Isn't this beautiful.

[Stefano]

The efficiency plot they show for your grating shows ~40% "absolute efficiency" at 500 nm. I don't know what that means, but I think your grating would work fine beyond 500 nm.

[colinbm]

In deed it can 'see' my RGB LED light....
 

 

[ulf]

6 hours ago, Stefano said:

The efficiency plot they show for your grating shows ~40% "absolute efficiency" at 500 nm. I don't know what that means, but I think your grating would work fine beyond 500 nm.

My guess is that the specified wavelength range is something like the FWHM, even if the shape is not at all bell shaped.

https://en.wikipedia.org/wiki/Full_width_at_half_maximum

 

As the curve tapers off more slowly towards IR the output might be usable further out there.

https://www.edmundoptics.com.au/document/download/492135

 

However there might be a mix in of second order diffraction components.

https://www.edinst.com/us/blog/second-order-diffraction/

[colinbm]

Thanks Ulf, the second order is why I didn't expect anything down there & is not why I got this UVC Grating, I want to test for UVC with a Mono converted camera soon.
I have just tried with a 850nm LED & saw no spectral line.

 

[dabateman]

On 12/22/2023 at 12:07 PM, Lou Jost said:

I wonder if the faint dark green broad band is the defocused 185nm line?

 

Edit: No, it looks more like an internal reflection, since the border is not straight.

Also his grating has a specification limit of 250nm. Which I may believe.  You need really pure glass to go lower.

The UV Nikon 105mm lens can also only see to a maximum of 230nm. 

So he will see UVC, just not less.

185nm is really hard and best in a vacuum box.

 

@colinbm

Try again with the UVC bulb and the full spectrum fp camera. But blow out the 365nm line completely,  or mask it. I am thinking you will need an exposure time of 30 seconds to 2 minutes, to see the 254nm line.

[Lou Jost]

On 12/24/2023 at 2:04 AM, ulf said:

My guess is that the specified wavelength range is something like the FWHM, even if the shape is not at all bell shaped.

https://en.wikipedia.org/wiki/Full_width_at_half_maximum

 

As the curve tapers off more slowly towards IR the output might be usable further out there.

https://www.edmundoptics.com.au/document/download/492135

 

However there might be a mix in of second order diffraction components.

https://www.edinst.com/us/blog/second-order-diffraction/

Yes. The efficiency curve for that grating shows about 10% even out to 1000nm.

[lukaszgryglicki]

The UV Nikon 105mm lens can also only see to a maximum of 230nm.

Isn't it 200 not 230?

But surely not 185.

 

[ulf]

1 hour ago, lukaszgryglicki said:

 

 

Isn't it 200 not 230?

But surely not 185.

 

If Nikon's spec is correct reaches a bit deeper than 200nm 

 

[dabateman]

On 12/26/2023 at 4:33 AM, lukaszgryglicki said:

 

 

Isn't it 200 not 230?

But surely not 185.

 

I maybe wrong again.

The official Nikon specification states 70% transmission from 220nm to 900nm. 220nm is the point of dipping, but where it ends exactly,  we don't know. A reliable person, with a correctly calibrated spectrometer would need to measure it to know.