Choose a CaF₂ crystal blank if you have in-house fabrication capabilities; choose a finished optic if you need a ready-to-install component. For an accurate custom CaF₂ RFQ, specify the material grade, dimensions, operating wavelength, surface quality, figure tolerance, coating requirements, quantity, and delivery schedule to help suppliers provide precise quotes.

Key Takeaways

• The blank-vs-finished-optic decision hinges on your in-house fabrication capability, required precision, schedule, and total cost of ownership — not just unit price.
• A finished CaF₂ optic shifts fabrication risk, surface quality responsibility, and final inspection to the supplier; a blank leaves downstream processing, inspection, and yield risk with the buyer.
• A complete CaF₂ RFQ should include a controlled drawing, material grade, operating wavelength, surface quality and figure, coating condition, acceptance criteria, test methods, traceability requirements, and quantity with delivery information.
• Every missing RFQ input either triggers a clarification email (adding delay) or forces the supplier to assume a specification and pad the quote (adding cost).
• CaF₂ is softer and more cleavage-sensitive than fused silica or sapphire, so edge treatment, mounting, and handling requirements should be specified explicitly in the RFQ.
• Some specifications — particularly tight surface figures on large diameters, custom crystal orientations, or specialized coatings — require feasibility review before a supplier can commit.

Should You Specify a Blank or a Finished Optic?

The answer depends on four factors: whether you have in-house grinding and polishing capability, the precision grade your design requires, your delivery schedule, and total cost of ownership including internal processing costs.

What is a blank? A CaF₂ blank is a crystal piece cut and possibly rough-ground to near-net shape, but without final optical surfaces, coatings, or finished tolerances. We supply blanks within diameters up to 300 mm and support custom crystal orientations.

What is a finished optic? A finished optic is delivered to your final drawing specifications — surface figure, surface quality, coatings, and edge treatment — ready for integration. We offer finished optics including plano-convex, plano-concave, bi-convex, bi-concave, and meniscus lenses; windows, waveplates, filters, mirrors, and beamsplitters; and prisms. We also deliver specialty shapes such as ultra-large lenses, crystal domes, cylindrical lenses, and custom-geometry pieces as finished optics.

How Does Delivery Scope Change Processing Responsibility, Inspection Standards, and Project Risk?

When you buy a finished optic, the supplier commits to achieving the specified surface quality, figure accuracy, and centering tolerances. As an example, our lens specifications are tiered by diameter: for 5–50 mm, surface quality of 10/5, figure accuracy of λ/10, and centration of 30″–120″; for 50–100 mm, 20/10 surface quality and λ/8 figure; for 100–300 mm, 40/20 and λ/4. Our flat optics follow a parallel structure: 5–50 mm at 10/5 surface quality, λ/10 figure, and 1″ parallelism; 50–100 mm at 20/10, λ/8, and 2″; 100–300 mm at 40/20, λ/4, and 5″.

When you buy a blank, you assume responsibility for all downstream processing and must have the equipment, process knowledge, and metrology to reach your final specification. CaF₂ is softer and more cleavage-sensitive than fused silica or sapphire, requiring protective edge design, careful fixturing, and controlled cleaning procedures. Residual stress from processing or mounting can introduce stress birefringence even though CaF₂ is intrinsically isotropic as a cubic crystal — so the buyer who processes a blank must control fixturing forces and thermal gradients during fabrication.

Acceptance criteria differ significantly between the two delivery forms. For a finished optic, you inspect the delivered part against your drawing at incoming. For a blank, you should require the supplier to report sub-surface damage, inclusions, striae, bubbles, and stress birefringence before you accept the blank for downstream work. Under the applicable Chinese group standard for UV-grade CaF₂ crystals, mandatory factory inspection items include appearance, scatter particles, striae, grain boundaries, transmittance, and stress birefringence.

What Information Belongs in a Custom CaF₂ Optic RFQ?

A custom optic RFQ should contain a controlled drawing or complete dimensional definition, critical optical performance and inspection requirements, quantity and delivery timing, application context, and quality documentation requirements. The drawing itself should define dimensions, tolerances, material, coatings, clear aperture, and applicable standards.

CaF₂-specific items that should appear on the RFQ or accompanying specification sheet include:

• Material grade: VUV, UV, laser, spectroscopic, or IR grade. Our crystal products are graded as LIF-A (single crystal, optical grade), LIF-B (single crystal, window grade), and LIF-C (polycrystalline) — reference the appropriate grade or equivalent specification.
• Surface quality: Commercial through precision optical.
• Surface figure / power: Interferometer-controlled, with the applicable tolerance stated for the relevant aperture size.
• Wedge / parallelism: Specified in arc-seconds or arc-minutes.
• Edge treatment: A protective chamfer is recommended for CaF₂ given its cleavage sensitivity.
• Coating condition: UV, VIS, NIR, MWIR, beamsplitter, or custom coating. For related CaF₂ coating materials, we also supply evaporation-grade granules.

