Drilling a hole in a first surface mirror

[kecked]

Anyone have ideas on how to drill a 1mm hole in a first surface mirror? Due to size constrains I need to do this to sample a beam used for illuminating a sample. It’s a reference beam so I. Figured to sample through the back of a turning mirror. I have no other location in the light path to sample the beam or I’d use beam splitter or glass slide. So ideas on how to drill a hole in the glass without hopping the rest of the surface. I can’t just scrap the silver section I need an actual hole.

So far cracked one in half and peeled the coating in another. I’m Illuminati ing with a led so can’t use half a mirror either. Tried taping mirror too.

 

[WizardG]

Diamond burr, as fast as you can spin it (bidding starts @ 10k RPM), underwater. Use very gentle presure. Let the diamond grit do the work. Tape, or something, to mask the mirror surface for protection. Bset Idea I've got.

 

[RedCowboy]

 

[farbe2]

If you have access to a high powered pulse laser: try to burn the coating away.
You could also paint the location where you want to have the hole beforehand, this would make it easier to destroy the coating.

 

[kecked]

Fabre do you think I can just avoid the hole and remove the coating to grab a reference signal? I was just afraid of back scatter from the return signal. What I have is light enters a telecentric lens. This hits the turning mirror and is reflected back from the object set at normal incident. I’m imaging this on a CMOS camera on the telecentric lens to measure reflectance. So I wanted to add a reference to the system for the led. Hence the hole. I could not find a space to put a beam splitter except this turning mirror and I figured if I capture light from the telecentric lens before it turns up I can avoid also grabbing the return reflection. I’m measuring 0.01% changes in intensity.

Unfortunately I won’t really know if I and getting the return reflection too without a hole.

So I have a 355nm 12kw 1khz laser. I could ablate the coating but doubt pop a hole . You know I might need to just use a blank and drill it and then coat it after. I’m only looking for 1mm hole or less. I’m using it like a spatial filter as well. Thinking to add a polarizer set as well as I may be doing MOkE later with a magnet.

I’m an idiot…..use a 90/10 beam splitter. Never mind. I have plenty of illumination light.

 

[farbe2]

I’m an idiot…..use a 90/10 beam splitter. Never mind. I have plenty of illumination light.

Even a "bad/cheap" mirror could work, as long as it got a polished back side.
Depends on how much light you actually need.

 

[kecked]

Here is what I settled on. A dichroic mirror high pass . I have 7nm filter on the camera so I just reflect the band I need and pass the rest. The led brightness should be linear releative to all the wavelengths. No holes!