oh really....i think i must involve KEVIN here...to put more light here...
i was under impression THERMAL still wins the race....
and VIOLET are faster, but i am not aware of their quality....people here say violet is good for newspaper industry only.
put your more notions here meanwhile i involve kevin here.....
Thanks nshadab - it's kind of like being asked to comment on science vs. religion.
Luckily, it's not
quite as controversial as that.
A few
facts:
In the past, it was generally easier to make a visible-light (violet) system faster than a thermal system - mostly because the plates are photo-sensitive (like film), and required much less exposure / laser power to expose. However, over time the available power in laser diodes has gone up, the reliability of them is extremely high, and the cost has plummeted. Today, we can deliver thermal CTP's as fast as violet - over 300pph for newspaper applications, and >60pph for 8-page commercial CTP.
The speed diference is a thing of the past.
Violet CTP systems are almost exclusively "internal drum", using a single gaussian laser spot to expose the plates.
This fact is the main reason Thermal systems are higher quality than Violet systems. For Kodak, it goes one step further because of the our SQUAREspot thermal technology (only Kodak). The laser dot on a 2400-dpi gaussian device is actually about 1600dpi, so the dots overlap each other. Gaussian dots are always bright in the center, and fade towards the outside like a "bell curve". Those partially-exposed edges are what's sensitive to variation in the production process - sensitive to changes in exposure energy, plate sensitivity, preheat uniformity, processing conditions, and so forth. The narrower and sharper that edge, the less variation you'll see. SQUAREspot images with 10,000dpi dots (in a 4x4 grid to achieve a 2400dpi printing dot) - versus the 1600dpi gaussian dot. This makes
SQUAREspot 6x less sensitive to process variation. Yes, we have data to back that claim up.
That resolution and consistency is what allows you to push the boundaries of what you do. It can help you reduce costs for "normal" print work by making things much more consistent and reducing the need for careful oversight. Or, it can allow you to do much more challenging print work consistently.
Don't forget the advantages of daylight operation with many Thermal plates, as well as the fact that violet plates (including the "Chem-Free" type ones) need a preheat oven while most commercial thermal plates don't.
I can go on and on - but if you look at higher quality, larger, and more industrialized printers anywhere in the world, the vast majority of them are using and buying Thermal systems. Violet hardware is cheaper. But - you get what you pay for.
Kevin.
