Olympus AX/BX/IX DIC

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microb
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Olympus AX/BX/IX DIC

#1 Post by microb » Wed Jan 22, 2020 11:23 pm

Hi,

Regarding transmission DIC, why/how does the Olympus BX level of microscopes have different magnification DIC prisms for the condenser (U-UCDB-2), but one DIC prism to that goes into the objective turret (U-DICT) used for any objective. Does the U-DICT slide allow it to move the interference plane up and down? And does it need to be adjusted each time the turret is changed? If so then it seems that a motored option would be available for the motored turret to be a valid set up.

Any links to on describing the light path would be appreciated.

https://www.ebay.com/itm/Olympus-U-DICT ... Sw-jBdfIsd
https://www.ebay.com/itm/Olympus-U-UCDB ... SwoI5dFY20

einman
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Re: Olympus AX/BX/IX DIC

#2 Post by einman » Thu Jan 23, 2020 2:54 am

Not unusual. AO and others made their DIC scope using a similar approach. I am not an expert on the physics although I have owned various ones. In the AO you adjusted for each objective to fine tune.

Per Olympus https://www.olympus-lifescience.com/en/ ... iguration/: This prism, often termed the objective or principal DIC prism, can either be matched to a specific condenser prism, or a single objective prism can serve to recombine wavefronts having the spectrum of shear angles represented by all of the condenser prisms. A majority of the microscope manufacturers configure their DIC microscopes to employ a single objective Nomarski prism, which is mounted in a rectangular frame that slides into the nosepiece (see Figure 4). In order to introduce bias retardation into the DIC optical system, the objective prism rides on a gliding support that can be translated back and forth across the microscope optical axis by means of a micrometer control knob.

Can or is this available motorized? Not sure but if it were I personally would avoid it. Just another potential malfunction that could result in a difficult repair as opposed to manual adjustment.

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ImperatorRex
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Re: Olympus AX/BX/IX DIC

#3 Post by ImperatorRex » Thu Jan 23, 2020 9:31 pm

microb wrote:
Wed Jan 22, 2020 11:23 pm
And does it need to be adjusted each time the turret is changed?
BX: If you change the objective you need to turn the condensor wheel on step further for the correct match of the DIC prism in the condensor. Since the condensor wheel-turret turns easily and smootly, I have not an issue with that.

microb
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Re: Olympus AX/BX/IX DIC

#4 Post by microb » Thu Jan 23, 2020 10:38 pm

My question is more along the lines of why the condenser gets different prisms for different magnifications but not the prism between the objective and camera.

einman
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Re: Olympus AX/BX/IX DIC

#5 Post by einman » Fri Jan 24, 2020 2:29 am

Follow the link in my response above and read the article on DIC. It explains set up and the theory. I believe you will find your answer.

PeteM
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Re: Olympus AX/BX/IX DIC

#6 Post by PeteM » Fri Jan 24, 2020 2:47 am

microb wrote:
Thu Jan 23, 2020 10:38 pm
My question is more along the lines of why the condenser gets different prisms for different magnifications but not the prism between the objective and camera.
The prisms in the condenser are fixed - each one provides a proper shear angle for a single or a narrow range of objectives.

The sliding prism above the objective turret provides a variety of shear angles as it slides from one side to the other. It could (and often does in other systems) be a series of fixed or slightly adjustable prisms above the objective. Just depends on the implementation.

viktor j nilsson
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Re: Olympus AX/BX/IX DIC

#7 Post by viktor j nilsson » Fri Jan 24, 2020 8:58 am

Regarding the case where there is single objective-side prism, but multiple condenser prisms, we discussed this in the photomacrography.net thread as well:
https://www.photomacrography.net/forum/ ... highlight=

In it, Ichty wrote:
The single [objective-side] prism is designed to match the exit pupils of all 3 (4) objectives it was intended for, Plan 16, Plan 40 and Plan 100 (+ Plan 6,3). The objectives were re-designed for this; some older Plan 40s are incompatible.
So to me,it seems that when you employ this strategy, you need to carefully design the objectives so that the their rear focal points are located at approximately the same positition. Based on my intuition, this may be relatively straightforward for higher magnification objectives, but more challenging for lower-powered ones (in a finite system).

Going back to the formula:
Image
where
fc: condenser focal length
alphaQ: condenser prism wedge angle
fob: objective focal length
alpha: objective prism wedge angle

...we have now set a constraint on alpha. Since fob changes with each objective change, we need to alther the condenser prism's wedge angle alphaQ or the condenser's focal length fc to satisfy the equivalance. This is what we accomplish by having multiple condenser prisms, or removing/adding condenser top lenses (or both).

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