Jump to content
UltravioletPhotography

Curiosity killed the cat (Fluorescence of urine marks)


Recommended Posts

Reference: http://www.ultraviol...of-urine-marks/

 

Just to get one thing out of the way before someone complains: No animal, especially no cat was harmed before, during or after these images were made. The title was chosen because it came to my mind when we discovered the urine marks with the newly acquired UV-torch.

 

Cats are among the most popular pets, regardless of the fact that they can show different sorts of behaviour that are not always welcome, to put it carefully. …. I just want to mention scratches on furniture, rodents and other prey brought into the house and urine marks that especially male cats use to mark their territory. Nevertheless, I admit that I kind of like our cat despite these annoyances.

Depending on where these urine marks are left they might be visible after drying. However, in the case shown here, the wall looks absolutely normal to the human eye:

 

Visible light image: Panasonic Lumix GH2 with Leica Marcro-Elmarit 45 mm, f2.8.

post-14-0-29455300-1382383808.jpg

Image reference: CHA_P1210496_131005

 

Taking an UV-image of the same spot does show something: The dry urine is less UV-reflective than the rest of the wall and so it gets visible because these areas look a bit darker than the surrounding wall.

 

UV-image: Panasonic Lumix G1 broadband modified, Noflexar 35mm, f3.5, with Baader U-filter 2” and UV-flash MR21.

post-14-0-97329200-1382383804.jpg

Image reference: CHA_P1110452_131005

 

However, if the wall is illuminated with UV-light in the dark, the traces of urine show a bright blue fluorescence, which stands out much more than in the capture of the UV-reflection.

 

UV-induced visible fluorescence: Panasonic Lumix GH2 with Leica Marcro-Elmarit 45mm, f2.8, with the B+W 415 UV-cut special filter and the Baader UV/IR-cut filter mounted in front of it (to reduce the IR-amount coming from the flash). UV-flash MR21.

post-14-0-37592900-1382383810.jpg

Image reference: CHA_P1210502_131005

Link to comment
The lawyer of the cat says that this evidence only proves that someone has left a mark. It doesn’t prove who has left it …
Link to comment

If there is just a single cat in the household that would be strong circumstantial evidence ....

 

By the way, such amount of deposited urine surely must make a smell?

Link to comment

Well, we had two cats before one was killed on the road a few months ago, before I had an UV torch.

 

You can certainly smell if there is a fresh mark somewhere. Luckily the smell disappears pretty soon.

 

This mark was left in an area of the house where the cats are not supposed to be at all. However, if someone leaves a door open they might get in and then they seem to be tempted to mark the “new” territory. .After that discovery we became a bit upset and examined the entire house with the UV torch. Fortunately, there were no such markings in other rooms where the cat(s) were/is allowed to be …

Link to comment

Curiosity killed the cat -

but Satisfaction brought it back.

 

And I'm laughing about "the cat's lawyer". :D Too many CSI shows!!

 

Good entry for the UV Forensics section.

Link to comment

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
×
×
  • Create New...