AstroSolar® Safety Film OD 5.0 (ECO-size, 20x29)

The additional 10 cm outer diameter specified in our construction instructions refers to the cardboard filter cell described there and ensures that the finished filter holder has sufficient mechanical stability. It is not an optical or safety-related minimum requirement.

For a custom design, such as a 3D-printed filter holder, the surrounding ring can be made narrower, provided that the construction is sufficiently rigid and the AstroSolar film is securely held around its entire circumference.

It is essential that the AstroSolar film is mounted without mechanical tension. The film must not be stretched or pulled tight. A slightly loose or wavy appearance in the finished filter holder is perfectly normal and does not adversely affect its optical quality.

It is equally important that the complete filter holder is securely attached to the camera lens or telescope. The filter must cover the entire entrance aperture and must be secured in such a way that it cannot accidentally become detached during solar observation or photography, for example due to wind or accidental contact.

For attaching the AstroSolar film, we recommend the method described in our construction instructions using double-sided adhesive tape. Liquid adhesive should not be applied directly to the AstroSolar film.

What is meant, is that the film is optimized for high magnifications and has a fineoptical quality, that you are able to see/capture e.g. large sunspots etc., which is not possible with the film that is used in our Solar Viewers. However, Astrosolar of course also works excellent for lower magnifiaction devices such as the binoculars you mentioned. Feel free to use the film to manufacture your own solar filter.

We will have this size available soon

This inquiry is based on the assumption that the non-transmitted portion of a laser beam would be predominantly reflected. In general it is a valid question, but in this case not entirely accurate. AstroSolar® OD 5 is not a purely reflective system; a non-negligible fraction of the incident power is absorbed in the metal coating and converted into heat.

At 1550 nm in particular, the absorption characteristics differ from the visible range the material is optimized for. With a 10 W beam distributed over a 19 mm (1/e²) diameter, the resulting power density is sufficient to cause noticeable heating of the coating. Since the substrate is a very thin monomer-film with limited thermal conductivity, this can lead to local temperature increases, potentially resulting in deformation or damage of the film. Therefore, we would consider the use of AstroSolar OD5 in this application as thermally critical and not recommended for continuous exposure.

Regarding your concern about wavefront quality and tip/tilt:
A glass-based attenuator (e.g. wedged or dielectric design) provides significantly higher thermal stability. While it introduces a deterministic beam deviation depending on wedge angle and refractive index (typically in the mrad range), this effect is stable and can be compensated in the optical setup. In contrast, a film-based solution may introduce unpredictable distortions in the reflecting surface due to thermal effects.

For your application (≥OD4 attenuation at 1550 nm with minimal wavefront impact), we would recommend considering dielectric attenuators or beam sampling solutions specifically designed for this wavelength and power level.

The AstroSolar film may not be used on existing glasses and there is no adhesive element.
The eye safety norm EN ISO 12312-2:2015-11 for naked eye solar viewers does not apply to front aperture filters, covering long-range optics. AstroSolar® Safety Film 5.0 is not authorized to be used for naked eye solar observation or production of solar viewers. For direct solar viewing without telescope, binocular or camera optics, inquire for our EN ISO 12312-2:2015-11 certified eclipse shades equipped with AstroSolar® Silver/Gold Film.

We are in the process of producing the film again and it may still take a while. Please register your mail adress in the "please notify me.." field on the product page to be informed as soon as we offer the product again.