Re: Magnesium Flouride

[Charles Bell <charbell@BELLSOUTH.NET>]

You can read quite a lot about various CCD chips used in astrophotography
at some the following links:
http://www.pk3.org/Astro/index.htm?astrophoto_ccd_comparison.htm

http://www.sony.co.jp/~semicon/english/90203.html
That was Sony.
Kodak also.

Every chip used in CCD or digital cameras has a spectral characteristic
curve that reveals its sensitivity across some spectrum of light.
400 to 700 nm is the range of wavelengths for visible light.

There is a web page for the ccd chip in one of the cameras I use to image
with is at:
http://www.quantumhyperspace.com/Astronomy/ICX098AK.html

The ICX098AK spectral response extends into the infrared and the camera, a
SAC7B, can be used to image the infrared.
The ICX098AK is a color camera and has three response curves whose peaks
correspond to the color in the electromagnetic spectrum.

Telescopes now come with UHTC coatings in the optics to improve light
transmission.

Maybe Magnesium Flouride  is the secret ingredient that Meade uses to
charge an extra $300 for the UHTC kind:
http://www.optcorp.com/cart/ProductList.asp?SearchBy=PK_KWID&SearchFor=84&SearchRestrict=PR_CATID&SearchRestrictID=1

Excerpt from add:
Ultra-High Transmission Coatings (UHTC) Group: Meade's Ultra-High
Transmission Coatings group permits an increase in total light transmission
to the telescope focus, averaged over the entire visible spectrum, of about
20%. LX200GPS-SMT telescopes equipped with the UHTC thereby yield
dramatically enhanced observable detail on the Moon, planets, and
deep-space objects.

At 06:04 PM 2/14/2004, you wrote:
> In high school optics we frequently do problems involving a thin film of
> Magnesium Flouride on a lens to enhance the tranmission in the middle of
> the visible spectrum because of a lack of sensitivity by the film (I
> hope I have this right).
>
> What about digital cameras?  Do their lenses need any form of such
> correction or are the photo arrays more uniformly sensitive across the
> visible spectrum?
>
> Thanks for any comments on this, I am an optical novice.
>
>     David Abineri
>
>
> --
> David Abineri
> dabineri@choice.net