Megadiascope. 



1215 



Ives Trichrome Apparatus. Fig. 23. 



II. Projection in Natural Colours with the Ives 

 Trichrome Apparatus (Fig. 23). 



The Ives trichrome apparatus (F i g. 23), 

 which is specially arranged for the megadiascope, 

 is placed on the optical bench. By combining 

 the three plain images a beautifully coloured 

 image is obtained on the screen. 



as 



a 



~* 



o> 



8 



12. Projection in natural colours by means of the Diffraction Chromoscope (German Design) 



(Fig. 24). 



In this method of producing coloured images, the images are obtained by the aid of diffraction 

 gratings. Small surfaces with gratings of various shape and width of line are arranged alongside each 

 other in such manner that when illuminated the images (e. g., of baskets of fruit, butterflies, etc.) are 

 reproduced in their true natural tints. The colour reproduction is additive; no light filter is employed, 

 and all mixed colours are arrived at by the superposition of spectral tints. The plates containing the 

 image are obtained photographically and are therefore correct. 



Diffraction Chromoscope 

 Fig. 24. 1 : 12. 



Cinematograph. 

 Fig. 25. 1 : 4. 



In reproducing the images the light shading box (F i g. 24) is placed on the optical bench in 

 front of the projection lens, the horizontal slit of the box being turned towards the projector. The 

 following are also erected on the bench: a bi-concave lens with diaphragm, a slit adjustable as regards 

 height by rack and pinion, and having a diaphragm; and an achromatic objective also adjustable for 

 height (see the illustration, F i g. 24). By means of the bi-concave lens a sharp image is obtained, 

 on the diaphragm of the slit, of the slit arranged on the shading box. If now a "grating" image pro- 

 duced by Wood's process is placed in the change frame at the front end of the box, a number of dif- 

 fraction spectra appear on the diaphragm of the slit in addition to the brilliant image of the slit. The 

 slit (adjustable as regards height) is now placed at the position of the diffraction spectrum immediately 

 adjacent to the slit-image, and a sharp image is cast on the projection screen by means of the achromatic 

 objective; this is the coloured image. By raising and lowering the diaphragm of the slit and altering 

 the width of the slit itself the tinting of the image is varied until the correct, tones are arrived at. 

 For showing the course of the rays in the light-shielding box and proving that box contains no other 

 auxiliary apparatus, it is provided with Flap doors on the two longitudinal sides, and these can 

 be easily opened; an iinimpeded view is then possible. 



A complete descriptive catalogue of the Diffraction Chromoscope will be forwarded if desired. 



Cl. 278. 3824. 280. 



