LC3 User Manual

Light Counter is a precision light integrator system for ultraviolet printing processes. The system is designed by a photographer for photographers. It works simply and quickly, with a strong emphasis on ease of use.

LC3 Light Integrator

This guide is intended to help you to quickly start using your new LC3 Light Integrator.

Two Important Concepts: Measurement-based Exposures and ‘Units’

Measurement-based Exposures

Printing exposures are usually based on time, measured from the moment the lights are switched on to whenever they are switched off. Time-based exposures are easy to measure, but inaccurate because the intensity of all light sources varies over time, especially when the lights are warming up.

Light integrators allow photographers to make measurement-based exposures. These are based upon measurements of the actual intensity of light over the entire exposure. Measurement-based exposures are more accurate than time-based exposures, but require specialised equipment.

The Light Controller system uses a state of the art microprocessor, custom-designed digital sensor circuits and advanced software to bring measurement-based exposures within the reach of all photographers. The system was originally designed for platinum/palladium printing but will work for any ultraviolet-based printing process.

Measuring UV with ‘Units’

The light integrator measures UV intensity in micro-Watts per centimeter squared (µW/cm2), but this is pretty meaningless to most photographers. Calibration allows the light integrator to convert this raw measurement into things called ‘units’. These are much easier to use when printing.

After calibration, one ‘unit’ is about one second of exposure when the lights are at full power.

The light integrator does the necessary calculations and adjustments automatically, ensuring that your prints get the same exposure regardless of how the light intensity varies during exposure. You can even switch off your lights for a while during an exposure, and the light integrator will sort it out.

If the system has not yet been calibrated, then it will report the raw sensor measurement as units. For example, if the uncalibrated system measures 200 µW/cm2 then it will report this as 200 units.

‘Units’ are calibrated to a specific light source, so they are not comparable between exposure units. A 300 unit exposure under a low intensity light source is not the same as a 300 unit exposure under a high intensity light source. And because ‘units’ are an arbitrary measure, they are not comparable across systems made by different manufacturers.

System Devices

Light Counter is designed as a flexible system. The basic configuration has a light integrator and a single UV sensor. Advanced users can add additional peripheral devices to support their specific needs.

The system devices are:

  • The Light Integrator – “the brains” of the system. It controls the exposure, and all peripheral sensors and devices
  • UV Sensors – provide factory-calibrated measurement of the ultraviolet light source
  • Temperature Sensors – allow monitoring of the temperature inside the UV exposure unit
  • Power Controller – allows the light source to be automatically switched on and off by the light integrator

The Light Integrator

The light integrator is “the brains” of the system. It controls the exposure, and all peripheral sensors and devices.

During exposure, the light integrator continually measures UV intensity, and automatically adjusts the exposure time to allow for lamp warm-up and any fluctuations in the power supply.

LC3 Light Integrator

The LC3 (second generation) light integrator has a large 4.3” TFT display with a capacitive touch screen (using the same technology as your mobile phone or tablet computer). This allows incredibly easy set-up and control. It supports up to four sensors (UV or temperature), so you can monitor exposure in every part of your UV printing unit. It stores up to eight exposure presets, for fast switching between your favourite printing variations.

The LC2 (first generation) light integrator supports a single UV sensor and a single temperature sensor. It has a smaller display, and is controlled with buttons rather than a touch screen. The LC2 manual can be found here.

Both generations feature an automated calibration process, ensuring that your exposures are consistent even if you move the sensors.

Both generations support a power controller device that will switch your UV light source on and off as required. (The system works without the power controller, of course: you just have to switch the light source on and off yourself.)

UV Sensors

Two versions of the UV sensor are available. The standard version has a 365nm narrowband filter to optimise the sensor for iron-based printing processes. A broadband version without the filter is available by request.

Second Generation UV Sensor

The second generation UV sensors are factory-calibrated using a standard light source to ensure that all sensors have comparable readings. This is important because the inherent variability between sensors can be significant (sometimes as high as 25%).

Up to four UV sensors can be connected to the LC3 light integrator, allowing the entire printing area to be monitored during exposure.

First generation UV sensors designed for the LC2 light integrator continue to work with the LC3 light integrator, albeit without the advanced features introduced with the second generation sensor.

Temperature Sensors

The temperature sensor monitors the temperature inside your UV printing unit. This allows you to be confident that you are not over-heating your prints during exposure. Temperature sensors can also be used to verify that cooling systems are working effectively in all parts of the exposure unit.

First generation temperature sensors designed for the LC2 light integrator continue to work with the LC3 light integrator.

