Blak-Ray B-100 AP: Spectral Irradiance Chart

[JCDowdy]

There has been much recent discussion about the Blak-Ray lamp. Damon has provided one to be properly measured since the manufacturer has not made quality information available.

 

The plots below are NIST traceable absolute spectral irradiance, at a distance of 20cm in the center of the beam. The lamp was measured with an OL-756 double grating spectroradiometer, using a 20mm entrance aperture on the integrating sphere, 1nm wavelength increment.

 

On a linear scale the spectrum looks like others we have seen, prominent Hg line and little else discernible.

 

The same data plotted on a log scale however reveals what is underneath. Numerous fine Hg emission lines and the underlying contiguous continuous spectrum. Irradiance spanning just over 7 orders of magnitude also demonstrates the dynamic range of this research grade instrument. The Blak-Ray filter appears to be consistent with a thick industrial grade UV transmitting black glass with characteristic secondary transmittance band peaking ~760 nm.

[Damon]

Whoah! How cool!

Thanks so much John!

 

I have some idea but I am a dendrite in a sea of brains.

So of course I have to ask--

What does this mean for us--photography/filter wise et. al.?

 

How exciting!

 

-D

[colinbm]

Thanks very much John & Damon for providing this valuable information.

Col

[nfoto]

What the curve really means is that there is a continuous UV spectrum underlying the main peak and that this "extra" spectral information is just 2 to 3 orders of magnitude lower than the peak. Perhaps not enough to disturb short exposures in UV, but probably likely to influence longer exposures unless proper bandpass filtration is applied.

 

The visible light and IR seems to be kept as low as not to cause evident issues.

[colinbm]

Hi John

Is it possible to take a spectrum of the bare lamp please.

That will give us an idea of what the filter is having filter out.

Col

[JCDowdy]

When I have time, I will measure the bare spectrum as well as with various filters placed over the aperture of the sphere.

This should end the speculation (at least on my part :D) as to what is actually being blocked or transmitted as the case may be.

[Alaun]

Maybe it is helpful: I got a Blackray Model B 100 A for 230V, it came with a not working bulb, so I had to look for a replacement: It carries an Osram Sylvania H44 GS 100W bulb, maybe there is a spectrum somewhere around for these types of bulbs.

 

 

Werner

[Andrea B.]

Blak-Ray offers filtered & unfiltered spectral charts shown here:

Blak-Ray Lamps for Fluorescence Photography (almost done)

 

Of course, they are not as detailed as the nice graph that John has created above.

[Damon]

Thanks guys and gal for continuing to get to the bottom of this. We are likely to know more about these lights than anyone in the world. :D

 

Take a look at this: Spectrum looks weird but the bulb info. is interesting.

http://www.lamptech....vania%20H44.htm

 

-D

[JCDowdy]

Blak-Ray offers filtered & unfiltered spectral charts shown here:

Blak-Ray Lamps for Fluorescence Photography (almost done)

 

Andrea, please feel free to copy these plots over into that topic if you like.

[JCDowdy]

Take a look at this: Spectrum looks weird but the bulb info. is interesting.

http://www.lamptech....vania%20H44.htm

 

Damon,

That is a linear plot of the bare Blak-Ray lamp replacement bulb. You might peek inside one an check me on that.

 

Here is another unfiltered spectrum and pretty good data also from the same source but not in standard units. I re-plotted this data on a log scale and it has dynamic range indicative of a double monochromator but appears to be running a wider bandpass as evidenced by slight broadening of the Hg lines.

[Andrea B.]

I have summarized what has been found out about the Blak-Ray in a write-up linked below (which includes links to this thread, of course).

 

Again thanks to John & Damon for providing us with all this lovely information about the Blak-Ray B-100 AP.

 

http://www.ultraviol...vf-photography/

 

Comments, corrections, typos? Please do let me know.

[JCDowdy]

This spectrum and the discussion reminds me of earlier discussions about filter stacks.

 

I recall Bjørn or someone commenting on the level of NIR suppression one needed from a BG-type or S8612 filter for a clean UV-photo. I have searched for the specific posting but have not found it yet.

 

I specifically wish to check what was the recommended level of NIR blocking, was it 1E-3 or 1E-4 and was that transmission or transmittance?