The RFQ should state the operating wavelength or waveband, application type (laser, spectroscopy, imaging, infrared), and use environment (vacuum, cleanroom, laser power density) so the supplier can assess material grade and coating feasibility.

For finished optics, also specify clear aperture, edge exclusion zone, crystal orientation (if required), coating witness sample requirements, and whether test data must cover the actual delivered parts rather than a representative sample. For blanks, state whether polishing stock must be retained and require the supplier to report sub-surface damage, inclusions, striae, bubbles, and stress birefringence.

How Does Each Missing RFQ Input Affect Quote Comparability?

Every piece of missing information either requires an email clarification cycle (adding delay) or forces the supplier to assume a specification and build protective margin into the quote (adding cost), as noted by C\&W Engineering. When multiple suppliers each make different assumptions, the resulting quotes are not comparable. Below is an item-by-item breakdown.

Application and Operating Wavelength

State the wavelength or waveband and the application type. Under the applicable Chinese group standard for UV-grade CaF₂ crystals, the UV application band is defined as 190–400 nm; specifying "UV grade" without a target wavelength leaves ambiguity about whether VUV, excimer, or standard UV performance is needed.

Material Grade and Grade Evidence

Specify the grade (e.g., LIF-A, LIF-B, LIF-C, or an equivalent designation) and the purity or transmission requirements that define it. Without this, the supplier cannot determine crystal growth parameters.

Nominal Dimensions and Clear Aperture

Include all nominal dimensions and the effective clear aperture. CaF₂ specifications vary significantly by diameter range — our documented specification tiers show that surface quality, figure, and parallelism all relax as diameter increases — so an RFQ that omits diameter or specifies a figure tolerance without referencing the aperture size forces the supplier to clarify or assume the tightest (most expensive) tier.

Drawing Revision Number and Format

Provide the current revision number and file format. Quoting against an outdated revision wastes everyone's time.

Surface Figure and Surface Quality

Specify both values with reference to the aperture size. A λ/10 figure requirement on a 25 mm window is routine; the same requirement on a 250 mm window is a different class of work entirely.

Coating or Uncoated Condition

State the coating type, wavelength range, and performance requirements, or explicitly state "uncoated." Omitting this forces the supplier to quote both options or guess.

Test Methods and Environmental Conditions

Reference specific standard version numbers rather than generic statements like "per international standards." Ambiguous references create disputes at acceptance.

Acceptance Report Requirements

Under the applicable Chinese group standard for UV-grade CaF₂ crystals, mandatory inspection items are defined as: appearance, scatter particles, striae, grain boundaries, transmittance, and stress birefringence. Optional items — optical homogeneity and refractive index with dispersion coefficient — are tested only when the customer explicitly requires them. If your RFQ does not call out the optional items, they will not be tested.

Part Identification and Traceability

Specify marking requirements, lot traceability, and any serialization needs.

Quantity and Delivery Information

State the quantity, whether it is a prototype or production run, and the requested delivery window. For cylindrical lenses and other geometry-specific finished optics, incomplete drawings most frequently cause quote discrepancies at this stage.

Which Technical Requirements Need Supplier Feasibility Review?

Not every specification on an RFQ can be confirmed from a catalog or capability statement. Some require the supplier to review the specific drawing, assess crystal availability, and evaluate process feasibility before committing.

Categories that typically require feasibility review include:

1. Custom crystal orientations beyond standard cuts.
2. Surface figure or quality tighter than the supplier's documented standard tiers for the requested diameter.
3. Large-diameter or ultra-large optics approaching the upper end of the size range.
4. Specialized coatings or coating materials beyond standard offerings.
5. Extreme operating environments with high laser power density or temperature requirements.

Our CaF₂ crystals serve applications from deep-UV excimer laser systems (KrF at 248 nm, ArF at 193 nm, F₂ at 157 nm) through the infrared (working band 0.2–10.5 µm, transmittance 92%–94%), but specific performance at a given wavelength, thickness, and power density is project-dependent and requires review. We work with multiple fluoride crystal materials — CaF₂, MgF₂, BaF₂, LiF, SrF₂, and LiYF₄ — and material substitution or multi-material assemblies may be discussed during feasibility review when the application warrants it.

CaF₂ compared with fused silica: CaF₂ extends further into the infrared and has lower dispersion, while fused silica is harder, has a much lower thermal expansion coefficient, and is easier to fabricate. This means certain specifications that are routine for fused silica — tight figures on large apertures, aggressive edge geometries — may require feasibility review for CaF₂. Our manufacturing capabilities include ion-beam figuring (IBF) and cleanroom processing, which enable high-precision finishing, but whether a specific combination of figure, aperture, and material grade is achievable on a given schedule requires project-level assessment.

How Does a Complete RFQ Shorten the Clarification Cycle?

When we receive an RFQ, we assess material availability, crystal size and grade requirements, processing complexity, inspection scope, and delivery feasibility. A complete RFQ — one that includes all the checklist items above with specific standard references — allows us to return a firm quote without clarification cycles. An incomplete RFQ triggers back-and-forth emails, each adding delay.