Power Controller

The power controller is an add-on device that allows the light integrator to switch the UV light source on and off. This brings extra convenience and a small increase in exposure accuracy.

Two versions of the power controller are available. The standard power controller can switch loads up to 5A, which is approximately 1100W in Europe, and 550W in the USA. This is sufficient for most photographers’ UV light sources.

Standard Power Controller

The professional power controller has double the capacity: 10A which is about 2200W in Europe and 1100W in the USA. This is designed for high intensity professional light sources, especially high power LED systems.

Connecting your LC3 Light Integrator

There are three types of connector on the back of the light integrator:

  • A standard barrel connector for the power supply
  • A 2.5mm stereo jack plug connector for the power controller
  • Four USB-A connectors for the sensors

Connecting the Sensors

Attach the sensors to the USB connectors on the light integrator using the supplied cables. It does not matter which USB connectors the sensors are attached to.

LC3 Light Integrator rear Connectors

During system start-up the light integrator will work out which sensors are attached and show this on the start-up display. This information can also be found by touching the Customer Support button.

The UV sensors should be placed near to the printing area pointing directly at the light source. It is important that they are fixed in a stable position: screwing them to the exposure unit wall is a good option.

The included USB cables are 1m long. The system has been tested with 2m and 5m USB cables, but whether longer cables work for you will depend on your environment. Long cables act like giant aerials, and electromagnetic interference can cause the sensors to work unpredictably. It is best to use the shortest cables possible.

Do not use multiple USB cables connected together. Do not use ‘active’ USB extension cables.

Attaching the Power Controller

The power controller is attached to the light integrator using a standard 2.5mm stereo jack plug cable.

The power controller has two mains electrical connectors, both standard ‘kettle’ type connectors (technically called ‘C13’ and C14’ connectors). The C13 connector (standard ‘kettle’) is used for the mains electricity supply. The C14 (‘kettle extension’) is used to connect the light source.

C13 (right) and C14 (left) Cables

The standard power controller is rated for a 5A load. The professional power controller is rated for a 10A load. Do not exceed these limits.

Connecting the Power

The supplied power adapter has connectors for North America, Europe, United Kingdom, Australia and China. Select the correct connector for your region. There is an on/off switch beside the light integrator power connector.

The first generation LC2 light integrator can be powered straight off a standard USB power adapter, but the big display used in the LC3 requires more current than USB can typically provide. If you wish to experiment with powering the system from USB, then please contact Ian Leake Studio. A suitable power cable is available on request.

Using the Light Integrator

After boot-up, the light integrator shows its ‘home‘ screen. From here you can access all light integrator functions.

Please note the colour of the touch buttons on the screens. Yellow buttons are activated immediately when they are touched. The darker orange buttons require a one second long touch to activate. This is a safety feature to protect from accidentally starting/stopping exposures or triggering other high impact functions.

The Home Screen

Exposure information is shown on the left:

  • The first line shows whether the device is set to measurement-based exposures (“UV Exposure Units”) or to time-based exposures (“Exposure Time”)
  • The second line shows the current exposure, which defaults to the most recent exposure used. This counts down to zero during an exposure. When making time-based exposures, this shows the remaining exposure time
  • The third line shows the UV intensity currently being measured (in units/second). This will show zero unless an exposure is ongoing
  • When making measurement-based exposures, the fourth line shows the duration of the current exposure. When making time-based exposures, this shows the total UV detected during the exposure (in units)
  • The bottom line shows the temperature measured by the temperature sensor (if attached)

There are four touch buttons on the right: Presets, Settings, Manual and Go!.

  • Presets – takes you to the screen for selecting and changing presets
  • Settings – takes you to the screen for configuring the light integrator
  • Manual – starts a manual exposure
  • GO! – starts an automatic exposure

Presets Screen

The presets screen has eight preset ‘slots’ – six for measurement-based exposures, and two for time-based exposures.

To select a preset, simply touch the ‘+’ symbol on the righthand side of the preset button.

To edit a preset, touch the lefthand part of the preset button. The button either shows the preset exposure value, or is blank if the preset has not yet been configured.

Settings Screen

The settings screen shows three configuration settings:

  • Temperature units – either centigrade or fahrenheit
  • Integration speed – either ‘standard’ or ‘fast’
  • Display brightness – either ‘brightest’, ‘bright’, ‘dim’ or ‘dimmest’

Touch the appropriate button to cycle through the setting values.

