Lightmeter / 4meter

An easy-to-use instrument to accurately determine the intensity of phototherapy treatment.


The 4meter is used for the determination of the actual level of sources required for effective medical therapy. The tool is useful for both hospital technicians and doctors who want to verify whether the medical equipment can deliver all the functions as designed.
The primary light meter function provides precise measurement of the intensity of the blue light spectrum that is necessary to treat jaundice in infants. This measurement allows health professionals to ensure phototherapy units are working correctly and determine when a phototherapy device or its bulbs need to be replaced.
The device can be used for any phototherapy unit with LEDs, fluorescent bulbs or compact bulbs. When measuring a single-sided phototherapy machine, it will measure the light using the front sensor. When measuring a double-sided phototherapy, the device reads the intensity from both sides, using the sensors on the front and back of the device. It then displays the sum of the values from each side.



By measuring the wavelength spectrum from 400 to 520 nanometers, the light sensor gives a reliable irradiance measurement and helps to comply with the American Academy of Pediatrics Guidelines.


The light sensor provides a quick and accurate measurement of therapeutic light intensity from any kind of phototherapy device to make sure that the patient is receiving the most effective amount of light.


The device can also be used as a tool for clinical decision making, allowing the care giver to determine how to position the baby, maximize light exposure, and provide the strongest phototherapy.

Key Features

Key Functions
1. Blue light irradiance measurement:
– verify irradiance of photo therapy devices during preventive maintenance and normal use
2. O2 measurement:
– verify purity of O2 sources (tank, generator, wall) during preventive maintenance
– verify mechanical blender and other blender during preventive maintenance
– leak search inside device and along external tubes during repair and equipment inspection
3. Pressure measurement:
– verify pressure at Y connector during use
4. Flow measurement:
– verify flow output of CPAP, Hi-flow and ventilators during preventive maintenance
5. High pressure measurement:
– verify hospital gas sources and check them for uctuations
6. Temperature and humidity measurement:
– verify the temperature uniformity of the radiant warmers
– check temperature and humidity inside the incubators

Light Irradiance Sensor
– spectral response chosen to match wavelength used for Jaundice treatment
– two sided measurement for convenient measurement of double-sided phototherapy devices such as MTTS Firefly.

– touch screen liquid-crystal display (LCD)
– low battery
– 5 second result display time
– system failure
– out of measurement

– long battery life.
– standard AAA alkaline batteries are easy to replace


Easy To Use

The 4meter features a large, clear display that makes it easy to read under all lighting conditions.



The 4meter is lightweight and portable. It can be carried around easily and helps health professionals to feel confident in the therapy they provide to their patients.



The 4meter can be used to measure the intensity of any type of phototherapy as well as the true level of flow, pressure and oxygen level of the gas sources.

Technical Specifications

Dimensions and WeightHeight148mm
Performance Specifications
LIGHT SENSORApplicationLED and blue fluorescent phototherapy light sources.
Spectral Response400-520nm
Measurement Rangesingle0.1 – 150.0 μW/cm²/nm
double0.1 – 300.0 μW/cm²/nm
Resolution0.1 μW/cm²/nm
Cosine characteristics±2% @ 30 degree angle
±7% @ 60 degree angle
±25% @ 80 degree angle
Accuracy+/- 3% of reading
PRESSURE SENSORPressure0-100 cm H2O
FLOW SENSORFlow0-160 lpm, bi-directional
Humidity0-100% RH
Battery SpecificationsType2xAA 1.5V Alkaline, Non-rechargeable
LifetimeUp to 120h operating time.
Maximum usage time when fully
4 hours
Display SpecificationsTypeTouch screen
Environmental SpecificationsOperating Temperature10°C to 40°C
Storage Temperature0°C to 50°C
Operation Humidity30 – 90% RH non condensing
Storage Humidity5 – 90% RH non condensing
Operation Atmospheric Pressure70 – 106 kPA
Storage Atmospheric Pressure70 – 106 kPA
Calibration ScheduleEvery 2 years, measured from delivery date.
Return to MTTS for calibration.
ServicingNo customer serviceable parts.

Standard warranty 1 year.

(Subject to MTTS policy)

Ordering Information and Servicing

Ordering InformationLightmeterLM-800Main Unit
Oxygen meterLM-800-020Optional
Flow meterLM-800-030Optional
High pressure meterLM-800-050Optional
Temperature/Humidity meterLM-800-060Optional
Rechargeable batteries
and charger
Storage caseLM-800-080Optional