Lunt LS40mm Hybrid Solar Telescope

Lunt Solar Systems has announced the LS40mm Hybrid Solar Telescope, a new addition to its solar product lineup. The telescope is expected to be revealed at NEAF 2025, with demonstrations and pre-orders available at the event. Pre-orders are not currently being accepted.

Details of the new Lunt LS40mm Hybrid Solar Telescope

The LS40mm Hybrid is a 40mm aperture f/10 Hydrogen-alpha solar telescope with a base bandpass of 0.6 Angstroms. It will be offered in three versions:

• Base Model: Features an internally mounted pressure-tuned etalon system.
• Pro Version: Includes an internal etalon system that achieves a bandpass of 0.45 Angstroms.
• Pro+ Version: A double-stacked model with an added front-mounted 40mm filter to reduce the bandpass to approximately 0.35 Angstroms.
   

LS40mm hybrid solar telescope specifications

The pressure-tuned system adjusts the refractive index of air within the etalon cavity to modify the central wavelength without physical contact. This method avoids mechanical stress and thermal interference, maintaining consistent performance across the etalon aperture.

Direct handling of an etalon with bare fingers can lead to significant changes in the transmitted wavefront across the etalon aperture due to small differential pressure and heat transfer from the fingers. These factors result in substantial increases in bandpass.

While an etalon's specification can be determined at any single point on its aperture, the true bandpass specification is dictated by the combined contributions of all points across the entire etalon surface. Historically, Lunt etalons have been specified at <0.65A, with a theoretical specification of 0.55A and a tolerance of +/-0.1A. Over time, Lunt has refined this tolerance to better than +/-0.05A.

Etalons subjected to physical compression typically exhibit a wider bandpass tolerance due to mechanical manufacturing inconsistencies. Lunt avoids physically compressing its etalons, thereby eliminating errors caused by mechanical deformation and thermal transfer, ensuring optimal performance of these precision optical components.

The center foot technique was previously used to adapt commercially available plates polished to 1/20th wave or better by bending them parallel. This approach often resulted in a slight bird-shaped residual tuning wavefront (TWF) across the aperture, with the lowest tuning points at the edges and center. Compression applied at the center and edges exaggerated this bird shape, increasing the central wavelength (CWL) variation across the aperture and reducing performance. For plates polished to 1/50th wave, the need for a center foot would be eliminated, ensuring superior optical precision.

The base price for the LS40mm hybrid is estimated at $899 USD

The base price for the LS40mm Hybrid is estimated at $899 USD. Final pricing may vary slightly due to adjustments in component costs and supplier pricing trends. The LS40mm Hybrid will be revealed at NEAF 2025.