When set to ‘standard’ integration time, the light integrator takes a single highly accurate reading every second. When set to ‘fast’ integration time, the light integrator sacrifices a bit of precision in order to take six quick measurements every second. The former is most suitable for long exposure times, and the latter is most suitable for short exposures.

There are four buttons on the right of the settings page:

  • Calibrate – which starts the calibration process
  • Reset – which triggers a factory reset
  • Customer Support – which shows a page of troubleshooting information
  • Home – which returns the light integrator to its home screen


Calibration does two things:

  1. It converts the raw UV measurements into ‘units’
  2. It helps to eliminate measurement errors due to placement of the sensors

The second point is important. All light sensors are highly sensitive to the distance from the light source they are measuring, plus their orientation to the light source. Turning a sensor by just 10 to 15 degrees can have a significant effect on its measurements. Calibration helps to eliminate this.

First fix the sensor in your preferred position (see above).

From the home page touch Settings, Calibrate then Calibrate again. The third button requires a one second long touch.

Calibration has two stages:

  1. Waiting for all attached sensors to report stable UV light intensity. This stage can last several minutes depending on your light source. During this stage, sensors that have stabilised are marked with a green dot, and sensors that have not yet stabilised are marked with a red dot. Once all sensors have stabilised the calibration process moves to the next stage
  2. The second stage lasts for one minute, during which the light integrator continually measures the UV light. At the end of this phase it calculates a suitable conversion from raw sensor readings into units. The light integrator beeps once calibration is completed, and returns to the home page
Calibration – Waiting for the Light Source to Stabilise
Calibration – Measuring the Light Source

If you interrupt the calibration process using the ‘Stop’ button then the calibration process will be halted.

Automatic Exposure (GO!)

To start an automatic exposure:

  1. Choose a suitable exposure preset, either measurement-based or time-based
  2. Touch the GO! button from the home screen (a one second long touch)

If a power controller is attached, the light integrator switches on the UV light source, and immediately starts measuring UV light. Once the exposure is complete, it switches off the power controller and beeps to indicate reaching the end of the exposure. If you do not have a power controller attached, then switch off the lights manually when the light integrator beeps.

If you have set a time-based exposure, then the exposure time starts from the moment UV light is first detected.

Manual Exposure

To start a manual exposure, touch the Manual button on the home screen (a one second long touch). Manual exposures ignore the preset you have selected. The power controller is switched on if attached, but is only switched off when the stop button is touched (one second long touch).

During a manual exposure, the raw values measured by each sensor are displayed, and also the units of exposure. This can be useful for troubleshooting your exposure unit.

Migrating from an LC2 Light Integrator

The main differences between the LC2 (first generation) and LC3 (second generation) light integrators are:

  • Changing to a large touch-screen display
  • Support for multiple sensors
  • Support for exposure presets
  • Improved calibration process for greater precision
  • A host of usability enhancements

The LC2 (first generation) and LC3 (second generation) light integrators use the same definition for ‘units’ so their exposures will be broadly comparable (assuming both systems are calibrated using the same exposure unit). Many people will see no difference between the two.

However, given the improved calibration process and more precise sensors, so it is possible that there may be a slight difference between your new LC3 exposures and your old LC2 exposures. It is recommended to make some test prints to verify your exposures before making critical prints.

It is not strictly necessary to place the new LC3 sensors in the same place as the old LC2 sensor, although doing this will make troubleshooting easier.

Product Safety Notices

  1. Electrical safety. Light Counter devices use low voltage power supplies, and are in general very safe to use. However two components use mains electricity and require normal common-sense precautions. These are the power adapter (only use the supplied adapter) and the power controller device (this switches the mains supply to your light source, so do not open the device with mains cables attached)
  2. More electrical safety. The standard power controller is rated for a 5A load. The professional power controller is rated for a 10A load. Both may work with higher loads, but prolonged usage may damage the device or in worst be a fire risk. If in doubt consult a qualified electrician
  3. If any device gets wet, immediately switch off the power supply. Allow the device to dry out before reconnecting
  4. Devices contain static-sensitive components. Opening them will void the warranty
  5. Only attach cables when the power supply is disconnected
  6. Do not connect the sensors or light integrator USB connectors to a computer. The system uses USB cables for convenience and low cost, but does not use the USB protocol. Connecting a computer to these devices may damage the computer and the device

Neither Ian Leake nor Ian Leake Studio accepts any liability to any person or entity with respect to loss or damage caused or alleged to have been caused directly or indirectly by use or misuse of this system.

Customer Support

If you need any assistance then please contact Ian Leake using the email address at the bottom of this page. It would be helpful to attach a photo of the Customer Support screen with your email.