ballen
Diamond
- Joined
- Sep 25, 2011
- Location
- Garbsen, Germany
I recently picked up a "projection measuring microscope" that was advertised as a Deckel accessory. It was cheap enough that I bought it out of curiousity, though if it works I might find some use for it.
The device consists of a substantial vertical tube, containing lenses. These direct light from underneath up to a angled mirror, which direct the light away from the operator. It then bounced off another angled mirror, which directs the light towards the operator, and onto a screen. The screen is marked with some lines and angles and can be easily rotated.
The whole device was covered in grime and the screen did not rotate - it was frozen in place. I took it apart, cleaned the optics, and freed the screen. One interesting thing was that inside one corner of the cabinet was a hardened pool of a yellow-white substance which had the consistency of hard wax or pitch. I had the impression that over 30-50 years (I can not tell how old this is) that material may have flowed from another part of the device and pooled there. You can see it in the bottom right-hand corner here.
My first question: Does anyone know what this waxy white stuff might be?
My second question concerns the screen itself. This consists of three glass plates. The innermost one is fixed and transparent, and has scribed lines at 1 degree separations on the circumferance. The second and third plates are "glued" together and have crosshairs and some curved lines marked as 0.4, 0.8 and 1.2 mm. They are held in a rotating mount, and are about 175mm in diameter. This is what the user looks at. I have the impression that these two plates have something "cloudy" in between them to act as a projection screen. It's not in the best of shape. In fact I wonder if the "pitch" was once in between these plates and flowed out. Can someone tell me how this part of the device might have been made? What is the material which is normally used as a "see-though" screen? I can probably soak the glass plates in alcohol or acetone to separate them, if needed, to renew what was between them. I know that one can purchase "diffusion film" which is used for rear-projection screens. Perhaps I can use that.
Last question: are these devices meant to be used with even illumination behind the work, so one sees a shadow of the work? Or are then meant to be used with light reflected from the work, so one sees the surface of the work?
I can post more photos if that would be helpful.
Cheers,
Bruce
The device consists of a substantial vertical tube, containing lenses. These direct light from underneath up to a angled mirror, which direct the light away from the operator. It then bounced off another angled mirror, which directs the light towards the operator, and onto a screen. The screen is marked with some lines and angles and can be easily rotated.
The whole device was covered in grime and the screen did not rotate - it was frozen in place. I took it apart, cleaned the optics, and freed the screen. One interesting thing was that inside one corner of the cabinet was a hardened pool of a yellow-white substance which had the consistency of hard wax or pitch. I had the impression that over 30-50 years (I can not tell how old this is) that material may have flowed from another part of the device and pooled there. You can see it in the bottom right-hand corner here.
My first question: Does anyone know what this waxy white stuff might be?
My second question concerns the screen itself. This consists of three glass plates. The innermost one is fixed and transparent, and has scribed lines at 1 degree separations on the circumferance. The second and third plates are "glued" together and have crosshairs and some curved lines marked as 0.4, 0.8 and 1.2 mm. They are held in a rotating mount, and are about 175mm in diameter. This is what the user looks at. I have the impression that these two plates have something "cloudy" in between them to act as a projection screen. It's not in the best of shape. In fact I wonder if the "pitch" was once in between these plates and flowed out. Can someone tell me how this part of the device might have been made? What is the material which is normally used as a "see-though" screen? I can probably soak the glass plates in alcohol or acetone to separate them, if needed, to renew what was between them. I know that one can purchase "diffusion film" which is used for rear-projection screens. Perhaps I can use that.
Last question: are these devices meant to be used with even illumination behind the work, so one sees a shadow of the work? Or are then meant to be used with light reflected from the work, so one sees the surface of the work?
I can post more photos if that would be helpful.
Cheers,
Bruce
