Aperture
The usable optical area; check the clear aperture separately from outer dimensions.
TECHNICAL RESOURCES
A useful starting point
for optical selection.
Understand the key parameters before choosing or specifying a lens.
Focal length
A first selection parameter. Confirm measurement conditions and tolerance for your application.
Groove pitch
The spacing of the Fresnel grooves. It is one part of the optical specification.
Material
Public records list PMMA for the reference lenses. Confirm suitability for your environment.
Reference specifications
BHPA220-2-5 CSV ↓BHPA650-L CSV ↓Reference specifications. Enquire for current drawings and availability.
Frequently asked questions
Are these products currently available?
Enquire for current drawings, availability and lead time.
Can I request a custom size?
Share your dimensions and optical requirements to discuss a custom approach.
How do I send an enquiry?
Fill in the enquiry form and send it by email, or write to jssales@bhlens.com directly. Attach drawings to the email.
SELECTION & BUYER INFORMATION
Fresnel lens selection guide
How to choose a Fresnel lens
Start with the task: collecting light, forming a display, creating a line focus or magnifying an object. Then specify the illuminated area, source and receiver positions, wavelength range and mounting space. A model number and focal length alone do not define a complete optical system.
Circular or linear Fresnel lens?
A concentric Fresnel profile has optical power around its centre. A linear (cylindrical) Fresnel profile has power mainly in one direction and can form a line focus from suitably collimated light. The outline of the sheet does not identify its optical profile: a rectangular sheet can contain a concentric lens.
Outer dimensions are not clear aperture
Outer dimensions describe the part that must fit the holder. Clear aperture is the usable optical region. Supply both, including mounting margins and the position of the optical centre; do not assume that every millimetre of the sheet is optically usable.
Focal length is not a guaranteed working distance
Specify whether your source is collimated or at a finite distance, and where the receiver or display sits. Confirm how focal length is defined and measured, the wavelength and the permitted tolerance. A reference focal length is not a promise of the same source-to-lens or lens-to-screen distance in every setup.
What does groove pitch tell you?
Groove pitch describes spacing between adjacent Fresnel grooves. It is a geometric parameter, not a stand-alone measure of resolution, efficiency or spot size. Ask for a sample evaluation under your actual source and receiver conditions.
Is PMMA suitable for my application?
The two BHPA reference sheets list PMMA. Specify the wavelength range, operating temperature, outdoor exposure and cleaning conditions so material suitability can be reviewed. Do not infer transmission, UV lifetime or thermal limits from the material name alone.
General optical background: Edmund Optics — Fresnel lenses. This guidance helps define a specification; it is not measured performance data for a BHPA model.