Domain: Engineering — Optical Engineering
Target concept: Laser Phase Matching

Video generation prompt: A laser beam is incident on a frequency doubling crystal (KDP). The frequency doubling device is activated, and the crystal angle is adjusted to achieve phase matching. A blue-transparent filter is placed on the exit side of the crystal. The outgoing light is observed, with the fundamental frequency light marked in red, the second-harmonic light marked in green, and the filter marked in blue transparent.

Evaluation guide:
(i) Target concept: Second-harmonic generation via birefringent phase matching in KDP crystal, enabled by angular tuning and verified by spectral filtering.
Minimum mechanism: Light must propagate through anisotropic nonlinear crystal; crystal orientation must affect internal wavevector matching; SHG power must depend on angle; filter must spectrally discriminate between ω and 2ω wavelengths; human-visible color coding must map ω→red, 2ω→green, filter→blue.
(ii)Storyline: Frame 1–2: Red laser beam strikes static KDP crystal → red light visible inside and exiting crystal. Frame 3–4: Crystal rotates smoothly → internal red intensity decreases, faint green begins inside crystal. Frame 5–6: Blue-transparent filter is placed adjacent to crystal exit face → red light reflected/scattered at filter surface, but no red transmission. Frame 7–8: Green light emerges *from crystal volume*, passes through blue filter, and propagates outward as sole visible output beam. Frame 9–10: Stable output: only green-marked beam visible beyond filter; no red pixels in output region; crystal retains adjusted angle; all color labels remain fixed to correct optical entities.

Manual:
Experimental Procedure
1. A laser beam (red-marked) is incident on a KDP frequency doubling crystal.
2. The crystal angle is adjusted until phase matching is achieved.
3. A blue-transparent filter is placed on the exit side of the crystal.
4. Output light is observed.
Observation of Experimental Phenomena
- Red-marked fundamental frequency light is visible before the filter and fully absent after it.
- Green-marked second-harmonic light emerges only after the filter.
- Blue-transparent filter is visibly adjacent to crystal exit face.
Summary of Experimental Principles
Phase matching in nonlinear crystals (e.g., KDP) enables efficient second-harmonic generation; angle tuning satisfies Δk = 0 condition; the filter selectively transmits SHG light while blocking fundamental frequency.

Prompt Grounding rubric:
level_1: None of the four required objects (laser beam, KDP crystal, blue-transparent filter, or color-coded outgoing light [red/green]) appear anywhere in the clip; no sequence resembling laser → crystal → filter → output is shown.
level_2: At most one of the four required objects (laser beam, KDP crystal, filter, or a colored output beam) appears, and no consistent red/green/blue color coding is used; any depicted action (angle adjustment, filter placement) is either missing or applied to the wrong object.
level_3: All four objects are present: an incident laser beam, a KDP crystal, a blue-transparent filter placed somewhere on the crystal's exit side, and an outgoing beam; red marking appears on the fundamental-frequency light and green marking on the second-harmonic light, and blue marking appears on the filter; however the spatial sequence may be inconsistent (e.g., filter not on the exit side, or a color used on the wrong beam).
level_4: All elements from score 3 are present AND correctly placed: the laser strikes the crystal's input face, the blue filter sits directly on the crystal's exit side, and the outgoing beam emerges past the filter; red marking is used only for the fundamental beam, green only for the second-harmonic beam, and blue only for the filter, with no beam left unmarked and no marking applied to the wrong object.
level_5: All elements from score 4 are present AND additionally: (a) exactly two labeled light components appear anywhere in the scene, one red (fundamental) and one green (second-harmonic), with no unlabeled or ambiguously colored beam segments; (b) the crystal's angular adjustment is shown via a visible rotation or an angle indicator, occurring before the filter is placed and before any green light appears; (c) the red/green/blue color coding stays attached to the correct object throughout, with no flicker, occlusion, or label swapping between frames.

Scientific and Causal Correctness rubric:
level_1: No frequency-doubling phenomenon is depicted: the crystal produces no second color, the output light stays the same color as the input beam, and the filter has no visible effect on which color(s) exit the setup.
level_2: A green-colored beam appears somewhere in the scene, but not visibly caused by the laser passing through the crystal and filter (e.g., it appears from an unrelated source); red light continues unchanged before and after the filter; the crystal shows no sign of being rotated or adjusted.
level_3: Green light appears in the output region only after the beam has passed the filter; red light is visible before the filter (as the incident beam or a reflection off the crystal) but is absent after the filter; the crystal appears as a static transparent block; the sequence laser → crystal → green output is visible, but there is no explicit visual cue tying the green light's appearance to the crystal's angle having been adjusted.
level_4: All elements from score 3 are present AND the crystal is shown being rotated, or its angle indicator changes, before any green light appears; green light appears only once both the angle adjustment and the filter placement have occurred; no red light (no red glow, tint, or scattered red pixels) remains visible anywhere in the beam path after the filter.
level_5: All elements from score 4 are present AND red light is visible inside the crystal volume itself before phase matching is reached, then visibly fades from within the crystal as the angle is adjusted; green light is shown originating from inside the crystal (not just appearing at its surface) and travels continuously through the filter into the output beam; at no point in the clip does any red light (including scatter or a faint halo) appear anywhere in the output region beyond the filter.

Spatiotemporal Consistency rubric:
level_1: The KDP crystal, filter, or beam vanishes and reappears at a different position between frames; the crystal or filter changes shape or breaks apart; light beams blink on and off with no continuous motion; the scene's lighting jumps abruptly with no transition tied to the depicted action.
level_2: The beam's position jumps discontinuously between frames; the filter slides sideways instead of staying fixed at the crystal's exit face; the crystal's outline stretches, shears, or rescales while supposedly just rotating; the red/green markings drift off their beams or flicker frame to frame.
level_3: The laser beam strikes a consistent point on the crystal's input face throughout; the crystal stays rigid and stationary except for its intended angular adjustment; the filter stays flat, fixed, and adjacent to the crystal's exit face; the red/green markings stay attached to their respective beams with no teleportation, warping, or unmotivated lighting changes.
level_4: All elements from score 3 are present AND the crystal's rotation is smooth and proceeds in one direction without back-and-forth jitter; the beam is visibly continuous from the crystal's entrance through its exit, through the filter, and into the output, with no frame where the beam appears severed mid-path; the red/green markings track their beams without slipping or lagging behind.
level_5: All elements from score 4 are present AND as the crystal's angle changes, the internal balance between red and green intensity shifts gradually and in step with the rotation (red visibly fading inside the crystal as green grows); the filter's blue tint and transparency stay visually constant across every frame with no fading in/out; the beam's blur (if any) stays consistent with the crystal's rotation speed rather than showing a frozen crystal next to a smeared beam.