Optical Magnification System with CCD

** INTRODUCTION **

(You could skip it and go straight to HIGHLIGHT)

Hello Gentlemen.
My name is Gianpiero Riva and I'm writing from Italy. I am an
electrical engineer and I operate as a freelance in the field of
electronics and software.
Now, with other collaborators, I'm going to develop a system for the
acquisition of macro coloured image of the human skin, hair and scalp
(50x, 200x, 400x magnifying power [*]) in order to digital analyse
them and carry out in this way a report on some of the most common
skin and hair diseases.
The system will be composed from the following elements:
1) A micro-camera (magnifier) for the images acquisition;
2) A personal computer with the micro-camera plugged;
3) A software for the image analyses, for the image watching and for
the patient data storing;
The micro-camera plastic envelop will have an ergonomic shape and to
do so it will be more or less like a computer mouse. Also the optics
will have a plastic envelop (cone-shaped) with an internal lighting
system.
 
Now we are at a very good point with the project: in fact the hardware
(CCD camera board) and the software are now available. So we need to
choose the right optical system and we need to purchase the right
optics and objectives. Then, with the right optics measures and
dimensions we will be able to produce the plastic envelops.


** HIGHLIGHT **

At the URL, 
http://digilander.libero.it/griva
You can find the images referred afterwards.
 
On Fig.1 You can see the "Magnification Chain". We achieve a 37,5x
magnifying power just processing the CCD signal and presenting it in
640x480 resolution image. So to archive a 400x magnifying power [*] we
need more or less 10x magnifying power from the image target to the
CCD. To summarize we have to design 3 optics with the following
magnifying power:
1) 10x
2) 5x
3) 1x

On Fig.2 ("Optics Schema") You can see a transversal section schema of
the optics that we have to design. In the schema, in the plane signed
"A" lies the CCD and in the plane signed "D" lies the target (skin,
hair o scalp): the target positioned in the D-plane must be sharp
focused. The distance between the A-plan and D-plan must be more or
less 7 cm maximum (for morphological reasons: this is our
constraint!).

On the others figures You can see an example of what we are going to
produce watching some photos taken from our competitor's system.

Now:
1) What kind of objective can we use to achieve our purpose?
2) If we could use a microscope objective, what are the specifications
of that objective?
3) What are the distance from A-plan to B-plan and from C-plan and
D-plan? (the last I think is named "Working Distance")
4) Do we have to put a diaphragm between A-plan and B-plan? And if so,
at what distance and with what dimensions?
5) Did our competitor use a diaphragm? (If it's possible to deduce
from the photos)
6) What kind of technology do you think our competitor used? (If it's
possible to deduce from the photos)
7) Where we can purchase the right optics?
 
Thank You very much in advance for all your answers!
Best Wishes,

Gianpiero Riva



** NOTES **

[*] When we say "400x magnifying power" we mean that, for example, a
single hair that has a diameter of 0,1 mm will be presented on the
monitor (specification: LCD, 15'' diagonal, 1024x768 monitor
resolution, 640x480 camera resolution) and will result 400 times
bigger; so we will be able to measure on the monitor surface that
single hair with a diameter of 40 mm.


.....................................
RIVA ing. Gianpiero 
[EMAIL PROTECTED]