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αΩ-meter

personal light history

Version 1.00

The αΩ-meter records the personal spatial light history and allows for α-opic evaluation of arbitrary image regions.

Firmware

αΩ-meter:

The αΩ-meter is a camera based light dosimeter, that was developed as part of my PhD project. The αΩ-meter consist of a ESP32 microcontroller and an OmniVision OV2640 camera sensor with fish-eye lens. The dosimeter provides six channels. The five α-opic channels and a luminance channel:  sc, mc, lc, rh, mel and V(λ).

Parts:

  1. ESP32-CAM Board
  2. OV2640 with 160° lens (diagonal)
  3. 2x 1.5 V AAA lithium battery
  4. AAA battery clip
  5. 2x short wires
  6. Micro SD-card
  7. Housing (3D model available)
  8. USB-TTL adapter (firmware & calibration)
  9. Jumper wires female-female (firmware & calibration)

Flash the firmware:

To flash the firmware onto the ESP32-CAM board, follow these steps:

  1. Setup the flash toolchain ESP-IDF (eclipse recommended)
  2. Connect the USB-TTL adapter to the ESP32-CAM board
  3. Compile the firmware
  4. Flash the firmware

Assembly:

  1. Glue the battery clip into the case.
  2. Flash the firmware onto the ESP32-CAM board.
  3. Solder the two wires to the battery clip and the ESP32.CAM board, +3V and ground.
  4. Format SD-card with FAT32 format.
  5. Create the folders “calibration” and “data” on the SD card.
  6. Create settings file and add it to the “calibration” folder.
  7. Insert SD-card.
  8. Connect camera to ESP32CAM board.
  9. Insert 2x 1.5 AAA lithium batteries.
  10. Close the dosimeter case.

Calibration:

The calibration process is divided into several stages. For each step, Matlab and Octave scripts or prepared calibration files will be available after the PhD thesis publication.