P3D Heat Study part 4 of 7 (Observations)

[Tom Hubin <thubin@xxxxxxxxx>]

Hello,

Here is part 4 of 7.

Tom Hubin
thubin@xxxxxxxxx
AO Systems Design

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        Some Observations

        PSSP's projector #1 is a TDC116 with SN 84086. It has a pair of 
        3mm thick, light turquoise blue, infrared filters. The glass 
        type is unknown but the projector has destroyed some film and 
        plastic mounts due to excessive heat at the film plane. 

        PSSP's projector #2 is a TDC116 with SN 82644. It has a pair of 
        3mm thick, light green, infrared filters. The glass type is 
        unknown. The projector does not have a history of damaging film 
        or mounts, but has not been used for a number of years that we 
        know of. As the test data will show, each of the light green 
        infrared filters is equivalent to a pair of the light blue 
        infrared filters. 

        Bill Duggan's projector is a TDC716 with SN A02882. It has a 
        pair of 3mm thick, almost colorless, infrared filters. The glass 
        type is unknown. The surface is encrusted with white particles 
        that appear like table salt. The particles do not dissolve or 
        soften in water, alcohol, acetone, or vinegar. I have been told 
        that it is likely to be phosphates drawn from within the glass 
        over the years. The encrusted particles themselves present no 
        hazard. However, they scatter light so that some of it does not 
        pass through the film or the projection lens. The screen image 
        is much dimmer than it would otherwise be. No heat tests were 
        done using these filters. 

        Bill Duggan loaned me a Kodak Lamp Module of the type used in 
        Ektagraphic projectors. I tested the Kodak infrared filter in 
        the TDC projector just to see what can be expected using a 
        modern infrared filter. The infrared absorbing glass type is 
        unknown. I also tested the Brackett Dissolver at the last club 
        meeting.


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