Starting to look at optics for the first time in depth, and have IR compatibility question

[jd22981]

Hello all,
I'm finishing up a few of my first builds and I'm about to start investing into reloading equipment and optics in the near future. I'm a firm believer in the buy once cry once school of thought.
I've looked at quite a few reviews online and compared some of the top brands, but I came across some of the IR sights and a few questions have come to mind. I have found a few IR sights where the manufacturer makes them to clip on in front of existing scopes. The effect of it is that the existing sight is essentially just zooming in on the IR optic's screen, which has limitations. I understand that regular glass doesn't allow IR light to pass through, so a clip on IR optic wouldn't be able to be added behind a traditional scope.
I've read that there are other types of lenses that aren't the traditional type of glass material that will allow IR light to pass through, which would allow a IR sight to be added behind them. The result is that as long as the existing sight is sighted in the IR clip on can just be thrown on without the need for additional sighting. It would also allow for the existing optics capabilities to be used without the limitation of zooming in on a screen.
The info I've read on this hasn't actually referenced any specific manufacturers of such optics though. I'm not in the market for an IR sight yet, but because I think it will be something I invest in down the line, I'd rather look into having IR compatible optics now with this special type of glass.
Is anyone aware of which optics or manufacturers of such optics are out there?
Thank you

 

[Lowdown3]

"IR sights"- do you mean a clip on night vision device?

Trying to understand your question better.

 

[CoryT]

Twp types of devices out there, I2 and Thermal.

I2 devices amplify light and display an image on a phosphor screen. They require some amount of light in the visible to near infrared spectrum to function, they do not work in total darkness. They can be had in a clip on weapon sight and can be used (in limited fashion) behind a day optic.

Thermal devices see heat, infrared outside the visible spectrum, called blackbody radiation that is emitted by all matter as a result of its temperature. This IR radiation is blocked by many normal materials that visible light is not, such as glass, plexiglass, flourite and other transparent materials. Lenses in a thermal system are often made from Germanium, which can be ground and polished to make a lens that will focus this IR to make an image. The sensor and processor in the device once again display an image to the user or some type of digital screen, such as LCD. These cannot be placed behind a day optic as the IR radiation used does not pass though normal optical glass and so must be either a clip on in front or a dedicated weapon sight with it's own aiming reticle.

A sight with Germanium lenses would be useless for normal daylight use, as visible light does not pass through it. Day/Night thermal systems have two separate optical channels, one for visible light and one for the thermal viewer. You cannot have a day optic that will mount a thermal device on the ocular.

 

[jd22981]

"IR sights"- do you mean a clip on night vision device?

Trying to understand your question better.

I meant thermal rather than I2 as CoryT differentiated in his post.

Twp types of devices out there, I2 and Thermal.

I2 devices amplify light and display an image on a phosphor screen. They require some amount of light in the visible to near infrared spectrum to function, they do not work in total darkness. They can be had in a clip on weapon sight and can be used (in limited fashion) behind a day optic.

Thermal devices see heat, infrared outside the visible spectrum, called blackbody radiation that is emitted by all matter as a result of its temperature. This IR radiation is blocked by many normal materials that visible light is not, such as glass, plexiglass, flourite and other transparent materials. Lenses in a thermal system are often made from Germanium, which can be ground and polished to make a lens that will focus this IR to make an image. The sensor and processor in the device once again display an image to the user or some type of digital screen, such as LCD. These cannot be placed behind a day optic as the IR radiation used does not pass though normal optical glass and so must be either a clip on in front or a dedicated weapon sight with it's own aiming reticle.

A sight with Germanium lenses would be useless for normal daylight use, as visible light does not pass through it. Day/Night thermal systems have two separate optical channels, one for visible light and one for the thermal viewer. You cannot have a day optic that will mount a thermal device on the ocular.

Thanks for explaining that CoryT. I meant thermal rather than I2. I had read about germanium a little while back but couldn't remember the name for it. What I read had discussed how it allows the thermal spectrum to pass through and that it is used for thermal imaging because commonly used optical materials don't allow that portion of the spectrum to pass through.

I didn't realize that germanium, although allowing the relevant portion of the thermal spectrum to pass through, doesn't allow our visible spectrum to pass through. That led to me believing that certain day scopes could be constructed from germanium rather than typical glass, facilitating a rear thermal clip on device. Thank you for clearing that up though.

The idea of a front clip on being zoomed in on by a daytime optic doesn't seem that appealing to me. I'm going to have to rethink this. Thanks again for clearing that up.

 

[shoobe01]

The idea of a front clip on being zoomed in on by a daytime optic doesn't seem that appealing to me. I'm going to have to rethink this. Thanks again for clearing that up.

But: works great. I have used NOD*-behind, dedicated NV scopes, and clipons and... there's a reason it's become the go-to method. I'd see if you can get to a class, demo, hunt-with-loaners, or just see if you can rent one (yes, all these exist) to try it out first.

FYI:
"I2" also can be called II (Image Intensifier, same thing abbreviated differently as I2) NOD (night observation device) or NV (Night Vision). Night vision image intensifiers are only that. They /incidentally/ see into the NIR (Near Infra-red) but that's not the purpose and older units saw much less IR. The NIR band doesn't see heat, but just more like how UV is just a bit over the end of the violet end of the spectrum, NIR is just more-red, but not that far.

Thermal (also TIC: Thermal Imaging Camera), is available in MWIR (Mid-Wave Infra Red) or LWIR (Long-Wave...). For our purposes, both see heat the same way, but MWIR is much more susceptible to being blocked by rain, dust, fog, smoke, etc. Nothing to do with (rumors abound!) temperature of the stuff in the air, just frequency; think faraday cage, regularly-spaced items at a multiple of the frequency you work at. To nerd out more: There are a bunch of bands in the middle there we don't use because they don't see through things like /air/ due to frequency issues. But, it's not critical in all situations.

