In a message dated 31/05/01, jmhannon@........ writes:

> Having looked into building a spectrophotometer using a linerar CCD array, I 
> know a bit about how they work. This web site 
> 
> 
> 
> 
> 
> http://www.kodak.com/cgi-bin/webCatalog.pl?product=KODAK+KLI+Series+Image+Sensors
> &cc=US&lc=en 
> shows Kodak offerings. 

Dear Jim Hannon,

       Thank you for the reference. I note that the KLI-8811 has 8,800 pixels 
7 x 7 microns and is a single row of cells. This might give ~ +/-12 bit 
accuracy (4096) about the centre zero. The problem that is still puzzling me 
is how to use this clever device to measure small enough angles and how to 
keep it stable? The movement due to the six second seismic background is of 
the order of 1 to 5 microns and you would normally set your A/D to give >128 
counts for this.

       Assuming that you had a small Lehman with a 1 ft beam, you need an 
angular gain of x560 to get one pixel to represent 1 count. A 260 ft optical 
lever which focussed to a spot of 7 microns might be a bit impractical. I 
suppose that you could use two surface silvered optically flat mirror bars 
and reflect the light 9 times, but I suspect that you would need a very 
expensive laser. The small solid state lasers  don't seem to give well enough 
defined or focussed beams. Getting such a device designed, set up, aligned 
and stable sounds like the sort of task that I would prefer to leave to 
others. How do you plan to do it Dave?

       Regards,

       Chris Chapman

In a message dated 31/05/01, jmhannon@........ writes:



Having
 looked into building a spectrophotometer using a linerar CCD array, I 

know a bit about how they work. This web site 











http://www.kodak.com/cgi-bin/webCatalog.pl?product=KODAK+KLI+Series+Image+Sensors

&cc=US&lc=en 

shows Kodak offerings. 




Dear Jim Hannon,



       Thank you for the reference. I note that the KLI-8811 has 8,800 pixels 

7 x 7 microns and is a single row of cells. This might give ~ +/-12 bit 

accuracy (4096) about the centre zero. The problem that is still puzzling me 

is how to use this clever device to measure small enough angles and how to 

keep it stable? The movement due to the six second seismic background is of 

the order of 1 to 5 microns and you would normally set your A/D to give >128 

counts for this.



       Assuming that you had a small Lehman with a 1 ft beam, you need an 

angular gain of x560 to get one pixel to represent 1 count. A 260 ft optical 

lever which focussed to a spot of 7 microns might be a bit impractical. I 

suppose that you could use two surface silvered optically flat mirror bars 

and reflect the light 9 times, but I suspect that you would need a very 

expensive laser. The small solid state lasers  don't seem to give well enough 

defined or focussed beams. Getting such a device designed, set up, aligned 

and stable sounds like the sort of task that I would prefer to leave to 

others. How do you plan to do it Dave?



       Regards,



       Chris Chapman