- Email: [email protected]
Holographic plate material
m e a s u r e d directly while the c i r c u i t is being adjusted for gain p r e c i s i o n . Cost is about $13 000. TRW I n s t r u m e n t s , 139 Illinois Street, E1 Segundo, California 90245.
LENSLESS BENCH MAGNIFIER
A production bench magnifier c l a i m s to minimise spherical and chromatic a b e r r a t i o n by using a f r o n t s i l v e r e d m i r r o r . The 5 x 10cm m i r r o r gives a m a g nification of six. Illumination is provided by two 8W miniature f l o u r e s c e n t tubes. The i n s t r u m e n t (model AL. 6) is intended f o r inspection of components up to 2 . 5 c m diameter. (Price: £27).
p l a n e - m i r r o r and the light t r a v e l s a total r e t u r n path length of only 6m. Over such a short distance the apparatus can be easily aligned by the average s i x t h - f o r m student. A 3cm high 12V motor turns a tiny aluminized opticfiat at n e a r l y 40 0 0 0 r e v / m i n . Light t r a v e l s the 6m in 2 x 10-8s and so the m i r r o r r o t a t e s only 0.004 ° in this time; the r e t u r n beam of light, seen in an eyepiece l m f r o m the m i r r o r , is displaced by 0 . 1 5 m m and this can be easily m e a s u r e d by a m i c r o m e t e r adjustment of the c r o s s - w i r e s of the eyepiece. The motor will spin in either direction; so the total displacement of the beam is 0 . 3 0 m m and with no z e r o error. >
The s h o r t path length enables a relatively short trough of water to be introduced to d e m o n s t r a t e effectively
P. W. Allen and Co, 253 Liverpool Road, London N1. -~
1.5m
Plane ~. Ptane mirror ~ O C C~o ndenser lens
/ Q
t lefgth tens =~(uncorrected) ~ * " ~ a t i n g Stit \ uZ__.~_.==..=---"'G'~ss Za pt at e Pmiane r
~!~.,.~z~.
Quartz-iodine tamp
"
_.
.
r
V . ,Mi omet cross-wi s
.
Eyepiece
Method of determining velocity of light by rotating m i r r o r method.
that light t r a v e l s m o r e slowly Ln a medium than in air. A c c u r a c y is s u r p r i s i n g l y good for so simple an a r r a n g e m e n t ; typical r e s u l t s f r o m a c l a s s of sixthf o r m e r s range f r o m 2.8 to 3.2 x 10am s - l , but probably m o r e important than this is that it d e m o n s t r a t e s unequivocally that light does take a finite time to travel f r o m one point to another. I. D. T a y l o r
Inspection magnifier with 5 × ]Ocm mirror.
HOLO(Ht,kPHIC P L A T E M A T E R I A L
VELOCITY OF LIGHT DETERMINATION BY SCHOOLS
Plate m a t e r i a l which allows r e t r i e v a l of information f r o m high density optical m e m o r y s y s t e m s with as little as one-twentieth of the l a s e r beam power r e quired by conventional holographic plates has been developed.
