Re: What's light integration ??? /UV exposure light boxes

From: Sandy King ^lt;>
Date: 02/04/04-09:02:56 AM Z
Message-id: <a06020406bc46b41f2490@[]>

A light integrator is a device that measures the actual amount of
light that falls on a given area, as detected by a photo sensor. You
could make an analogy to a water meter, that reads the actual amount
of water in gallons that flows to your house. So, with a light
integrator you make exposures in units of light, which once
calibrated, should always be the same, regardless of voltage
fluctuations, age of lamps, heat, warm-up time, etc.

Some enlarging timers, the Metrolux and Metrolux II for example, are
actually light integrators. There is a probe, or photo senor, that is
placed somewhere in the lamp housing and the unit is subsequently
calibrated to the light received by the sensor.

UV tube banks provide full output almost immediately on being powered
up but actual light output over an exposure of two or three minutes
can vary by as much as 10-20% depending on voltage fluctuation and
other factors. The light integrator makes it possible to repeat
exposures with an accuracy of 100%.

HID lamps are a different matter. They take quite a long time to
reach full output, ranging from 30 seconds or so with the lamps in a
NuArc 26-IK to a couple of minutes with commercial mercury vapor and
metal halide lamps. The only way to get consistent exposures with
these lights, without a light integrator, is to leave them on for the
duration of the printing sessions. This will cause a lot of local
heat and is wasteful of electricity.


>Ok, I'm stupid but what the heck is light intergration and these
>units you're talking about. Here I was just trying to decided
>between 24" bulbs or a metal halide (although this in itself is
>confusing me to no ends). All I want is a simple set up to put my
>contact frame under for 12 x 18 max size. Why won't just getting
>three or four two bulb holders with the BL bulbs in them, set 'em
>above the neg, plug 'em in and expose work?
> >From: Sandy King
> >Reply-To:
> >To:
> >Subject: Re: UV exposure light boxes
> >Date: Wed, 04 Feb 2004 00:57:14 -0500
> >
> >Any UV bank can be used with an integrator. Integrator hardware,
> >like most graphic equipment, is often available on ebay. Olec/Olix
> >is one of the common brands, but similar instruments made by Olec
> >are also sold by other names (Fuji, Tenac, etc).
> >
> >Sandy
> >
> >
> >
> >
> >
> >>Sandy,
> >>
> >>How hard is it to build a UV bank that incorporates an integrator?
> >>Is the hardware for the integrator readily available and/or
> >>expensive?
> >>
> >>Thanks,
> >>Mark Nelson
> >>
> >>
> >>In a message dated 2/3/04 12:11:00 PM, sanking@CLEMSON.EDU writes:
> >>
> >>>I would recommend a vacuum easel with either the
> >>>UV bank of MH light, though you might be able to
> >>>get away with a well adjusted printing frame with
> >>>the HID lamp because it functions more like a
> >>>point source. To counter this, you can get fairly
> >>>decent consistency in exposures with the UV bank
> >>>without a light integrator. With the platemaker
> >>>you will get both light integration and vacuum
> >>>easel built in.
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Received on Wed Feb 4 09:33:15 2004

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