Achromatic Doublets & Objectives
Cemented achromats from single elements to instrument objectives — the color-corrected workhorse line behind our telescope platforms.
The Color Problem, Solved in Two Glasses
A single lens focuses blue short and red long; an achromatic doublet pairs a crown with a flint so two wavelengths share one focus and the visual band sits close behind. Our cemented doublets (and on-request air-spaced triplets) are built from BK7/SF pairings on the same grind-polish-coat line that produced 5,000+ lens types for instrument programs — including the objective cells inside Hemusun refractors.
Formats: mounted and unmounted doublets for OEM illumination, spectroscopy and imaging benches; cements held to practical field temperature limits; diameter up through telescope-class objectives with cell options in blackened aluminum.
Objectives, Not Just Elements
The line's real specialty is the objective: the two- or three-inch achromat is the soul of a beginner refractor, and the difference between an honest f-ratio doublet and a marketing number is exactly the kind of spec this factory measures. We supply finished objective cells — cemented, centered, AR coated, spaced in blackened cells — to our own instrument brands and to buyer brands building their own telescopes and monoculars on proven glass.
Verification is per drawing class: transmitted wavefront and focus checks on the bench, transmittance curves per coating campaign, and the same interferometer culture as the precision side of the house.
Frequently Asked Questions
Cemented or air-spaced?
Cemented doublets win on cost, centering robustness and ghost count; air-spaced triplets buy apochromatic-class correction. Tell us the residual color your sensor or eye tolerates.
Can you build our objective to a focal length?
Yes — send focal length, aperture, f-ratio and field; we return a prescription proposal with the glass pair and expected residual color stated, not a substitution list.
Do you sell the whole telescope too?
The component side supplies instruments to our own brands; instrument-level programs route to Hemusun Outdoor Optics (wholesale) or the brand division (OEM/ODM).
AR coating standard?
Single or broadband MgF-class AR is the baseline; multi-layer designs per band on request, with spectra shipped per campaign.
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Send a drawing — or a paragraph.
Coating design proposals, tolerance advice and tiered pricing, from the engineers who run the coater.