It is becoming common p r a c t i c e in m o d e r n physics teaching to involve the pupils in their own d i s c o v e r y of the laws of physics and experimental m e a s u r e ments of fundamental constants. To d e t e r m i n e the speed of light normally involves long path lengths and expensive apparatus. One r e cently developed inexpensive piece of equipment is in use at B i s h o p ' s Stortford College, Herts. The method r e v i v e s F o u c a u l t ' s idea of a rotating
56
Optics Technology
N o v e m b e r 1968
The new material, dichromated gelatin, has been used at Bell Telephone Labs for r e c o r d i n g high density information and f o r producing s p e c t r o s c o p i c diffraction gratings--used f o r breaking white light into its component wavelengths. Efficiencies as high as 96% have been obtained with plates using the new holographic material, compared with efficiencies of l e s s than 6% f o r conventional holographic plates. This m e a n s that f o r the simplest type of hologram as much as 96% of the r e c o n s t r u c t -
ing b e a m p a s s e s through the h o l o g r a m to i l l u m i n a t e the g r a t i n g p a t t e r n p r o d u c e d by the i n t e r f e r i n g b e a m s . Such an i m a g e i s much b r i g h t e r than that r e c o n s t r u c ted f r o m conventional h o l o g r a p h i c p l a t e s , which can e f f e c t i v e l y u s e l e s s than 6% of a r e c o n s t r u c t i n g b e a m for illumination. The new m a t e r i a l can be u s e d f o r r a p i d l y and e c o n o m i c a l l y p r o d u c i n g quality s p e c t r o s c o p i c d i f f r a c t i o n g r a t i n g s . T h e s e g r a t i n g s a r e n o r m a l l y made m e c h a n ically. Although d i c h r o m a t e compounds have long been u s e d in photography t h e r e has been no p r o c e s s i n g t e c h n i que that would allow t h e i r u s e in holography. In the technique d e v i s e d a d i c h r o m a t e d gelatin f i l m , e x p o s e d to an a r g o n l a s e r beam, i s d e v e l o p e d by m i l d l y a g i t a t ing it in w a t e r . Then the f i l m i s r i n s e d in i s o p r o p a n o l and a i r d r i e d . The r e s u l t i n g g r a t i n g can be p r o t e c t e d a g a i n s t the e f f e c t s of humidity v a r i a t i o n s by coating it with a l a c q u e r that does not cause a s i g n i f i c a n t l o s s of d i f f r a c t i n g power.
Reconstruction of scene recorded holography at 13km distance. Image is reinforced to show location.
scope. The h o l o g r a m was m a d e at night u n d e r c o n d i tions of p o o r v i s i b i l i t y . A s u g g e s t e d i m p r o v e m e n t in the technique i s the u s e of a f o i l - l i n e d p a r a b o l o i d r e f l e c t o r and t e l e v i s i o n c a m e r a in p l a c e of the t e l e scope and f i l m . The c a m e r a output could be fed into a computer for image processing. The e x p e r i m e n t , s p o n s o r e d by the US A i r Force, was c a r r i e d out by David J a c k s o n & Matt L e h m a n n of Stanford U n i v e r s i t y .
LENSES ARE OUR BUSINESS Your enquiries solicited for all High Grade Lenses used for Industrial Photography, Oscillograph Recording, Television, etc. Also CONDENSERS, ACHROMATIC DOUBLETS, IRIS DIAPHRAGMS.
Bright areas on card illustrate high efficiency of spectroscopic diffraction grating etched in dichrom a t e d gelatin.
S A T E L L I T E HOLOGRAMS ? L o n g - d i s t a n c e h o l o g r a m s c l a i m the advantage that effects due to a t m o s p h e r i c d i s t o r t i o n a r e r e d u c e d . The p o s s i b i l i t y of making h o l o g r a m s of s a t e l l i t e s in e a r t h o r b i t c a m e a l i t t l e n e a r e r r e a l i t y when an holog r a m r e c o r e d at 13km was r e c o n s t r u c t e d (see i l l u s t r a t i o n ) . The technique was f i r s t d e m o n s t r a t e d 2 y e a r s ago by P r o f . J. Goodman (Standford U n i v e r s i t y ) under l a b o r a t o r y conditions with g l a s s as the d i s t o r t i n g medium. A o n e - j o u l e ruby l a s e r p r o v i d e d 50mW or power i l l u minating the s c e n e - - a man with pipe standing in f r o n t of a r e f l e c t i n g s u r f a c e . R e c e i v e r was a 1 . 2 m t e l e -
2 in. (51 mm,)f]l Oscilac Anastigmat Lens in Rigid Iris Mount
The call for optics in industry covers a very wide field and at The House of Dallmeyer you will find a ready welcome to discuss and satisfy your requirements. Literature available.
