Re: A PVA for printing "gum" from Mike Ware

----- Original Message -----
From: "Ryuji Suzuki" <rs@silvergrain.org>
To: <alt-photo-process-l@usask.ca>
Sent: Monday, April 03, 2006 2:14 AM
Subject: Re: A PVA for printing "gum" from Mike Ware

> From: martinm <martinm@gawab.com>
> Subject: Re: A PVA for printing "gum" from Mike Ware
> Date: Sun, 02 Apr 2006 13:53:26 +0200
>
> > The main goal is speed enhancement at 532nm. It may turn out that UV
> > pre-exposure will greatly increase speed for green light. No doubt,
speed
> > will remain weak compared to silver halides. But DCG has some features
> > silver halides cannot rival: notably bandwidth and index modulation. By
the
> > way, 532nm is the line where reasonably priced lasers fit for holography
> > (single frequency lasers) can be found relatively easily. So DCG
holography
> > becomes accessible to amateur holographers. Moreover, that green line
seems
> > to be important in the context of full color DCG. In addition, that
green
> > wavelength being highly visible, is very pleasant to work with.
>
> I don't really understand why you want to use 532nm for imagewise
> exposure. Laser may be cheap there, but then don't you have to expose
> and process in safelight?

The latter applies to all recording materials I've worked with (silver
halide, DCG, photopolymer).

There's yet another reason for the preference for 532nm light exposures:
when doing reflection holograms, DCG's main area of application, you might
expect a wavelength shift on the replay hologram. Unfortunately, most of the
time this shift takes place towards a shorter wavelength. So say, you'd
expose in the violet, you might easily end up in the UV region for the final
image.

Martin
Received on Mon Apr 3 04:17:35 2006