NOTE: the wooden crate is not included in this listing. Only photographed to show brand.

This is one piece from a complete set of Schott colored-glass blocking filters that came from a original Boller & Chivens wooden shipping crate. The create was addressed to University of Arizona Purchasing & Stores, Steward Observatory, Tucson, with attention lines to observatory staff.

Specs

• Red RG, 630nm, Longpass Filter
• HARD MgF₂ anti-reflection coating (durable magnesium fluoride for maximum transmission and durability)
• Size: 215 mm × 215 mm square (≈ 8.5" × 8.5") — perfect for large-beam spectrographs

These were used as **order-sorting / blocking filters** in classic Boller & Chivens Cassegrain spectrographs at Steward Observatory (commonly on the 2.3 m / 90-inch telescope on Kitt Peak and similar instruments).

The RG 630 cuts off visible light below ~630 nm and passes red and near-IR, preventing overlapping spectral orders from the diffraction grating

Condition: Corner is chipped. See photos. Hard MgF₂ coating intact. No scratches. Still in original tissue wrapping from the foam-lined crate.

Great for restoring a vintage Boller & Chivens spectrograph, building a custom DIY spectrometer, optical fabrication (can be cut down), or display/collecting.

Keywords: Schott RG 630nm, MgF2, longpass filter, order sorting filter, astronomical filter, spectroscopy filter, Boller & Chivens, Steward Observatory, Kitt Peak, magnesium fluoride coated, AR coating

Shipping Information and Return Policy:

• Ships within 24 hours upon payment receipt.
• 30 day return warranty for US buyers only; the returned product must be in its original packaging, unused and undamaged. Shipping cost is non-refundable (both ways)

Contact us:

• Please contact us if you have any questions, comments or product requests. We will respond to you within 24 hours and do our best to help you out! We'd like to be sure you are completely satisfied with your purchase.