This instrument wants two panels and a keyboard side by side.
Please visit on a wider screen.

TONE//GRATING

A4 440 Hz β 2.405 CARRIER NULL

PATCH

SHARED

one number, both panels: where every note comes to rest

RESTING DEPTH β 2.405

TIME DOMAIN

STRIKE Δβ +0.0 STRIKE DECAY 0.30 s RATIO f_m/f_c 0.50 ATTACK 30 ms FADE WHILE HELD hold RELEASE 0.25 s

SPACE DOMAIN

GROOVE SPACING d 2.00 µm WAVELENGTH λ 500 nm

groove depth (p–v)191.4 nm

highest order±4

TIME sidebands at f_c + m·f_m drag the strip to press β

SPACE orders at sin θ = mλ/d or the grating itself

Z–M and Q–I play · Shift strikes harder · Space is the pedal · − / = octave · lower on a key is a harder hit

J_m(β)

computed once per frame for the note you last played, and drawn twice

m	J_m	J_m²	Hz	θ

Σ J_m²1.0000

folded below 0 Hz0

evanescent orders0

A hard strike is a deep grating: the spectrum crowds with sidebands and the fan of orders opens wide, then both close as the note settles. Land the resting depth on a zero of J₀ and the carrier drops out of the sound while the straight-through beam goes dark. The two axes still run out differently: a sideband pushed below zero folds back, and an order past sin θ = 1 stops propagating. Only the optical axis knows what color the light is.