1916 L. T. Troland in Trans. Illuminating Engin. Soc. (U.S.) 11 950 I have..found it very convenient to express all intensity measures in terms of a unit of retinal illumination which I have called the photon.

1929 Bureau of Standards Jrnl. Res. (U.S.) 2 445 If the rods initiate the nerve activity responsible for the blue arcs a pure spectral stimulus of wave length, say, 640 mμ, would have to be at a much higher illumination (measured in photons..) than a stimulus of wave length less than, say 550 mμ.

1949 J. H. Prince Visual Devel. I. vi. 85 Feldman..has estimated that, whereas a rod requires only 0·00025 photons to stimulate it, a cone requires 0·025 photons.

1953 H. H. Emsley Visual Optics (ed. 5) II. xviii. 232 A surface of luminance one millilambert observed through a 4 mm. diameter pupil gives a retinal illumination of 2·5 × 4² = 40 photons.

1921 J. Joly in Proc. Royal Soc. B. 92 226 In the foregoing pages..the unit light stimulus discharged by a single visual fibre is frequently referred to. It represents a very small amount of energy... It must not be confused with the quantum of energy... I propose to designate it a photon.

1921 J. Joly in Proc. Royal Soc. B. 92 228 The stimulus value of the three colour sensations in such proportions as to give white light is nine photons.

1926 G. N. Lewis in Nature 18 Dec. 874/1 I therefore take the liberty of proposing for this hypothetical new atom, which is not light but plays an essential part in every process of radiation, the name photon.

1929 Jrnl. Amer. Chem. Soc. 51 2850 In 1906, Einstein showed that the photo-electric effect and many photochemical reactions could be explained in terms of the Quantum Theory if light itself consisted of discrete particles of energy or quanta, now usually called photons.

1942 J. D. Stranathan ‘Particles’ of Mod. Physics viii. 357 One would expect the disintegration to be followed by the radiation of a γ-ray photon.

1968 M. S. Livingston Particle Physics v. 96 In particle physics, the individual photons entering or emerging from interactions are treated as particles with zero rest mass, velocity c, energy E = hv, and momentum p = E/c.

1970 J. B. Birks Photophysics of Aromatic Molecules vii. 322 Anthracene derivatives are irradiated with ultraviolet photons.

1971 Nature 2 July 67/2 The dark-adapted human eye is capable of detecting a pulse of less than a hundred photons.

1989 J. Updike Self-consciousness ii. 64 All the family had that curious complexion of tropical whites—a dingy, mat color, the color of sun-avoidance in a climate rife with photons.

2002 M. Crichton Prey 143 We built the units with a small piezo wafer to generate current from photons.

1949 Jrnl. Brit. Interplanetary Soc. 8 242 Two possible schemes for utilizing nuclear energy are then considered, the first using a nuclear ‘boiler’ to heat a working fluid which is then expanded through a nozzle in the normal way and the second using the energy direct in a ‘photon’ rocket.

1958 C. C. Adams et al. Space Flight 347 Others ponder photon rockets driven by parallel beams formed by properly designed reflectors.

1994 New Scientist 17 Sept. 15/3 Einstein's field equations of gravity describe the gravitational field produced by particular distributions of mass, and Bonnor used an exact solution of the equations to describe such a ‘photon rocket’.

1968 S. E. Whitfield in S. E. Whitfield & G. Roddenberry Making of ‘Star Trek’ ii. ii. 194 The Enterprise is equipped with a second type of offensive weapon, called photon torpedos.

1985 M. Larson Pawns & Symbols vi. 82 Wouldn't mind spending some time there collecting specimens—if I had a healthy supply of photon torpedoes and a reliable scanner alarm.

1999 M. J. Friedman My Brother's Keeper ii. v. 101 Hirota was bearing down on him like a photon torpedo.

1953 N.Y. Times 31 Jan. 13/7 The first volume made with the ‘revolutionary’ Higgonet-Moyroud [sic] photographic type-composing machine will be issued by Rinehart on Feb. 26... The machine, commonly called the Photon, a project of the Graphic Arts Research Foundation, Inc., is an electronic device that delivers film negatives instead of type.

1967 N. S. M. Cox & M. W. Grose Organization Bibliogr. Rec. by Computer ii. 45 In the Photon 540 or the Intertype, the characters are held on a disc.

1996 Business Hist. Rev. (Nexis) Spring The whole industry today is based on the concepts that the Photon introduced... The Photon did with mechanical switches what current typesetting machines do with digital electronics.

2002 Forbes (Nexis) 23 Dec. 114 The Photon..could spin out type at least four times faster than the Linotype machine.