Light & Optics Labλ = c / f • E = hf

661 nm to RGB & Color Calculator

Convert 661 nm monochromatic spectral light into exact digital sRGB, CIE 1931 tristimulus XYZ coordinates, THz frequency, and photon energy.

CIE 1931 Spectral Synthesis
661 nm
Red
#FF0046
nm
380 nm (Violet)555 nm (Peak)750 nm (Deep Red)
Frequency
453.544 THz
Photon Energy
1.876 eV
sRGB Channels
255, 0, 70
CIE 1931 XYZ
0.1504, 0.0616
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Why You See This Color (661 nm)

At 661 nm, photons interact exclusively with Long-wavelength sensitive (L) photoreceptor opsins in the fovea centralis. With a frequency of 453.544 THz and lower photon energy (1.876 eV), this stimulus yields the deep, saturated red sensation of monochromatic ruby and diode lasers. Near the 700–750 nm boundary, eye sensitivity tapers toward the infrared threshold.

Physical Parameter Breakdown

Wavelength (λ):661 nm (661 × 10⁻⁹ m)
Oscillation Frequency (f):453.544 THz
Photon Quantum Energy (E):1.876 eV
CIE 1931 Tristimulus (XYZ):X:0.1504 Y:0.0616 Z:0
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Traian Anghel
Traian AnghelAuthor & Reviewer

Physics Teacher & Educational TechnologistBrăila, Romania

Last Reviewed: August 2026
Wave Lab calculators are constructed using rigorous peer-reviewed physics formulas from verified metrological repositories. Every equation, spectral conversion, and acoustic property is tested against NIST, CIE, and ISO datasets.
Verified Sources:NIST CODATACIE 1931 2° ObserverNASA Glenn Research

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