Also be aware for modern micro-bolometer (like the CCD on a digital camera, the sensor technology used today) units, there's a resolution of the sensor AND of the display screen and... so on. Many specs. Read up a lot and understand what you are getting, and try it out if you can indeed.

 

[jd22981]

But: works great. I have used NOD*-behind, dedicated NV scopes, and clipons and... there's a reason it's become the go-to method. I'd see if you can get to a class, demo, hunt-with-loaners, or just see if you can rent one (yes, all these exist) to try it out first.

FYI:
"I2" also can be called II (Image Intensifier, same thing abbreviated differently as I2) NOD (night observation device) or NV (Night Vision). Night vision image intensifiers are only that. They /incidentally/ see into the NIR (Near Infra-red) but that's not the purpose and older units saw much less IR. The NIR band doesn't see heat, but just more like how UV is just a bit over the end of the violet end of the spectrum, NIR is just more-red, but not that far.
View attachment 7740547

Thermal (also TIC: Thermal Imaging Camera), is available in MWIR (Mid-Wave Infra Red) or LWIR (Long-Wave...). For our purposes, both see heat the same way, but MWIR is much more susceptible to being blocked by rain, dust, fog, smoke, etc. Nothing to do with (rumors abound!) temperature of the stuff in the air, just frequency; think faraday cage, regularly-spaced items at a multiple of the frequency you work at. To nerd out more: There are a bunch of bands in the middle there we don't use because they don't see through things like /air/ due to frequency issues. But, it's not critical in all situations.
View attachment 7740549

Also be aware for modern micro-bolometer (like the CCD on a digital camera, the sensor technology used today) units, there's a resolution of the sensor AND of the display screen and... so on. Many specs. Read up a lot and understand what you are getting, and try it out if you can indeed.
View attachment 7740548

Shoobe01, nerd out all you want! I love science!
I'm kind of familiar with night vision because of my hunting trail cams and the differences between 940 and the 800 frequency. I can relate it to that. Although don't know much about it beyond the use of my trail cams.
I have never use thermal, but didn't realize I renting or demoing is a possibility. Unfortunately, having just moved to the upstate of SC I don't know anyone around here, let alone anyone that has either of the two technologies. There are a few stores that I will be checking out in the near future. I still have to find a decent outdoor range.

 

[shoobe01]

Shoobe01, nerd out all you want! I love science!
I'm kind of familiar with night vision because of my hunting trail cams and the differences between 940 and the 800 frequency. I can relate it to that. Although don't know much about it beyond the use of my trail cams.
I have never use thermal, but didn't realize I renting or demoing is a possibility. Unfortunately, having just moved to the upstate of SC I don't know anyone around here, let alone anyone that has either of the two technologies. There are a few stores that I will be checking out in the near future. I still have to find a decent outdoor range.

Most places that rent (and I haven't done it in forever so don't know any to suggest right now, but google may be your friend) are mail places. They will fedex you the unit. Often this is a try-before-you-buy so if you love one, you keep that and toss your card down, return others, etc. Know people who did this, if lost after a few weeks, DM me and I'll see if I can find some names from those I know).

NOD sales are not usually top of the list in the marketing, so check around your local gun stores, one may have a cabinet of night/thermal units in the corner, and if so they likely then will also be tied into their distributor, can get you on the list for when there are demo days, etc. Similarly: check ranges for their event calendars; gun, and optics makers make roadshows with their stuff, maybe one of yours will be a stop and you can try some out, plus get free pizza

 

[jd22981]

Most places that rent (and I haven't done it in forever so don't know any to suggest right now, but google may be your friend) are mail places. They will fedex you the unit. Often this is a try-before-you-buy so if you love one, you keep that and toss your card down, return others, etc. Know people who did this, if lost after a few weeks, DM me and I'll see if I can find some names from those I know).

NOD sales are not usually top of the list in the marketing, so check around your local gun stores, one may have a cabinet of night/thermal units in the corner, and if so they likely then will also be tied into their distributor, can get you on the list for when there are demo days, etc. Similarly: check ranges for their event calendars; gun, and optics makers make roadshows with their stuff, maybe one of yours will be a stop and you can try some out, plus get free pizza

Sounds good and thanks for the feedback. It's going to be a few months till I will be in a position to make a purchase, so I'm just getting ideas now. I think February or March I should have enough saved up for something decent. I want an Nvision, but think a Pulsar would be more around my price range. I can't wait to check a few out

 

[thelaststraw]

Check in the training sub forum. CR2 is doing a night/thermal class in your part of the states if I remember right. I want to say GA or Virginia, can't remember offhand. It's solid advice about try before you buy. There is definitely a learning curve to the different setups.

 

[jd22981]

Check in the training sub forum. CR2 is doing a night/thermal class in your part of the states if I remember right. I want to say GA or Virginia, can't remember offhand. It's solid advice about try before you buy. There is definitely a learning curve to the different setups.

Somehow I completely overlooked the training forum. I'm checking it out now. Thank you

 

[thelaststraw]

The specific manufacturer that they partner with may not have devices that are what you are needing. The instructors however have plenty of time behind thermals and nods, I'm sure they could be of assistance. I'm glad to help, it won't happen often as I'm pretty new in everything around here.

 

[jd22981]

The specific manufacturer that they partner with may not have devices that are what you are needing. The instructors however have plenty of time behind thermals and nods, I'm sure they could be of assistance. I'm glad to help, it won't happen often as I'm pretty new in everything around here.

Any help is always appreciated. Thanks Thelaststraw