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Aerial scanning
Patent survey British Patent specifications can be obtained f r o m the Sales Branch, National R e f e r e n c e L i b r a r y , Science Division, 25 Southampton Buildings, Holborn, London WC2, quoting patent number and enclosing money o r d e r of 5s. The date given is that on which the complete specification was filed.
METROLOGY AND A L I G H T
Displacement measurement Patent 1 209 342 granted to Olympus Kogaku Kogyo K. K. (Jan. 3, 1966) Displacement amounts a r e m e a s u r e d by s u p e r i m p o s ing the image of one portion of a diffraction grating upon another portion. The strength of the resulting moird fringe pattern v a r i e s sinusoidally in r e s p o n s e to the displacement of the grating. Ranging device Patent 1 212 641 granted to Brown Boveri & Co Ltd. (Jan. 29, 1969) An i n t e r f e r o m e t e r ranging device is capable of m e a suring two path lengths simultaneously.
INSPECTION A N D RECOGNITION Thickness of v a p o u r - d e p o s i t e d f i l m s Patent 1 193 696 granted to L e y b o l d - H e r a e v s V e r waltung GmbH. A light b e a m inside a vacuum c h a m b e r is directed at a stationary or moving object that is being coated with metallic vapour. The intensity of the reflected light is used to determine the thickness of the coated film. Compensation is made f o r s t r a y environmental light.
High-speed photography Patent 1 193 902 granted to US Atomic E n e r g y C o m mission. A method is provided f o r photographing objects that are surrounded by hot luminous gas. A high-density pulsed beam of light is produced by a Q-switched l a s e r and split into three beams. One beam is r e f l e c ted into a delay unit and then through a p o l a r i z e r that rotates it through 90 °. It then p a s s e s to the object. The second beam is reflected into a second delay unit, without passing through a p o l a r i z e r . The third beam p a s s e s straight to the object. The three b e a m s are reflected by the object and then pass through an interference f i l t e r (which p a s s e s only light whose wavelength is close to that of the l a s e r ) before once again being divided into b e a m s that strike three K e r r cell shutters. F i l m behind each K e r r cell is exposed as the individually timed shutters open. Exposure times of 10ns and f r a m e speeds of 5ns a r e reported.
Holographic c h a r a c t e r s e a r c h Patent 1 202 551 granted to British A i r c r a f t Corp Ltd. (Sept. 12, 1968) A method of s e a r c h i n g for one c h a r a c t e r amongst a n u m b e r of them involves f o r m i n g a multiple hologram of all the c h a r a c t e r s , placing the h o l o g r a m in a beam of coherent radiation and rotating it until s u c c e s s i v e holograms a r e bought into the a p e r t u r e position. The t r a n s m i t t e d b e a m is viewed through the F o u r i e r filter of the c h a r a c t e r being searched for. Optical scanning system Patent 1 203 056 granted to Rank X e r o x Ltd. (July 25, 1966) An optical scanning s y s t e m is made up of a number of imaging devices, each consisting of two m i r r o r s arrange[1 between an object and an image plane. The imaging device is moved relative to these planes. The scanning s y s t e m is used to produce a wrongreading copy of a document as in an e l e c t r o s t a t i c copier. I m a g e examination Patent 1 203 260 granted to Soc. Alsacienne de Constructions Atomique de Telecommunications et d'Electronique ' A l c a t e l ' . (Nov. 23, 1967) A number of single or stranded glass f i b r e s t r a n s mit light f r o m a source to a document or image to be studied. A rigid block of such fibres bonded parallel to one another and perpendicular to a polished face is suspended above the document. The upper ends of the f i b r e s are connected to photosensitive cells. P a t t e r n recognition Patent 1 203 466 granted to North A m e r i c a n Rockwell Corp. (Aug. 10, 1967) In o r d e r to determine if two patterns differ, the patt e r n s a r e f i r s t illuminated with coherent light. The diffracted light produces a F r a u n h o f e r pattern in the output focal plane of an optical t r a n s f o r m e r . Surface examination Patent 1 203 640 granted to Rumania, Ministry of Machine Building Industry. (Oct. 17, 1967) The r o u g h n e s s of two s u r f a c e s is determined by s t e r e o s c o p i c c o m p a r i s o n with photographs of standard surfaces.
Character identification Aerial scanning Patent 1 201964 granted to Optische Industrie 'de Oude Delft' N.V. (Dec. 22, 1967) A device f o r use in the periodic scanning of a n a r r o w strip of t e r r a i n extending a c r o s s the path of an a i r craft is made up of a r o t o r having three scanning m i r r o r s and an optical s y s t e m f o r collecting and ~ocussing radiant energy f r o m the m i r r o r s on to a ~iagle detector. A rotating chopper allows b e a m s of energy to be alternately incident on the detector.
Patent 1 204 713 granted to British A i r c r a f t Corp. Ltd. (Aug. 2, 1968) Unknown c h a r a c t e r s or patterns a r e identified using the complex conjugates of the F o u r i e r t r a n s f o r m s of a r e f e r e n c e set of c h a r a c t e r s or patterns. The r e c o r d is illuminated by the F o u r i e r t r a n s f o r m in coherent light of the unknown c h a r a c t e r or pattern. The position of the bright a n t i - c o r r e l a t i o n spot r e l a tive to the c r o s s - c o r r e l a t i o n patterns determines the unknown c h a r a c t e r s o r patterns.
