KDP RG
Grade
RG = rapid-growth large-aperture KDP
Pick for metre-class ICF laser frequency-conversion and plasma-electrode Pockels-cell plates where aperture and lead time dominate over ultimate homogeneity.
Values for the RG condition
Other KDP tempers and conditions
KDP is listed in 3 conditions; see the grade overview at KDP.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
RGThis page Rapid-growth large-aperture KDP | Pick for metre-class ICF laser frequency-conversion and plasma-electrode Pockels-cell plates where aperture and lead time dominate over ultimate homogeneity. | — | 11 | 0 | 170 HV | 1 W/m·K |
Deuterated KD*P, ~70–98 % deuteration | Choose when low 1.06 µm absorption, larger electro-optic coefficient (lower half-wave voltage) or extended IR transmission to ~1.6 µm is required. | — | 11 | 0 | 165 HV | 1 W/m·K |
CONVDefault Conventional slow solution growth, laser/optical grade | Default choice for Pockels cells, SHG/THG plates and small-to-medium apertures where highest optical homogeneity and damage threshold matter. | — | 12 | 0 | 170 HV | 1 W/m·K |
What is KDP RG?
KDP RG is KDP in the RG grade — pick for metre-class ICF laser frequency-conversion and plasma-electrode Pockels-cell plates where aperture and lead time dominate over ultimate homogeneity. KDP RG has a tensile strength of 11 MPa (1.6 ksi), weaker than 92% of glass grades. Elongation at break is 0% and the elastic modulus is 43 GPa (6.24 Msi). KDP RG has a density of 2.34 g/cm³ (0.0845 lb/in³), lighter than 80% of glass grades. It melts at 253°C (487 °F). CONV is the default condition FabDigit quotes; RG is available on request or by drawing note.
Advantages
- Lightweight — 2.34 g/cm³ (0.0845 lb/in³), better than 80% of glass grades
Limitations
- Limited service temperature — 80°C (176 °F), worse than 100% of glass grades
- Low fracture toughness — 0.13 MPa·√m (0.118 ksi·√in), worse than 98% of glass grades
- Needs corrosion protection — 8/100, worse than 94% of glass grades
- Low stiffness — 43 GPa (6.24 Msi), worse than 83% of glass grades
KDP RG properties
Typical room-temperature values for KDP RG; 16 are specific to this condition. Other listed values are KDP reference data and may not represent this condition. Bars are the position among glass grades.
Physical5
KDP RG has a density of 2.34 g/cm³ (0.0845 lb/in³), lighter than 80% of glass grades. It melts at 253°C (487 °F).
Mechanical13
KDP RG has a tensile strength of 11 MPa (1.6 ksi), weaker than 92% of glass grades. Elongation at break is 0% and the elastic modulus is 43 GPa (6.24 Msi).
Thermal5
KDP RG is rated for continuous service to 80°C (176 °F). It conducts heat at 1.3 W/m·K (0.74 BTU/hr·ft·°F), worse than 54% of glass grades. Thermal expansion is 33 µm/m·K (18.3 µin/in·°F).
Electrical5
KDP RG is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 8×10⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (8/100), worse than 94% of glass grades.
Manufacturability2
KDP RG's machinability is poor (28/100, better than 66% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with KDP RG
Is KDP easy to machine?
Never use water — saw with wire/OD blade in oil or kerosene, then single-point diamond flycut; cleaves on {100}/{101}, so keep cuts light and stress-free.
Can KDP be welded?
Not weldable; elements are optically contacted, edge-bonded with low-stress adhesive, or mounted in oil-filled or dry-N2 hermetic cells.
Can KDP be formed, bent or molded?
Grown only from aqueous solution (temperature-lowering or rapid point-seed supersaturation) over weeks to months; no melt or ceramic forming route.
What surface finishes work on KDP?
Diamond flycut to λ/10 flatness and <2 nm rms, then sol-gel or low-temperature e-beam AR coating; store and use below ~40 % RH with desiccant.
KDP chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Kstoichiometric KH2PO4, M=136.09 g/mol | 28.6 – 28.8 | 28.73 |
| P | 22.6 – 22.9 | 22.76 |
| Hacidic protons; replaced by D in DKDP variant | 1.4 – 1.55 | 1.48 |
| metallic impurities (Fe, Cr, Al, Si)ppm-level control required for damage threshold | ≤ 0 | 5×10⁻⁴ |
| O | balance | — |
KDP RG — frequently asked
What is KDP RG used for?
KDP RG is typically used for laser frequency doubling/tripling, pockels cell electro-optic switches and high-power laser systems (e.g., ICF). In short: largest-aperture NLO crystal; water-soluble, oil machining only; 80 °C service ceiling.
What is the tensile strength of KDP RG?
KDP RG has a typical tensile strength of 11 MPa (1.6 ksi) — weaker than 92% of glass grades. Strength varies by condition: see the 3 listed tempers.
Is KDP RG easy to machine?
Not especially — machinability is rated poor (28/100, better than 66% of glass grades). Never use water — saw with wire/OD blade in oil or kerosene, then single-point diamond flycut; cleaves on {100}/{101}, so keep cuts light and stress-free.
Can KDP RG be welded?
Not weldable; elements are optically contacted, edge-bonded with low-stress adhesive, or mounted in oil-filled or dry-N2 hermetic cells.
What surface finishes work on KDP RG?
Diamond flycut to λ/10 flatness and <2 nm rms, then sol-gel or low-temperature e-beam AR coating; store and use below ~40 % RH with desiccant.
Can KDP RG be formed, bent or molded?
Grown only from aqueous solution (temperature-lowering or rapid point-seed supersaturation) over weeks to months; no melt or ceramic forming route.
What is the maximum service temperature of KDP RG?
KDP RG is rated for continuous use to about 80°C (176 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Properties of Optical and Laser-Related Materials — Wiley (Marvin J. Weber) (1997)
- Nonlinear Optical Crystals: A Complete Survey — Springer (D. N. Nikogosyan) (2005)
- KDP / DKDP nonlinear and electro-optic crystal datasheets — CASTECH / EKSMA Optics / Fuzhou crystal suppliers (2024)
- Landolt-Börnstein: Elastic, Piezoelectric and Dielectric Constants of Crystals (KDP group) — Springer (1993)
- KDP/DKDP KH2PO4 (2025)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.