘΚΠ

the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun]

brightness1674

self-luminosity1841

illumination1863

luminosity1898

illuminance1943

luminance1950

irradiance1956

1943 D. H. Jacobs Fund. Optical Engin. iv. 66 We have derived equations that give the illumination (or illuminance) only at points on the axis of the system.

1949 H. Margenau et al. Physics Princ. & Applic. xliv. 621 Illuminance is expressed in lumens/ft² (foot candles) or lumens/m² (luxes).

1955 R. C. Brown Textbk. Physics IV. l. 902 The illumination (sometimes called ‘intensity of illumination’ and also illuminance) of a surface is defined as the luminous flux incident per unit area on the surface.

1961 F. W. Weymouth in Hirsch & Wick Vision Aging Patient iv. 41 Since the extent of dark adaptation is..curtailed with age, the performance at low levels of illuminance begins to decline even before the age of 40 years.

1970 Nature 24 Jan. 347/2 Each pattern..was projected.. at an average screen illuminance of 3 millilamberts.

This entry has not yet been fully updated (first published 1976; most recently modified version published online March 2018).

单词	illuminance
释义	illuminancen. /ɪˈl(j)uːmɪnəns/ Etymology: < Latin illūmin-āntem (see illuminant adj. and n.) + -ance suffix. Optics. The amount of luminous flux per unit area; = illumination n. 1b. ΘΚΠ the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] brightness1674 self-luminosity1841 illumination1863 luminosity1898 illuminance1943 luminance1950 irradiance1956 1943 D. H. Jacobs Fund. Optical Engin. iv. 66 We have derived equations that give the illumination (or illuminance) only at points on the axis of the system. 1949 H. Margenau et al. Physics Princ. & Applic. xliv. 621 Illuminance is expressed in lumens/ft² (foot candles) or lumens/m² (luxes). 1955 R. C. Brown Textbk. Physics IV. l. 902 The illumination (sometimes called ‘intensity of illumination’ and also illuminance) of a surface is defined as the luminous flux incident per unit area on the surface. 1961 F. W. Weymouth in Hirsch & Wick Vision Aging Patient iv. 41 Since the extent of dark adaptation is..curtailed with age, the performance at low levels of illuminance begins to decline even before the age of 40 years. 1970 Nature 24 Jan. 347/2 Each pattern..was projected.. at an average screen illuminance of 3 millilamberts. This entry has not yet been fully updated (first published 1976; most recently modified version published online March 2018). < n.1943
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