Reminder: Flip that BaaderU

[Nate]

Thanks for the info, I have tried what I posted above, and you're correct. I saw the slightest of improvement in contrast, which appeared to me darker with the gold/ yellow side out/590nm/canon 40mm@ 1sec(too much leakage for me)

 

Tried with EL Nikkor 80mm(old metal)@wide open 5.6, and it took 3.5sec to see the leak with Baader/590mm. BUT........ popped in my 1.25 Antilia with astro adapter close to sensor with Baader screwed onto EL Nikkor 80, went up to 15 sec, and saw no leak at all. (The Antilia solo leaks IR and maybe some visible, but on paper goes lower than the Baader) 

 

Sorry for leading your topic away a bit, but I did learn something from all this, that Baader/Antilia gets better exposure time than ZWB1/Antilia, and since I can't see much bellow 340nm, this might work for me with no worry of any leaks. 1/20th sec, iso 400, at f8 early morning exposure.

 

Thanks for your topic, gave me some great info.

[ulf]

Most U- or UG-glass materials have there IR peak around 700nm. So also the Baader U. If there are one side as in you measurement that reflect the wavelengths in that area better, it is that to have facing outwards. This is exactly what you recommended.

[dabateman]

Well monkey see monkey do.  I finally connected that reflectance probe that came with my light source, it has six fiber end and a one fiber end leading to the probe.  I connected the six fiber end to my spectrometer and the one fiber end to my light source.

Here is my RAW Baader venus U data, not corrected and not all nice like Jonathan's data but looks similar.

 

Red side at 90 degrees using my grading 1 detector for UV to IR:

Green side at 90 degrees using my grading 1 detector for UV to IR:

Red side at 90 degrees using my grading 4 detector for Vis to IR:

Green side at 90 degrees using my grading 4 detector for vis to IR:

 

[Andy Perrin]

David, I don’t understand the setup here or what you mean by six fiber vs one fiber, or really anything else, including how to make sense of these plots. You need to make us a sketch of the setup. 

[dabateman]

Sorry Andy this is my probe:

The top section on right goes to the light source,  the six outer fiber section at bottom right goes to the detector.  The metal end probe on the left is held over the sample at a 90 degree angle from the surface. 

Light travels down the central core fiber to the sample. It then bounce off the filter mirror and is collected by the outer six fiber optics. This travels to the detector.  I have two detectors, one with grating 1, sensitive from 175nm to 800nm and one detector with grating 4, sensitive from 400nm to 1100nm. It has a long pass filter to block all light below 500nm. 

I don't see any reflectance with the AR coated S8612 filter I got from Steve.

Above are raw plots not corrected for the drop off in IR from my light source.  I am using a DT 1000 light source with tungsten and deuterium lights.

[JMC]

David, my probe is the same configuration as yours (6+1) but I used mine the other way round, with the 6 fiber arm going to the light source, and the single center one going to the spectrometer. Out of interest have you tried yours the other way around, and if so did you notice a difference?

[dabateman]

Interesting,  according to their video your right Jonathan.  They say for optimum performance you connect the single to the detector and 6 fiber end to the light.

 

I have never done it that way. Will have to see if there is a difference. 

 

Ok so after some reading,  I am throwing away sensitivity with the six fibers to detector.  Because I am not aligned to the slit.  A linear end of fibers, aligned to the slit should be used in the case where you have 6 to the detector. So for optium sensitivity it does make sense to have the 6 on light and 1 on detector. 

It also makes some comparative reference calculations easier too, as you will know the exact area of the reflectance spot.

[JMC]

No problem David. Thorlabs make the probes with the linear arrangement of fibers. I wonder how much of a difference they make in real life?

[ulf]

I don't think it will improve  the sensitivity very much, but might be wrong.

 

I tried fibres with different core diameter (single core, only) to gain S/N in another setup.

There were no difference in signal level between 600µm core and a 1000µm core.

I assume that the 50µm slit in my Flame spectrometer is around 500-600µm long.

[JMC]

Interesting Ulf. Makes sense. I tend to use 600micron cores in the fibers I get. I do have a 1000micron one, but just use that for lighting occasionally. The Thorlabs ones might be different though as they use 200micron fibers, so I could imagine lining up a number of those in the same orientations as the slit in the spectrometer could be useful over a simple bundle of of them.

[dabateman]

Both of my detectors have 25um slits that are 1mm. The JAZ can switch them, but they seem to be a rare part.

All my UV capable fibers are 600um. I will have to check this reflectance probe to see what the sizes are. I didn't order it, but came included with my light source. 

I got some 1200um fibers with a filter wheel, but they are only for IR and their sensitive is 10% of my other ones.

 

[dabateman]

I just found this table:

 

 

So my cable has a red band for 400um core diameter on the fibers and a white band for UV/vis.  These bands are on both the single and the six ends.

 

My bifurcating cable does have brown bands at the ends and its labeled by ocean optics as a 600um cable.  So I believe this table above.