- Email: [email protected]
Prof Hopkins ICO President
RECENT DEVELOPMENTS
Photo-matrix for moire fringe work WORK on photovoltalc cells for space use has led to development of a photocell m a t r i x for m o i r e fringe machine control. Thin film cadmium sulphide/copper sulphide heterojunction cells, investigated at IRD as an alternative to silicon ' s o l a r ' cells, a r e fabricated in m a t r i c e s of 100 and 1000 photovoltaic lines per inch. The a r r a y s are used in a displacement m e a s u r i n g grating s y s t e m designed to operate on a reflection basis. In Fig. la a simple m o i r e fringe s y s t e m is shown with a fixed scale grating and a movable index grating. The separate detector can be eliminated and the s y s t e m simplified by making each line on the index grating into a photodetector (Fig. lb). If the second grating is made reflective the d e t e c t o r s can form the f i r s t grating, Fig. lc. The fixed elements in the s y s t e m are now on one side of the broken line and the moving p a r t s on the other, simplifying machine mounting. The d e t e c t o r s a r e made by vacuum deposition of ptype CdS to 5-10~m thick on a glass substrate with c h r o m e / g o l d deposited to f o r m one set of contacts (Fig. ld). Effects of ambient light on the s y s t e m can be eliminated by connecting cells in quadrature, using four times the number of cells. This also r e s u l t s in availability of sine and cosine outputs and i n c r e a s e s sensitivity. The devices were d e s c r i b e d by R. S. Pinder, L. Clark, K. Moore & R. S. Mytton at the Solid-State Devices Conference, Exeter, 8-12 September.
PROF H O P K I N S ICO P R E S I D E N T PROFESSOR H. H. Hopkins of the University of Reading has been elected P r e s i d e n t of the I n t e r national C o m m i s s i o n for Optics, in s u c c e s s i o n to P r o f e s s o r G. Toraldo di F r a n c i a . P r o f e s s o r Hopkins is well-known for his contributions to optics including the invention (independently with Van Heel) of fibre optics, the design of zoom lenses and m o r e recently novel types of medical endoscope. F o r his work on diffraction and coherence theory and optical t r a n s f e r functions, he was elected the 21st Thomas Young O r a t o r in 1961 by the P h y s i c a l Society and received an h o n o r a r y doctorate of the University of Besan~on in the same y e a r . P r o f e s s o r Hopkins moved to Reading f r o m I m p e r i a l College in 1967. He was appointed to a new Chair in Applied Optics established at Reading by a generous grant f r o m Rank P r e c i s i o n Industries (then Taylor Hobson Division of Rank). The new department already
284
optics Technology
November 1969
a
~coa~eng
Indexgrating intoindexgroting
.~deff
~ C
use region
iI~speculor reflector potymerised orthoresist.. Cu2S _
_
_
_
p-t pe
~ ~ . - - - - - C d s 5-10llm g loss ~"'-opoque ~'g light chrome/gold
Fig. la-c. Evolution of reflection grating system for machine displacement measurement using heterojunction photomatrix. (d) Construction of graling.
has a successful o n e - y e a r M. Sc. c o u r s e in Applied and Modern Optics, and this may be followed p a r t time over a period of two y e a r s . R e s e a r c h in the new group includes advanced computer techniques for optical design, theoretical studies in diffraction and coherence, p r e c i s i o n i n t e r f e r o m e t r y , t h i n - f i l m s and coherent optical techniques for optical data processing.
AIR POLLUTION MONITOR ATMOSPHERIC POLLUTION is being monitored using a pulsed ruby l a s e r s y s t e m to locate the source of pollution. The r e c e i v e r s y s t e m consists of 3Ocm receiving m i r r o r and photomultiplier tube with provisions for monitoring input and output powers and including water cooling for the l a s e r . An adjustable r a n g e - g a t e can be set to the d e s i r e d a c c u r a c y up to
Photo-matrix for moire fringe work WORK on photovoltalc cells for space use has led to development of a photocell m a t r i x for m o i r e fringe machine control. Thin film cadmium sulphide/copper sulphide heterojunction cells, investigated at IRD as an alternative to silicon ' s o l a r ' cells, a r e fabricated in m a t r i c e s of 100 and 1000 photovoltaic lines per inch. The a r r a y s are used in a displacement m e a s u r i n g grating s y s t e m designed to operate on a reflection basis. In Fig. la a simple m o i r e fringe s y s t e m is shown with a fixed scale grating and a movable index grating. The separate detector can be eliminated and the s y s t e m simplified by making each line on the index grating into a photodetector (Fig. lb). If the second grating is made reflective the d e t e c t o r s can form the f i r s t grating, Fig. lc. The fixed elements in the s y s t e m are now on one side of the broken line and the moving p a r t s on the other, simplifying machine mounting. The d e t e c t o r s a r e made by vacuum deposition of ptype CdS to 5-10~m thick on a glass substrate with c h r o m e / g o l d deposited to f o r m one set of contacts (Fig. ld). Effects of ambient light on the s y s t e m can be eliminated by connecting cells in quadrature, using four times the number of cells. This also r e s u l t s in availability of sine and cosine outputs and i n c r e a s e s sensitivity. The devices were d e s c r i b e d by R. S. Pinder, L. Clark, K. Moore & R. S. Mytton at the Solid-State Devices Conference, Exeter, 8-12 September.
PROF H O P K I N S ICO P R E S I D E N T PROFESSOR H. H. Hopkins of the University of Reading has been elected P r e s i d e n t of the I n t e r national C o m m i s s i o n for Optics, in s u c c e s s i o n to P r o f e s s o r G. Toraldo di F r a n c i a . P r o f e s s o r Hopkins is well-known for his contributions to optics including the invention (independently with Van Heel) of fibre optics, the design of zoom lenses and m o r e recently novel types of medical endoscope. F o r his work on diffraction and coherence theory and optical t r a n s f e r functions, he was elected the 21st Thomas Young O r a t o r in 1961 by the P h y s i c a l Society and received an h o n o r a r y doctorate of the University of Besan~on in the same y e a r . P r o f e s s o r Hopkins moved to Reading f r o m I m p e r i a l College in 1967. He was appointed to a new Chair in Applied Optics established at Reading by a generous grant f r o m Rank P r e c i s i o n Industries (then Taylor Hobson Division of Rank). The new department already
284
optics Technology
November 1969
a
~coa~eng
Indexgrating intoindexgroting
.~deff
~ C
use region
iI~speculor reflector potymerised orthoresist.. Cu2S _
_
_
_
p-t pe
~ ~ . - - - - - C d s 5-10llm g loss ~"'-opoque ~'g light chrome/gold
Fig. la-c. Evolution of reflection grating system for machine displacement measurement using heterojunction photomatrix. (d) Construction of graling.
has a successful o n e - y e a r M. Sc. c o u r s e in Applied and Modern Optics, and this may be followed p a r t time over a period of two y e a r s . R e s e a r c h in the new group includes advanced computer techniques for optical design, theoretical studies in diffraction and coherence, p r e c i s i o n i n t e r f e r o m e t r y , t h i n - f i l m s and coherent optical techniques for optical data processing.
AIR POLLUTION MONITOR ATMOSPHERIC POLLUTION is being monitored using a pulsed ruby l a s e r s y s t e m to locate the source of pollution. The r e c e i v e r s y s t e m consists of 3Ocm receiving m i r r o r and photomultiplier tube with provisions for monitoring input and output powers and including water cooling for the l a s e r . An adjustable r a n g e - g a t e can be set to the d e s i r e d a c c u r a c y up to