The Baader Energy Rejection Filters (D-ERF): It allows H-alpha solar observation with the full-aperture resolving power of the telescope. It also dramatically reduce the thermal energy that passes through the telescope to the Solar Spectrum filter and also greatly reduces the thermally-induced seeing effects as well.
The filter-layers are designed with the utmost care. The coatings are applied with the world‘s most advanced optical coating machines, with the resultant final filters all being inspected and passed in an autocollimator on a Carl Zeiss optical bench in Germany.
To create the D-ERF filters, Baader use a 43-layer dielectric DWDM-coating which delivers a "cool"-beam of 45nm wide pure red light around the H-alpha wavelength, towards a solar H-alpha filter system. The filter glass substrate is clear BK7 glass that is of the highest homogeneity. It is fine-optically polished to the same degree of objective-lens surfaces.
The filter has all the reflection performance coatings on one side. This reflects all the unwanted wavelengths from 280 nm up to 1500 nm, but only leaving that 45nm-wide spectral window around the H-alpha wavelength. In addition, the Baader Planetarium D-ERF filter is coated in a way to keep the heat load on the glass as low as possible,
Features: Baader 90mm D-ERF Energy Rejection Filter With IR-Cut Dielectric Coating
- Lightweight, hard and scratch-resistant
- Plane-parallel circular disks having both sides optically polished
- Coated using ion-beam systems to keep the heat load on the glass as low as possible
- Features an infrared-reflective coating that prevents the penetration of heat into the telescope tube
- The blocking of IR (heat radiation) holds the D-ERF filter plane-parallel even with longer observation times
- Fine quality raw glass construction to cope with the stresses of solar use, while ensuring fantastic images and crystal clear observing
- Note: Never use any eyepiece filter for solar observation without objective front filter
Specifications: Baader 90mm D-ERF Energy Rejection Filter With IR-Cut Dielectric Coating
- Material: Raw Glass
- Filter Size: 90 mm
- Filter Shape: Round
- Filter Mounted: Unmounted
- Type Of Filter: Energy Rejection
- Single Or Set: Single Filter
- Visual or Imaging: Visual, Imaging
- Filter Usage: IR-Cut, Solar, Specialty, UV-Cut
- Ar-Coating: Dielectrically Coated, Planoptically Polished
Kit Contents:
Baader 90mm D-ERF Energy Rejection Filter With IR-Cut Dielectric Coating
Manufacturer's Warranty
Instruction / User Manual
For more information about, Baader 90mm D-ERF Energy Rejection IR-Cut Dielectric Coated Filter website.
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