No signal, no problem
Reviews are written to your device first and synced when you come back up. A basement, a lead-lined room, a dead hotspot. None of it costs you a card.
Early access · SPI
The physics comes back right before you forget it.
Lucent is a spaced-repetition deck for the SPI exam. It shows you the cards you are about to lose and quietly skips the ones you already own, so ten minutes on a break is actually worth something.
Free while it is in early access. One email when it opens, nothing else.
- Free while it is in early access
- Reviewed by a working echo tech
- No card details
Physical Principles Try it: this is the real scheduler
A transducer is swapped for one that emits a shorter pulse. What happens to axial resolution?
Rate a card honestly and the next one is scheduled around it. Nothing to set up.
How it works
Three buttons and a bit of arithmetic.
There is no study plan to build and no schedule to keep to. You rate cards, and the scheduler does the part people are bad at: deciding when to see something again.
- 01
Rate the card honestly
Again if it was gone, Easy if it was instant. Four buttons, no scoring, no streak pressure to lie to. That is the entire input the scheduler needs.
- 02
The schedule moves itself
FSRS reads your ratings and puts each card back on the day you are about to lose it. Nothing to configure and no intervals to guess at.
- 03
Show up for ten minutes
Your queue is whatever is due, and an empty queue means you are done for the day. The streak counts days you turned up, not hours you sat there.
Why the timing is the trick
Cramming loses to a well-placed reminder.
Recall decays on a curve. Review too early and you spend attention on something you still have; review too late and you are relearning from scratch. The useful moment is the narrow band where the memory is just starting to slip.
Lucent aims every card at that band, roughly a nine-in-ten chance you still have it. Drag the slider and watch what a few well-timed reviews do to the shape of the curve.
91% chance you still have it, after 3 reviews. Reviewing now would be wasted effort. It is still solid.
What is in it
One deck, built to cover the SPI outline.
Organised by the content areas the exam is actually built from. Pick one to see where it stands.
in review
Physical Principles
Wave parameters, propagation, attenuation, the range equation: the arithmetic everything else leans on.
Every card carrying a number, a normal range, or a clinical claim is checked by a working cardiac echo tech before it ships. That is slower than generating a few thousand cards, and it is the reason to trust the ones you get.
Built around a shift
Made for the ten minutes you actually have.
Same account everywhere
Sign in on a desktop browser, pick it up on your phone, and the queue is where you left it. Progress lives with the account, not the device.
Readable at 5am
Warm paper instead of glare white, and a dark mode that is genuinely dark. Studying before a shift should not feel like being handed a flashlight.
Get in
Sign up once, study anywhere.
Signing up puts you in the first group let into the web app. One account covers every screen you open it on.
- On a computer Sign up, sign in, start reviewing in the browser. Nothing to download.
- On your phone Same site, same account, works in a mobile browser. The installable version (add to home screen, opens like an app, reviews with no signal) lands after that.
Free while it is in early access. One email when it opens, nothing else.
Questions
The things worth asking first.
No. Question banks hand you a pile of practice questions and leave the timing to you. Lucent is a spaced-repetition deck: it decides which cards you see today based on how you rated them last time, so the physics you keep missing comes back and the physics you own gets out of your way.