Lasering GOBO's for high powered projectors

[Harry Radaza]

Anyone ever tried lasering GOBO's for high powered projectors. GOBO's (GOes Between Optics) are glass slides that goes infront of the lens to create huge advertisements on buidling walls just like this (http://www.kineticlighting.com/p_projection_advertising.php). We are planning on buying the projectors. However, the gobo's cost $120+ to get it customized from most manufacturers. I heard it was a laser process, so maybe my laserpro or universal can get the job done ?

GOBO's use dichroic (heat resistant) glass slides and heat resistant coloring on it. So lasering away the logo or text could produce the needed effect. Has anyone ever done this or can shed light on the whole process ?

[Joe Pelonio]

When in high school my son was a theater tech. He brought me one that was solid black, and I engraved an image of the moon that he used for a romantic scene in the school play. Worked nicely, but I can't help you with how the gobo was made. They were bought by the theater manager at a theatrical supply in Seattle. All I did was to cut a circle out of card stock the same size, place the glass in the circle, import the moon into Corel, center on the circle, and engrave. He said to keep it in the center 1/3 of the gobo, as there were some focus issues in this case.

[Richard Rumancik]

Harry, the projectors used for buildings seem to be different from the ones used in theatre. There isn't a lot of info about the nature/configuration of the "gobo" used for this special purpose projector. It seems they use some kind of strip gobo (4"x2" or 4"x4" images) that allows scrolling. Can you really project a 100 foot high image with one gobo? I suspect that multiple projectors are being used. Any idea of the cost of the projectors? They won't be cheap.

If you find out more info on this system, let us know. . .

For normal theatrical performances metal and glass gobos are used. The metal ones are like a stencil. The glass gobos allow color, plus you don't need supporting tabs (as used on metal gobos) to keep the gobo from falling apart. From my research, the glass ones seem to have a very complex photographic and chemical fabrication process. I am not sure how you would apply the laser to the fabrication of colored glass gobos; it is not obvious to me how the laser would be applied to this task.

Joe, you mentioned using the laser on a glass gobo blank. Do I understand correctly that you used the laser to ablate a black coating on the gobo blank? If so, this sounds like a suitable use of the laser, but of course it is only suitable for "monochrome" gobos (no color). But there is a possible market for these in normal theatre. Do you know what the black coating was on the glass? It sounds like you were able to etch it away sucessfully. (If you have any info on where the black glass gobos can be sourced I would be interested.)

[Mike Mackenzie]

Harry,

One of my first applications with the laser was Gobos. We were working with Disney and this was revolutionary technology at the time, this was probably 15-20 years ago.

I don't know if anyone has seen the light show that Disneyland puts on every night but these images are done using gobos created with the ULS system.

The first gobos were done using the uls co2 lasers and simply just removing the coating the tricky part was just to remove the coating and not mark the glass the coatings are only a few microns thick. To achieve the color they used to do color separation and etch the separated colors onto the same colored gobos. Then insert them into a tube and project them in full color.

The process now has changed to using a yag laser because it is easier to just remove the coating without marking the glass surface.

You can still accomplish this task using your ULS system however you will have to test the gobos to get the proper power settings. I will tell you this it is important to use high resolution (1000 dpi) so do your testing starting out with this DPI setting you will probably only be using 2-5% power of a 25 watt laser.

Here is a pic of one we did as a test several years ago.

[Joe Pelonio]

Joe, you mentioned using the laser on a glass gobo blank. Do I understand correctly that you used the laser to ablate a black coating on the gobo blank? If so, this sounds like a suitable use of the laser, but of course it is only suitable for "monochrome" gobos (no color). But there is a possible market for these in normal theatre. Do you know what the black coating was on the glass? It sounds like you were able to etch it away sucessfully. (If you have any info on where the black glass gobos can be sourced I would be interested.)
As Mike said I saw how thin the black was and used very low power, then had to make another pass to get it all off. It didn't affect the glass, it stayed clear and worked nicely in this case. They used another one that was sort of light yellow/orange behind it to give the moon color.

They did use metal ones too and asked if I could cut them but of course I couldn't. Like I said the gobo came from a Theatrical Supply in Seattle but he didn't have a name or address since the theater manager ordered them.

[Craig Hogarth]

How would you make the graffic? When you project on a tall building from the ground up, the prespective would be skewed, fatter towards the top?

I'm new to corel. Can corel figure this for you, or would you have to find mathmetician to calculate the dimensions?

[pete hagan]

We are an Apollo Gobo dealer and they use a photo / acid etching process to make the metal gobos not yag laser. Retail is 125.00 US for a one off but dealers can make you a better deal. http://www.internetapollo.com/

If you want any made I'll cut you the best deal out there at 15% above my cost plus freight but just for the Sawmill Creek group. I can't give my time away for nothing! Just PM me.



Pete

[Ricky Gore]

I know I'm late posting on this thread, but I'm new.. :)

I would like to know where to get Gobo Blanks and try this myself.

Very interesting. We use Gobos for corporate events every year.

Thanks,
Ricky

[Levi Chanowitz]

how much is the gobo projector? Can I use a regular light?

[Richard Rumancik]

Ricky, when this came up several months ago I tried to find out where to get the gobo blanks ("unpatterned gobos") as well. Joe had his blank supplied and did not know the source. I did quite a bit of searching but did not come up with much. I found one website (Drix Semiconductor) that will at least help you get the terminology right so that you know what to ask for. Unfortunately, they are in Belgium so I don't know how practical it is for you to import. I did not contact them. Maybe they have a NA distributor. With all the different types they sell, plus all the different projector (disk) sizes it could be a problem to get a reasonable quantity order.

www.drixsemi.com (http://www.drixsemi.com)

You will find the language you need to do web searches eg "borosilicate glass".

I found quite a few places in NA that will apply a custom pattern to borosilicate glass gobos, (usually chemical etched) but did not find distributors or manufacturers of the blanks themselves. They probably won't be willing to tell you where the disks came from . . .

You will need to educate yourself on the projectors, etc. There are many different gobo sizes. A book on stage lighting may elp. Some of the metalized gobo blanks are coated with photoresist for chemical (acid) etching rather than laser etching, so you need laserable blanks, not photo-resist coated blanks.

I have a binder full of info on gobos, projectors, etc but at the moment I am doing some R&D on making metal gobos. If you find a source for glass blanks in NA I would appreciate it if you could share it on the forum.

[Bill Cunningham]

I have found this.. It might be of interest..

http://www.derksen.ca/Gobotop.pdf

[Steve Clarkson]

Someone asked me to make one of these today. They have two different disks....a metal one and a glass one.

Does anyone make disks for GoBo's? Would black acrylic melt next to a 250 watt light bulb? Could cermark on glass work? Is there any material that we can cut or engrave that could take the heat?

[Dan Hintz]

With the high heat GOBO projector's put out, you need glass/metal... acrylic simply isn't going to cut it. I haven't tried Cermark on glass, but I believe it would work... if you can get the resolution you want (which shouldn't be hard).