Recommendations on Lighting Conditions for Erasing Imaging Plates
In order to completely erase imaging plates, 99.5% of the image information must be removed. Scanning only removes part of the information. To completely erase imaging plates, follow the guidelines given below. It is important that you measure the light intensity with a light meter at the point where the imaging plate will be positioned. The intensity of light changes dramatically as you move away from the source. Erasing the imaging plates for periods of time longer than suggested does not harm them. A good place to store your imaging plates is under the erasing light source.
œFluorescent Lights
A light box typically gives off between 1000 and 5000 lux. Measure your light box and use the lowest value to determine the erasing time. At 1000 lux, an imaging plate will be erased in 1 minute. At 2000 lux or more, 30 seconds is sufficient.
œIncandescent Lighting
At 1000 lux, an imaging plate will be erased in about 2 minutes. At 2000 lux or more, erase for 1 minute.
œSunlight
Full sunlight on a bright day can be as strong as 70,000 lux. At this intensity, it takes less than 10 seconds to erase imaging plates. However, sunlight is too variable, and we do not recommend using it.
If you are unable to directly measure the light output from your erasing light source, or do not have an erasing light source greater than 1000 lux, use the practical test, below, to determine your erasing time.
Practical Test
1.Completely erase an imaging plate by subjecting it to direct, intense light for about 20 minutes.
2.Scan the imaging plate. No image should appear on the monitor. If an image does appear, repeat step 1 with a more intense light source.
3.Place the imaging plate in a sleeve or cassette.
4.Expose the imaging plate using normal exposure conditions. If possible, place an object, in the path of the
5.Turn on your erasing light source. We recommend a light box or a minimum l00- watt incandescent light bulb (see Section 5.2).
6.Remove the imaging plate from its sleeve or cassette and place it with the blue side toward the light for 2 minutes.
7.Scan the imaging plate. If an image appears, the plate was not completely erased. Repeat step 6, adding a minute to the exposure time. Continue to repeat until no image appears on the monitor. Record the erasing time that resulted in no image. This is the time required to erase an unscanned imaging plate.
8.Repeat steps
9.Remove the scanned imaging plate and place it, in the dark, into a
10.Now repeat steps 6 and 7, exposing one plate (blue side toward light) to the erasing light for 2 minutes, the next plate for 3 minutes, etc., until you find the point where no image appears on the monitor. This is the time required to erase a scanned imaging plate.
The time required to erase an imaging plate will vary depending on the quality and intensity of the erasing light source. It should be fairly easy to find a light source that will erase imaging plates in
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