Hoffman Modulation

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grgh
Posts: 372
Joined: Sat Mar 09, 2013 4:55 am
Location: Lancashire. UK

Hoffman Modulation

Post by grgh »

Can any one help with instructions for making slit mask for hoff mod.
picked up a couple of objectives, but web instructions seem to be getting very complicated.
Old Age again rearing its head.
used to do astronomy.
and photography.
Zeiss Universal Phase contrast.
Zeiss PMII
B&L stereo zoom.

Pau
Site Admin
Posts: 6053
Joined: Wed Jan 20, 2010 8:57 am
Location: Valencia, Spain

Post by Pau »

I have no experience with Hoffman.
Likely you already know it, but in case of... https://micro.magnet.fsu.edu/primer/tec ... intro.html

https://micro.magnet.fsu.edu/primer/tec ... index.html
Pau

viktor j nilsson
Posts: 423
Joined: Fri Mar 01, 2013 1:43 am
Location: Lund, Sweden

Post by viktor j nilsson »

I've made my own HMC slit mask from an old library card. It was just the right thickness to slide into the rotatable filter slot of my Wild Achr.Apl. condenser.

Image

The righthand image shows the slit and HMC modulator as seen in the back focal plane. I can rotate the filter tray and slide the slit card in and out to align it.

To make it, I printed a grid system (with symbols so I could orient myself) onto an acetate sheet, cut it to the right dimensions to fit in the filter slot, and placed it in the filter slot. I then inspected the modulator and grid as seen at the back focal plane of the objective with a phase telescope. I could then see exactly what grids on the acetate sheet the slit needed to cover to match the medium gray part of the modulator (which I believe is optimal?). I cut out these grids from the acetate sheet, placed it over the library card and traced the outline of the slit. I then cut it with an exacto knife.

Simple as that, works great (but I don't use it often as I find the resolution of the Nikon 40x HMC LWD 0.55 quite disappointing compared to my Fluor 40x 0.85, not to mention my 40x 1.30).

grgh
Posts: 372
Joined: Sat Mar 09, 2013 4:55 am
Location: Lancashire. UK

Post by grgh »

Thank you all for the suggestions, also to the PM's Received.

More to do to finish two mask, but getting there.
used to do astronomy.
and photography.
Zeiss Universal Phase contrast.
Zeiss PMII
B&L stereo zoom.

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