J. H. DALLMEYER LTD., The Lens Specialists for over 100 years CHURCH END WORKS, HIGH ROAD, WlLLESDEN Telephone 01-459 6521-3
Optics Technology
N o v e m b e r 1968
57
LENSLESS BENCH MAGNIFIER
A production bench magnifier c l a i m s to minimise spherical and chromatic a b e r r a t i o n by using a f r o n t s i l v e r e d m i r r o r . The 5 x 10cm m i r r o r gives a m a g nification of six. Illumination is provided by two 8W miniature f l o u r e s c e n t tubes. The i n s t r u m e n t (model AL. 6) is intended f o r inspection of components up to 2 . 5 c m diameter. (Price: £27).
p l a n e - m i r r o r and the light t r a v e l s a total r e t u r n path length of only 6m. Over such a short distance the apparatus can be easily aligned by the average s i x t h - f o r m student. A 3cm high 12V motor turns a tiny aluminized opticfiat at n e a r l y 40 0 0 0 r e v / m i n . Light t r a v e l s the 6m in 2 x 10-8s and so the m i r r o r r o t a t e s only 0.004 ° in this time; the r e t u r n beam of light, seen in an eyepiece l m f r o m the m i r r o r , is displaced by 0 . 1 5 m m and this can be easily m e a s u r e d by a m i c r o m e t e r adjustment of the c r o s s - w i r e s of the eyepiece. The motor will spin in either direction; so the total displacement of the beam is 0 . 3 0 m m and with no z e r o error. >
The s h o r t path length enables a relatively short trough of water to be introduced to d e m o n s t r a t e effectively
P. W. Allen and Co, 253 Liverpool Road, London N1. -~
1.5m
Plane ~. Ptane mirror ~ O C C~o ndenser lens
/ Q
t lefgth tens =~(uncorrected) ~ * " ~ a t i n g Stit \ uZ__.~_.==..=---"'G'~ss Za pt at e Pmiane r
~!~.,.~z~.
Quartz-iodine tamp
"
_.
.
r
V . ,Mi omet cross-wi s
.
Eyepiece
Method of determining velocity of light by rotating m i r r o r method.
that light t r a v e l s m o r e slowly Ln a medium than in air. A c c u r a c y is s u r p r i s i n g l y good for so simple an a r r a n g e m e n t ; typical r e s u l t s f r o m a c l a s s of sixthf o r m e r s range f r o m 2.8 to 3.2 x 10am s - l , but probably m o r e important than this is that it d e m o n s t r a t e s unequivocally that light does take a finite time to travel f r o m one point to another. I. D. T a y l o r
Inspection magnifier with 5 × ]Ocm mirror.
HOLO(Ht,kPHIC P L A T E M A T E R I A L
VELOCITY OF LIGHT DETERMINATION BY SCHOOLS
Plate m a t e r i a l which allows r e t r i e v a l of information f r o m high density optical m e m o r y s y s t e m s with as little as one-twentieth of the l a s e r beam power r e quired by conventional holographic plates has been developed.
