Re: Optical Magnification System with CCD

"Gianpiero Riva" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> ** 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]

The point you missed here is that magnification is utterly meaningless.  You
need to know Numerical Aperature and working distance first, then there are
about 14 other items you need to know like what type of correction you are
going to use.  You might want to consider an OEM optical system from
Olympus, Nikon, Leica or Zeiss.

Kevin Cunningham