ILT detectors are designed to emit low levels of current in the pico-amp to milli-amp range which is then converted to calibrated optical units such as lux, W, W/cm2, etc., when used with ILT light meters. Detector assemblies typically include a sensor, filter, optic and calibration.
Example of a calibrated detector assembly for lux: "SED033/Y/W" includes the “SED033” 33mm² silicon photodiode detector, the “Y” photopic correction filter with the “W” Diffuser and calibration.
(Note: “/U” indicates an uncalibrated sensor).
The SED and SPM type optical detector housings are made of black anodized aluminum, with female filter threads (1¼-24), a tripod mount (¼-20), and two end mounts (#8-32). Only these housings allow for filter selection/swapping and underwater modification. All underwater modified detectors (SUD) require the W wide-eye diffuser in addition to any other filters and come special order in 10, 50 or 100 foot lengths.
The below four versions do not have removable, swappable filters and cannot be made waterproof:
The SCD type optical detectors are in a 42 x 19 x 14 mm housing.
The SSD type optical detectors are ultra-low profile (31 x 41 x 4.3 mm) detectors for UV measurements.
The XSD type optical detectors are in a 15 x 42 mm dia. housing with M6X1 tapped hole for mounting.
SPD type detectors are in a 121 x 19 mm dia. pen style housing.