Oplics and Laser Technology
February 1971
47
METROLOGY AND A L I G H T
Displacement measurement Patent 1 209 342 granted to Olympus Kogaku Kogyo K. K. (Jan. 3, 1966) Displacement amounts a r e m e a s u r e d by s u p e r i m p o s ing the image of one portion of a diffraction grating upon another portion. The strength of the resulting moird fringe pattern v a r i e s sinusoidally in r e s p o n s e to the displacement of the grating. Ranging device Patent 1 212 641 granted to Brown Boveri & Co Ltd. (Jan. 29, 1969) An i n t e r f e r o m e t e r ranging device is capable of m e a suring two path lengths simultaneously.
INSPECTION A N D RECOGNITION Thickness of v a p o u r - d e p o s i t e d f i l m s Patent 1 193 696 granted to L e y b o l d - H e r a e v s V e r waltung GmbH. A light b e a m inside a vacuum c h a m b e r is directed at a stationary or moving object that is being coated with metallic vapour. The intensity of the reflected light is used to determine the thickness of the coated film. Compensation is made f o r s t r a y environmental light.
High-speed photography Patent 1 193 902 granted to US Atomic E n e r g y C o m mission. A method is provided f o r photographing objects that are surrounded by hot luminous gas. A high-density pulsed beam of light is produced by a Q-switched l a s e r and split into three beams. One beam is r e f l e c ted into a delay unit and then through a p o l a r i z e r that rotates it through 90 °. It then p a s s e s to the object. The second beam is reflected into a second delay unit, without passing through a p o l a r i z e r . The third beam p a s s e s straight to the object. The three b e a m s are reflected by the object and then pass through an interference f i l t e r (which p a s s e s only light whose wavelength is close to that of the l a s e r ) before once again being divided into b e a m s that strike three K e r r cell shutters. F i l m behind each K e r r cell is exposed as the individually timed shutters open. Exposure times of 10ns and f r a m e speeds of 5ns a r e reported.
Holographic c h a r a c t e r s e a r c h Patent 1 202 551 granted to British A i r c r a f t Corp Ltd. (Sept. 12, 1968) A method of s e a r c h i n g for one c h a r a c t e r amongst a n u m b e r of them involves f o r m i n g a multiple hologram of all the c h a r a c t e r s , placing the h o l o g r a m in a beam of coherent radiation and rotating it until s u c c e s s i v e holograms a r e bought into the a p e r t u r e position. The t r a n s m i t t e d b e a m is viewed through the F o u r i e r filter of the c h a r a c t e r being searched for. Optical scanning system Patent 1 203 056 granted to Rank X e r o x Ltd. (July 25, 1966) An optical scanning s y s t e m is made up of a number of imaging devices, each consisting of two m i r r o r s arrange[1 between an object and an image plane. The imaging device is moved relative to these planes. The scanning s y s t e m is used to produce a wrongreading copy of a document as in an e l e c t r o s t a t i c copier. I m a g e examination Patent 1 203 260 granted to Soc. Alsacienne de Constructions Atomique de Telecommunications et d'Electronique ' A l c a t e l ' . (Nov. 23, 1967) A number of single or stranded glass f i b r e s t r a n s mit light f r o m a source to a document or image to be studied. A rigid block of such fibres bonded parallel to one another and perpendicular to a polished face is suspended above the document. The upper ends of the f i b r e s are connected to photosensitive cells. P a t t e r n recognition Patent 1 203 466 granted to North A m e r i c a n Rockwell Corp. (Aug. 10, 1967) In o r d e r to determine if two patterns differ, the patt e r n s a r e f i r s t illuminated with coherent light. The diffracted light produces a F r a u n h o f e r pattern in the output focal plane of an optical t r a n s f o r m e r . Surface examination Patent 1 203 640 granted to Rumania, Ministry of Machine Building Industry. (Oct. 17, 1967) The r o u g h n e s s of two s u r f a c e s is determined by s t e r e o s c o p i c c o m p a r i s o n with photographs of standard surfaces.
Character identification Aerial scanning Patent 1 201964 granted to Optische Industrie 'de Oude Delft' N.V. (Dec. 22, 1967) A device f o r use in the periodic scanning of a n a r r o w strip of t e r r a i n extending a c r o s s the path of an a i r craft is made up of a r o t o r having three scanning m i r r o r s and an optical s y s t e m f o r collecting and ~ocussing radiant energy f r o m the m i r r o r s on to a ~iagle detector. A rotating chopper allows b e a m s of energy to be alternately incident on the detector.
Patent 1 204 713 granted to British A i r c r a f t Corp. Ltd. (Aug. 2, 1968) Unknown c h a r a c t e r s or patterns a r e identified using the complex conjugates of the F o u r i e r t r a n s f o r m s of a r e f e r e n c e set of c h a r a c t e r s or patterns. The r e c o r d is illuminated by the F o u r i e r t r a n s f o r m in coherent light of the unknown c h a r a c t e r or pattern. The position of the bright a n t i - c o r r e l a t i o n spot r e l a tive to the c r o s s - c o r r e l a t i o n patterns determines the unknown c h a r a c t e r s o r patterns.
Oplics and Laser Technology
February 1971
47