Math Check - Audience scanning - help?

[demolish50]

I've been toying around with the safety scan lens a bit in my home. That thing is pretty damn cool. I really like it with the static beam around 10-12mW/cm², which I can get in a really short distance out even with a watt coming out of the projector, 10 meters or so. Your right, I could not imagine 10x. I don't have a fancy irradiance meter or anything, just that Radiant X4 so my numbers might not be perfect but I think they are close.

The only complaint I have is the stray "ghost" beam or two that will come out of the lens for some reason. I just can't seem to get the angle perfect.

[buffo]

The only complaint I have is the stray "ghost" beam or two that will come out of the lens for some reason. I just can't seem to get the angle perfect.

How did you attach the lens to your projector? Are you using the special Pangolin mount? It will give you 3 axis' of movement, allowing you to get the alignment perfect. Without this mount, getting the lens aligned is a nightmare.

Adam

[demolish50]

How did you attach the lens to your projector? Are you using the special Pangolin mount? It will give you 3 axis' of movement, allowing you to get the alignment perfect. Without this mount, getting the lens aligned is a nightmare.

Adam

Yeah I'm using their mount but but it just seems like there is always a ghost. It seems like dead center has "ghosting" on both x and y that extend past the center point equally. If I go either way it just gets bigger one direction and smaller the other. I hope I'm explaining that right. I've spent hours trying to get it perfect...I'll have to take a few pics one day and show you what I mean. TBH I'm content with, when your viewing a beam show its not really noticeable.

[m0f]

There will always be some ghosting in my experience, but when setup perfectly the ghosting will follow / be aligned well with the scanned effects and so much less visible.

One thing I must add just to clarify regarding using a 2.25 sq/cm as the aperture size on your sensor and calculating your mpe based those measurements, is that your laser dot MUST completely fill or be greater than the size of the sensor in order for that to work. If not, use a smaller aperture over the sensor to measure. But if for example the beam is smaller than the sensor area, then you could potentially be at way higher power density than calculated / measured.

You may indeed already know this, but didn't mention it in your post so I just wanted to stress the importance just in case of a potential misunderstanding. In my experience you much be quite far away and using a high powered safety scan lens in order to get a beam that large so for taking measurements in smaller rooms it may be much more feasible to make a smaller aperture for it

[demolish50]

Yes I did

"assuming the entire sensor area is full and a static beam at the closest point of my"

With the -6 my beams are that big at around....I dunno 1.5 meters? I have not measured....at 5 meters they are huge...inches.

At 5 meters the white balance is screwed. Since the blue has a different profile then the red/green and the lens really amplifies it at that range I have a smallish green circle, followed by a larger red circle, followed by an even bigger \\ blue shaped beam. Again not really noticeable viewing a show just when toying around.

At the aperture, supposed to be 1mm green, and 1-2mm for the red/blue. I'm not sure how to measure that yet TBH.

Also it seems my numbers are very close to what Bill presented in is video where he discussed the safety scan lenses. Not exact but close enough to make me feel good but if I'm doing something wrong I want to know like know so thank you for double checking me.

[m0f]

For sure. I found the initial beam size makes more of a difference than anything else in how much they expand with the safety lenses. Matching up initial beam sizes with a beam expander / telescope very much improves how they match up under the safety lenses. Initial beam size makes way more of a difference than initial divergence or other properties.

But either way is surprisingly not as noticeable when watching a show that would be expected. Even at very large distance with smaller diopter lenses. Only time it really shows up is in still frame pictures.