Batch acceptance practices vary by supplier and region. Under the applicable Chinese group standard for UV-grade CaF₂ crystals, products are submitted in batches of the same process, with batches of 10 pieces (or fewer if the lot is smaller); type inspection under that standard uses a sample of 5 crystals from the same batch of raw material and process, and if one indicator fails, double sampling is performed — if any indicator still fails after double sampling, the entire batch is rejected. If your RFQ does not specify your acceptance sampling plan, the supplier defaults to its own, which may not match your quality system.

Specifying whether test data must cover the actual delivered parts or representative samples is a frequent source of post-delivery disputes that a well-written RFQ prevents. Transparency about which requirements are firm and which are negotiable helps both parties reach alignment faster.

FAQ

What is the difference between ordering a CaF₂ crystal blank and a finished custom optic?

A CaF₂ crystal blank is a piece cut and rough-shaped to near-net dimensions but without final optical surfaces, coatings, or finished tolerances. A finished custom optic is delivered to your drawing specifications — surface figure, surface quality, coatings, edge treatment — ready for system integration. When you buy a blank, you assume all downstream fabrication, metrology, and yield risk. We supply both blanks (up to 300 mm diameter) and finished optics including lenses, windows, prisms, and specialty shapes.

What information do I need to include in a CaF₂ custom optic RFQ?

A complete RFQ should include a controlled drawing with dimensions, tolerances, material grade, coatings, and clear aperture, along with operating wavelength, application context, surface quality and figure requirements, acceptance criteria, test methods, traceability requirements, and quantity with delivery timing. For CaF₂ specifically, state the material grade (VUV, UV, laser, spectroscopic, or IR) and specify edge treatment, since CaF₂ is cleavage-sensitive and benefits from protective chamfers.

How does choosing a blank versus a finished optic affect lead time and cost?

Choosing a blank typically lowers the supplier's unit price but shifts fabrication time, equipment costs, and yield risk to the buyer, so total cost of ownership may be higher than purchasing a finished optic — especially if you lack dedicated CaF₂ processing capability. CaF₂ is softer and more cleavage-sensitive than fused silica or sapphire, meaning in-house fabrication requires specialized fixturing, controlled cleaning, and careful handling that add to your internal costs. Confirm current lead times directly with the supplier, as they depend on crystal size, grade, and processing complexity.

Which CaF₂ material grade should I specify for UV, excimer, or IR applications?

The correct grade depends on your operating wavelength. Under the applicable Chinese group standard for UV-grade CaF₂ crystals, the UV application band is defined as 190–400 nm; excimer-laser applications at 193 nm or 157 nm fall within this range but typically demand higher-purity grades — confirm the appropriate grade with your supplier based on your specific power density and purity requirements. For infrared applications, CaF₂ covers a working band of 0.2–10.5 µm with transmittance of 92%–94%. Our crystal products are graded as LIF-A (single crystal, optical grade), LIF-B (single crystal, window grade), and LIF-C (polycrystalline); specify the grade that matches your wavelength and purity requirements, or describe your application so we can recommend one.

What acceptance criteria and test documentation should a CaF₂ optic RFQ require?

At minimum, your RFQ should call out the inspection items defined as mandatory under the applicable Chinese group standard for UV-grade CaF₂: appearance, scatter particles, striae, grain boundaries, transmittance, and stress birefringence. Optional items such as optical homogeneity and refractive index with dispersion coefficient are tested only when the customer explicitly requires them. Specify whether test data must cover the actual delivered parts or representative samples, and reference specific standard version numbers rather than generic compliance statements.

How do missing or incomplete drawing inputs affect CaF₂ quote comparability?

Every missing specification either triggers a clarification email — adding days to your quote cycle — or forces the supplier to assume a value and build protective margin into the price. When multiple suppliers each make different assumptions about an unspecified parameter, the resulting quotes are not comparable, making your evaluation unreliable. A complete, unambiguous RFQ is the single most effective way to get comparable quotes on the first cycle.

Who is responsible for downstream fabrication and inspection when buying a CaF₂ blank versus a finished optic?

When you buy a finished optic, the supplier is responsible for achieving the specified surface quality, figure accuracy, coatings, and edge treatment, and you inspect the delivered part against your drawing at incoming. When you buy a blank, you own all downstream processing and must have the equipment and metrology to reach your final specification. For blanks, your RFQ should require the supplier to report sub-surface damage, inclusions, striae, bubbles, and stress birefringence so you can assess the blank's suitability before committing your fabrication resources.

Next Steps

Your next step is to send us your controlled drawing or technical specification so we can assess feasibility and return a detailed quote. Contact us through desioptoe.com to discuss your requirements and start a custom quote.

Include all the checklist items discussed in this article — especially material grade, operating wavelength, surface and figure requirements, coating condition, and acceptance criteria — to enable a first-cycle quote without clarification delays.