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Table of Contents
Fisa-Yiil: 365nm Reflected UV Surveyor
The Fisa-Yiil is a full-spectrum digital observation unit. By removing the internal filters of a Raspberry Pi HQ Camera and replacing them with specialized UV-pass glass, we can observe “Nectar Guides” on flowers and skin damage invisible to the naked eye.
When paired with the DayHawk flashlight at night, this camera captures a world of “UV-Greyscale” where white flowers can appear black and clear water looks like ink.
In the Yivalese conlang, Fisa means "Bee" and Yiil means "Gaze" or "Sight."
Together, this unit provides a true vision of the birds and the bees in the ultraviolet realm.
The Camera Surgery: Removing the "Veil"
The Raspberry Pi HQ Camera (IMX477) comes with a small pane of blue-tinted glass sitting directly over the sensor. This is the IR-Cut Filter.
- The Surgery: There are two small silver screws holding the filter housing inside the C-mount ring.
- The Result: Once those screws and the glass pane are removed, the sensor is “Full Spectrum”–sensitive from 300nm (UV) to 1100nm (IR).
Danger: The sensor is now completely exposed. Any dust that enters will be permanent. Perform this in a “steam-cleaned” bathroom.
The Shiny Bits (BOM - Camera Edition)
| Item | Part Number | Description | Unit Cost (CAD) | Note |
|---|---|---|---|---|
| The Sensor | RPi HQ Camera | 12.3MP Sony IMX477 | $70 | Remove the 2-screw internal filter. |
| The UV Filter | ZWB2 (25.5mm) | UV-Pass / Visible-Block Glass | $18 | Crucial. Blocks all visible light. |
| The Glass | 25mm C-Mount | Quartz or “Simple” Glass Lens | $35 | Standard glass blocks UV; seek Quartz if possible. |
| The Brain | RPi Zero 2 W | Compact Processor | $22 | Small enough for handheld use. |
| The Display | 3.5“ DPI LCD | Real-time Viewfinder | $30 | Optional if using phone as viewer. |
Total Est. Cost per Unit: ~$175 CAD.
(~$145 if using a Phone as the Viewfinder - No LCD needed.)
(~$123 if you have a spare RPi Zero as well.)
Using a Phone as a Viewfinder
If you want to save $30 and skip the physical LCD, you can use the Pi Zero's built-in WiFi:
- Software: Use
mjpg-streamerorlibcamera-vidto host a local stream. - Connection: Set the Pi as a WiFi Access Point. Connect your Android/iPhone to the “Fisa-Yiil” network.
- Viewing: Open a browser (Safari/Chrome) or a dedicated “IP Cam” app to see the live UV feed.
Note: There is a slight (~200ms) lag, which makes precision focusing harder than a direct LCD.
Reflected UV: Why the Filter Matters
To see like a bee, your camera lens must have a ZWB2 (or UG1) filter attached to the front.
- The Illuminator (DayHawk): Hits the flower with 365nm UV.
- The Flower: Reflects some 365nm light and *fluoresces* (glows) some visible green light.
- The Camera Filter: Blocks the green “glow” and only lets the reflected 365nm reach the sensor.
The Map (System Integration)
[ SYSTEM ARCHITECTURE: THE FISA-YIIL ]
[ DAYHAWK (UV FLASH) ] ----> [ TARGET ]
|
| (Reflected UV + Visible Glow)
|
[ ZWB2 FILTER ] <-------------/
| (UV Only)
v
[ QUARTZ LENS ]
|
v
[ RPi HQ SENSOR ] (IR Glass Removed)
|
v
[ RPi ZERO 2W ] ----> [ WIFI ] ----> [ SMARTPHONE ]
(OR)
----> [ TFT LCD ]
Crow's Comments
- Daylight Usage: The DayHawk is primarily for indoor or nocturnal use. During the day, the sun provides high ambient UV levels, making an external flashlight unnecessary for most outdoor shots.
- The “Black Sun” Effect: Under the sun, the world looks like high-contrast noir due to unique atmospheric scattering of UV light.
- Focus Shifting: UV light focuses at a different point than visible light. Tweaking the focus slightly “shorter” than usual often helps.
- Lens Warning: Old “C-mount” lenses from the 80s are often better for this; modern multi-coatings are designed to block the exact UV light we want to capture.
Caw! Ready to see the secrets hidden in the petals?