It is becoming common p r a c t i c e in m o d e r n physics teaching to involve the pupils in their own d i s c o v e r y of the laws of physics and experimental m e a s u r e ments of fundamental constants. To d e t e r m i n e the speed of light normally involves long path lengths and expensive apparatus. One r e cently developed inexpensive piece of equipment is in use at B i s h o p ' s Stortford College, Herts. The method r e v i v e s F o u c a u l t ' s idea of a rotating
56
Optics Technology
N o v e m b e r 1968
The new material, dichromated gelatin, has been used at Bell Telephone Labs for r e c o r d i n g high density information and f o r producing s p e c t r o s c o p i c diffraction gratings--used f o r breaking white light into its component wavelengths. Efficiencies as high as 96% have been obtained with plates using the new holographic material, compared with efficiencies of l e s s than 6% f o r conventional holographic plates. This m e a n s that f o r the simplest type of hologram as much as 96% of the r e c o n s t r u c t -
ing b e a m p a s s e s through the h o l o g r a m to i l l u m i n a t e the g r a t i n g p a t t e r n p r o d u c e d by the i n t e r f e r i n g b e a m s . Such an i m a g e i s much b r i g h t e r than that r e c o n s t r u c ted f r o m conventional h o l o g r a p h i c p l a t e s , which can e f f e c t i v e l y u s e l e s s than 6% of a r e c o n s t r u c t i n g b e a m for illumination. The new m a t e r i a l can be u s e d f o r r a p i d l y and e c o n o m i c a l l y p r o d u c i n g quality s p e c t r o s c o p i c d i f f r a c t i o n g r a t i n g s . T h e s e g r a t i n g s a r e n o r m a l l y made m e c h a n ically. Although d i c h r o m a t e compounds have long been u s e d in photography t h e r e has been no p r o c e s s i n g t e c h n i que that would allow t h e i r u s e in holography. In the technique d e v i s e d a d i c h r o m a t e d gelatin f i l m , e x p o s e d to an a r g o n l a s e r beam, i s d e v e l o p e d by m i l d l y a g i t a t ing it in w a t e r . Then the f i l m i s r i n s e d in i s o p r o p a n o l and a i r d r i e d . The r e s u l t i n g g r a t i n g can be p r o t e c t e d a g a i n s t the e f f e c t s of humidity v a r i a t i o n s by coating it with a l a c q u e r that does not cause a s i g n i f i c a n t l o s s of d i f f r a c t i n g power.
Reconstruction of scene recorded holography at 13km distance. Image is reinforced to show location.
scope. The h o l o g r a m was m a d e at night u n d e r c o n d i tions of p o o r v i s i b i l i t y . A s u g g e s t e d i m p r o v e m e n t in the technique i s the u s e of a f o i l - l i n e d p a r a b o l o i d r e f l e c t o r and t e l e v i s i o n c a m e r a in p l a c e of the t e l e scope and f i l m . The c a m e r a output could be fed into a computer for image processing. The e x p e r i m e n t , s p o n s o r e d by the US A i r Force, was c a r r i e d out by David J a c k s o n & Matt L e h m a n n of Stanford U n i v e r s i t y .
LENSES ARE OUR BUSINESS Your enquiries solicited for all High Grade Lenses used for Industrial Photography, Oscillograph Recording, Television, etc. Also CONDENSERS, ACHROMATIC DOUBLETS, IRIS DIAPHRAGMS.
Bright areas on card illustrate high efficiency of spectroscopic diffraction grating etched in dichrom a t e d gelatin.
S A T E L L I T E HOLOGRAMS ? L o n g - d i s t a n c e h o l o g r a m s c l a i m the advantage that effects due to a t m o s p h e r i c d i s t o r t i o n a r e r e d u c e d . The p o s s i b i l i t y of making h o l o g r a m s of s a t e l l i t e s in e a r t h o r b i t c a m e a l i t t l e n e a r e r r e a l i t y when an holog r a m r e c o r e d at 13km was r e c o n s t r u c t e d (see i l l u s t r a t i o n ) . The technique was f i r s t d e m o n s t r a t e d 2 y e a r s ago by P r o f . J. Goodman (Standford U n i v e r s i t y ) under l a b o r a t o r y conditions with g l a s s as the d i s t o r t i n g medium. A o n e - j o u l e ruby l a s e r p r o v i d e d 50mW or power i l l u minating the s c e n e - - a man with pipe standing in f r o n t of a r e f l e c t i n g s u r f a c e . R e c e i v e r was a 1 . 2 m t e l e -
2 in. (51 mm,)f]l Oscilac Anastigmat Lens in Rigid Iris Mount
The call for optics in industry covers a very wide field and at The House of Dallmeyer you will find a ready welcome to discuss and satisfy your requirements. Literature available.
J. H. DALLMEYER LTD., The Lens Specialists for over 100 years CHURCH END WORKS, HIGH ROAD, WlLLESDEN Telephone 01-459 6521-3
Optics Technology
N o v e m b e r 1968
57