How to Measure Magnification of a Lens System with Liquid Surface

[berkeman]

Surely if I did that the image of the elements on the bottom of the container that I am trying to take will be distorted, right?

Which comment are you replying to? And I'm pretty sure that neither of them like to be called Shirley.

 

[Drakkith]

What if you place a plano-covex lens at the bottom of container, flat side towards bottom and observe the cuvette through the convex side of the lens? The aim of such lens is to form sort of Galilean telescopic system in combination with the negative water meniscus. In that case the illumination system woud function as it should.

The problem is that by the time the light passes through the bottom of the sample much of it has already been lost. Plus that will require modification of the camera end of the system since you have introduced a positive lens into it.

 

[HomeTinker]

Which comment are you replying to? And I'm pretty sure that neither of them like to be called Shirley.

Apologies, that was a reply to the idea of adding plano-convex lens on the bottom of the container.

 

[HomeTinker]

The problem is that by the time the light passes through the bottom of the sample much of it has already been lost. Plus that will require modification of the camera end of the system since you have introduced a positive lens into it.

Modification of the camera lens is possible, there is a complete freedom on that side. What I cannot do is to interfere with the container itself or it's content.

 

[Drakkith]

Modification of the camera lens is possible, there is a complete freedom on that side. What I cannot do is to interfere with the container itself or it's content.

Like I said, I think you will have already lost too much light by the time it reaches the new lens, but you could always try it. I'd recommend reaching out to an optical engineer and getting their professional opinion on the matter.

 

[Gleb1964]

The problem is that by the time the light passes through the bottom of the sample much of it has already been lost. Plus that will require modification of the camera end of the system since you have introduced a positive lens into it.

I haven't seen specification for the system, but I guess it not on a limit of signal/noise. The aim is to get evenly illuminated background field, not the best efficiency of using every photon. You may mention, there is a caple of apertures truncating a lot of light.

 

[Drakkith]

I haven't seen specification for the system, but I guess it not on a limit of signal/noise.

Indeed. That wasn't what I was trying to get at. My apologies for the confusion.

 

[HomeTinker]

I haven't seen specification for the system, but I guess it not on a limit of signal/noise. The aim is to get evenly illuminated background field, not the best efficiency of using every photon. You may mention, there is a caple of apertures truncating a lot of light.

There are two diaphragms in the system as per koehler design (field and aperture diaphragms) however to be honest they may very little difference here. Having them completely opened or closed do not improve on this situation.

 

[Gleb1964]

I have raytraced two options, with plano-convex lens above cuvette and below. Both options are working somehow, but not the same.
Variant with lens above cuvette does not give even illumination over entire field. Illumination is even at the central field but does not goes to the edge. Vignetting is increasing close to edge and at the very edge there is a dark rim because light undergo a total internal reflection and does not pass through.
Another option with the same lens under cuvette so the imaging optics is looking at cuvette bottom through the planoconvex lens. That does destroy telecentricity condition of imaging optics but makes possible to achive even illumination over entire cuvette bottom.
What trade of is preferable is at the topic starter choice.

 

[sophiecentaur]

Both options are working somehow, but not the same.

That doesn't surprise me too much. There is a right end and a wrong end for binoculars too.

 

[HomeTinker]

Many thanks for that, I will try to get hold of LA1859 and see what results that makes for both designs.