Can we use Mitty NIR ?

[Adalbert]

Hello everybody,
Does anybody know if the Mitutoyo M Plan APO NIR can be used for the photography with the visible light?
According to the specification it is optimized for the frequency between 480nm and 1800nm.
But what about the range between 350nm and 480nm? Is it blocked?
BR, ADi

[Lou Jost]

My guess would be big blue/purple CA.

[typestar]

My guess would be big blue/purple CA.

Hi Lou,

do you meant this "big blue/purple CA" for the range outside the specification or do you mean this for the complete objective?

"Mitutoyo’s NIR, NUV, and UV infinity corrected long working distance objectives combine the benefits of the standard M Plan Apo ... series objectives with enhanced spectral ranges.
The NIR objectives are corrected from 480 to 1800nm"

I think, as we see in almost doubled price of the NIR lenses,
https://www.edmundoptics.de/p/10x-mitut ... tive/6833/

despite the only little lower NA of 0.26 in special the spectral range is enhanced, so for the work in visible light it should at least behave with the same power of a "standard" Mitu M Plan Apo... (?)

@Adalbert: For the spectral range lower then 480 Mitutoyo offer their NUV objectives --
https://www.edmundoptics.de/p/10X-Mitut ... ive/28634/ for almost 4 times the price of the normal 10x M PLan Apo...

All the best,

christian

[Lou Jost]

"do you meant this "big blue/purple CA" for the range outside the specification or do you mean this for the complete objective?"

Christian, assuming the illumination is white light, there will likely be blue-purple CA. The specs say the lens is not apo corrected for wavelengths shorter than 480nm, and that is visible blue light.

Yes, the spectral range is bigger than that of the ordinary Mitutoyo lenses, but the range is also shifted toward the IR end of the spectrum. That leaves the blue end uncorrected.

[typestar]

...
Yes, the spectral range is bigger than that of the ordinary Mitutoyo lenses, but the range is also shifted toward the IR end of the spectrum.

Lou, if I try to read it critical AND if the wording in the Mitu description is not just plain / fooling advertising --
for "our" normal use of light in macrophotograpyh: should a NIR lens not work there at least as good as a "normal" Apo corrected Mitu in this range.
and also be usefull for longer wavelength?
And would the extended APO correction -- if really corrected up to this large scale in the range -- not justify the much higher price -- with a little lower NA...

just my thinking,

all the best: christian

[Lou Jost]

No, for the reasons I just gave. The specs clearly say it is not corrected for blue light.

[typestar]

No, for the reasons I just gave. The specs clearly say it is not corrected for blue light.

Lou, perhaps I said it not clear enough: I'm, for myself, not interested in the near UV correction / blue light at all and did not point to the correction of the blue light. I just wanted to explain, that the lens
with a range from (wavelength 480 to 1800) should work correctly in a "normal" work for us as the M Plan Apo (wavelength 435 - 655)... Or am I wrong?

[Lou Jost]

Christian, maybe we are miscommunicating. The answer is "No". I will say it again in a different way:

The specs clearly say that the lens is NOT apo corrected over the whole visible spectrum. It is corrected for 480nm-1800nm. In contrast, the wavelength range of the normal 10x apo is 435nm-655nm. So while the NIR lens has a much wider spectral range, the range does not cover the blue portion of the spectrum.

That means there will be blue or purple fringes when this lens is used with white light. I don't know how bad they will be, but there must be a reason why Mitutoyo gave those specs.

By the way, there is nothing at all misleading in Mitutoyo's advertising about this lens. There's no contradiction between having an enhanced spectral response and shifting the range towards one end of the spectrum or the other.

[Lou Jost]

Just to be clear, when using an objective normally, there is almost always a blue component at every pixel of the image. So even if you are imaging white things, you'll see blue fringes with the NIR lens. 480nm is NOT in the UV range so I don't understand your comment about that.

[typestar]

Christian, maybe we are miscommunicating. (...)

The specs clearly say that the lens is NOT apo corrected over the whole visible spectrum. It is corrected for 480nm-1800nm. In contrast, the wavelength range of the normal 10x apo is 435nm-655nm. .... I don't know how bad they will be, but there must be a reason why Mitutoyo gave those specs.

Thankyou Lou, yes I think we are miscommunicating or I was misleading in my points...
The question would be, HOW far / bad / strong would the missing range of this 45nm (from 435nm to 480 nm) influence the picture, if the rest (from 480 nm to 655 nm) is well apo corrected in the NIR objectives...
And with the NUV objectives -- (which are optimized from 355 bis 620 nm) -- there the upper 35nm of the wavelength - compared to the normal M Plan Apo is missed -- would the NUV lenses - in that concern -- be less critical? As I know that some users here work(ed) with Mitu NUV lenses

Thankyou again for your thoughts

[JohnyM]

To answer that question, one would need to find color focal shift response graphs, or at least know lines that objective is corrected for to estimate from theoretical.
Ie:
https://www.thorlabs.com/images/TabImag ... G1-780.gif

I've wrote about that if you're interested:
http://www.photomacrography.net/forum/v ... ht=#238705

Guessing part:
It seems like NIR is "skipping" g and h lines. In that case i would expect to see very mild blue fringing and moderate purple fringing. Probably comparable to PlanFluor (i know you had one, bought it from you ) results in this spectrum.

Looking ad UV version, it seeems like a clear improvement over MPlanApo. But if MPlanApo is correcting for h line (and i belive it is) it would yeald no improvement outside UV imaging, for quite a lot of $.

[Adalbert]

Hi guys,
OK, the problem would be the CA, blue or purple fringes, Apo correction for the short waves.
But what has been the experience of someone who has already used such lens with the white light ?
BR, ADi

[JohnyM]

Not mitty NIR, but other dedicated IR optics interests you?
Reflachromat (mirror objective) yealds absolutely unusable image in VIS. 0 contrast, CA free tho! Only way i could make it produce an usable image is when mounted to dia microscope with IR pass filter.

There are many more aspects that this kind of optics may have to consider. VIS reflective coatings as an example.

I guess only way for you to know is try objectie you're interested with. Or ask Mitutoyo, but i doubt the answer to be different from "It's not VIS optics".

Best case scenario: it will work just like MPlanApo, but with some violet fringes.

[Adalbert]

Hi Johny,

to dia microscope with IR pass filter

I have already been thinking about the IR illumination :-)
BR, ADi

[JohnyM]

Not worth anything, unless you're scientist and you know what you're doing. IR "effect" is 2 clicks in photoshop of R chanell.
Other effect is depth penetration of light rays. But that's not desirable for epi illumination stacking.