Introduction . . .

This is a brand new blog, by a brand new blogger. However, some readers may recognize this blog's title, taken from a series of books of the same name. Unfortunately, time has a way of gradually making printed material all too quickly outdated -- especially these days -- and so, this blog was created partly as an attempt to address that issue.

As we move forward from here on-going efforts will be made to transfer selected content from the Better Microscopy books series into this new format, not only to provide to provide more effective distribution, but also as a means for making timely additions and overdue updates to that material. In addition, much previously unpublished material is now planned to be released, including high-resolution color images.

The current plan is to aim for a content mix that is both interesting and educational -- perhaps even inspiring -- and which will address the needs and interests of a wide range of user levels, from beginner to semi-professional. With more decades of Microscopy experience than I care to admit, I hope I will be able to contribute something to others in terms of both knowledge and enjoyment.

I hope you find something of interest in new undertaking as it takes shape and gain much from its content, now and well into the future!

Just beware of the occasional attempts at humor...

Thanks for visiting!

Saturday, February 25, 2017

Variable-color Phase Contrast ?

AO seems to have dropped the ball with their Polanret Variable Phase Contrast system – too complicated, too expensive, and (for many users) just too hard to understand! Yet AO was not the first maker to venture into the 'variable-phase' waters…

Way back in the late 1960's Nippon Kogaku (Nikon) introduced a "polanret" type system of their own, intended for use on their Model "S" series of stands. However, unlike the later AO system the Nikon system was simple, compact and rather affordable. It also distinguished itself by creating user-controllable interference colors in the phase images!

And, apparently just to ensure that potential users had no idea what it was, they called their marvelous new creation, Nikon "Interference Phase Contrast" (or, more simply, "IPC"). Not even a hint of "Color" anywhere in the official name…!

Now, like the AO system, the Nikon IPC system did not require special objectives but relied on the standard Nikon Achromat types of the day. And, this was probably its Achilles Heel – the excellent Nikon Plan, Fluorite and Apo objectives were simply not supported!

Thus, Nikon offered an expensive accessory that could not be used with Nikon's own highest-quality optics, only with their  lower-end "classroom" type Achromats. What were they thinking…?

But inability to use quality optics was not the only flaw. Since most of their S-series scope had somewhat limited illumination capabilities (the S-Kt and S-Ke models were exceptions), the system relied upon extra-wide openings in its condenser in order to compensate for the light loss within the system. This was coupled with the use of rather generous phase-ring widths in the optical head, a step quite likely taken to simplify system adjustment by allowing a little more "slop" in the optical alignment.

While these measures did allow the system to be used on the lower-cost models, and by relatively unskilled users, it also placed some limitation on the ultimate quality of the resulting phase images.

That said, this is not meant to imply that the Nikon system provides unsatisfactory images – far from it! (See inset detail in the sample image below – click on image for larger versions:)

In fact, with very little effort it is possible to create a wide range of very colorful and highly-detailed phase contrast images using the system. (See end of this post for additional sample images.) In fact, it may be more correct to classify the Nikon IPC system as "artistic," rather than as a primarily "scientific" device.

Now, compared to the rather monsterous AO Polanret system (which weighed in at nearly 15 lbs!) the compact Nikon Interference Phase Contrast system is a marvel of Japanese optical and mechanical technology and innovation. The basic unit, responsible for the phase contrast and interference color functions is less than 10 inches long and sits comfortably (and horizontally) atop nearly any Nikon S-series biological microscope. The matching Interference Contrast condenser is simply a basic Nikon S-series phase contrast condenser with special, extra-wide ring openings, matching those in the optical head.

Control is much simpler than on the AO Polanret unit with a simple horizontal slider-bar holding a set of phase rings and a pair of control knobs to set the optical parameters. Using these the user can set the equivalent of either Bright or Dark contrast, as well as a wide range of contrast amplitudes. (Essentially, one knob selects the background color while the other chooses the level of contrast, although there can be some limited interaction between them at extreme settings.)

One additional, but very important distinction between the AO and Nikon systems is, as one might well expect, that while the AO system is intended for "infinity" type objectives, the Nikon system (naturally) is intended for use with "finite" (or, "160mm") objectives.

Perhaps because of this the Nikon system seems far more amenable to adaptation for use with more modern optics than the simple 1960s-era Achromats for which it was designed. In fact, with little effort the Nikon IPC system functions very well with some of Nikon's best Plan objectives, including many of the CF and CFN Plan Achromats. (And its use is not limited to the old, black S-series either, as it works quite well on a number of more more stands as well, including even some non-Nikon scopes, such as the Olympus BH-series – assuming a proper mounting adapter is used.)

Note that the images below were created simply to demonstrate some typical IPC system image color possibilities and so may not be truly representative of its resolution capabilities
  (Click on image set below for larger versions.) 

Note that focus has been altered very slightly between above images to emphasize different details. 

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