Back Focal Plan of Olympus BX Objectives

[microb]

Does anyone have a table of the back focal plane positions of the following objectives?

Also does anyone have pointers to the best procedure to measure the back focal plane position?

Thanks.

Olympus Objectives:
37543 UPLFL 20x 0,5
37553 UPLFL 20x PH 0,5
37557 UPLFL 20x PH/NH 0,5
UPLFLN20x 0,5
LUCPLFLN20x 0,45
UPLFLN20x PH 0,5
LUCPLFLN20X PH 0,45

[viktor j nilsson]

https://www.researchgate.net/post/Is_th ... ctive_lens

I've used the method described by Paolo Pizza with good results. It's much harder at 40x and above.

[MichaelG.]

Forgive me if I am missing the point, but; surely [when in use as intended] the back focal plane of an infinity-corrected objective is at infinity.

It is only when either used incorrectly, or used in combination with the tube lens, that there is an identifiable plane.

MichaelG.
.
.

https://www.microscopyu.com/tutorials/i ... microscope
https://www.quekett.org/resources/under ... ectives-ii

[microb]

Forgive me if I am missing the point, but; surely [when in use as intended] the back focal plane of an infinity-corrected objective is at infinity.

It is only when either used incorrectly, or used in combination with the tube lens, that there is an identifiable plane.

MichaelG.
.
.

https://www.microscopyu.com/tutorials/i ... microscope
https://www.quekett.org/resources/under ... ectives-ii

The BFP is where the epi focuses the light and where the DIC prism is aimed at as well.

(https://www.thorlabs.com/newgrouppage9. ... up_id=8565)

[MichaelG.]

.

O.K. ... it seems I must be missing the point

I will watch and learn.

MichaelG.
.

Edit: [self-help]

Collimated space starts at the back focal plane which falls inside the objectives, generally deeper inside for higher magnification. Olympus now specifies the location of the back focal plane and other manufacturers may provide the location if asked nicely, or you can measure it. 2)
.

2) To measure the position of the back focal plane of an objective: place an ideal lens outside the objective and adjust its position along the optical axis until collimated light into the pair of lenses in either direction results in collimated light coming out. The external lens is now focused at the back focal plane, so remove the objective lens and see where the external lens is focused.

Ref. http://asiimaging.com/docs/infinity_microscope_basics

[microb]

I'm still trying to figure out a bunch of this as well.

[microb]

https://www.researchgate.net/post/Is_th ... ctive_lens

I've used the method described by Paolo Pizza with good results. It's much harder at 40x and above.

Thanks. I'll take a look. I hadn't thought about get a linear set of position points. I thought I'd have to use a ultra long working distance Mitutoyo objective to aim inside the back of the test objective to find a focal point if collimated light came in from the sample side. The linear sampling approach looks like a more reliable data set.

[hans]

Looks like at least some of the ones you are interested in are given on Olympus's web site, UPLFLN20X for example specifies BFP position -19.1 mm:
https://www.olympus-lifescience.com/en/ ... 06530.html