Universal LightProbe™ Installation & Use - Check List
Universal LightProbes are fine instruments which should be treated with care.
Optomistic Products’ LightProbes are fully tested before shipment and are warranted against defect.
Optomistic Products’ warranty does not apply to damage caused by accident, misuse or abuse, or damage caused by modification of the product.
Please read through all instructions carefully before beginning installation.
1. Set and secure all fiber-optic probes and fixture components in their correct positions using Optomistic Products clamps or other custom designed fixture mounting techniques that wil ensure the fiber-optic probes are centered on the LED under test. Spring-tipped probes should be contacting the LEDs with a 1.5mm/0.060in. retraction. Do not remove protective tips on the “spring-tipped” probes, and do not glue or use adhesive to position the fiber-optic probes to the LED under test (Optomistic Products offers clamps for installation). Non-contacting fiber-optic probe tips should be spaced 1mm/0.032in. minimum from LEDs under test.
2. Set Universal LightProbe (ULP) Unicolor and Unicolor Digital fiber-optic probes in correct position. For example, a Universal LightProbe Unicolor Digital Red Sensor (ULP SCC/R) should be targeting the red LED.
3. Ensure Signal (“S”, “Int.”, “Color”), Power (“P”) and Ground (“G”) pins of all Universal LightProbe sensors are correctly connected to fixture ATE interface. No wire-ORed Signal leads to a common ATE driver-sensor as in the case of dual-well fixtures. Use separate D.C. power and ground wires for each sensor and single-point grounding to prevent ground loops and common-mode noise in signal measurements. Do not use solder on the sensors or sensor pins, as over-heating can cause damage to the sensors (Optomisitic Products offers optional color-coded connector cables. P/N: ULP-CC).
4. Connect Regulated D.C. Power Supply to all Universal LightProbe sensor “P” (+) and “G” (-) pins: +5 volts min., +40 volts maximum. Note that under +5 volts may cause the sensor readings to be unstable.
5. Ensure Probe Tip Apertures of all fiber-optic probes are clean and free of dirt and dust (it is best to use “Dust Off” cans of compressed clean air or equivalent, but not factory compressed air). DO NOT USE ISOPROPYL or RUBBING ALCOHOL on the probe tips as it can cause the glass in the fiber-optic probes to darken. DO NOT WIPE the probe tips with Q-tips as it may scratch them.
6. Ensure Ambient Light is excluded from all displays under test and from the fiber-optic probe tip apertures, both after the fixture is activated and during display tests.
7. For Clamshell Design - use bushings to align with tooling pins, to avoid the possibility of misalignment.
8. Accurate and Repeatable LED Intensity Measurement - Special Attention
a) Axial and Concentricity - ± 0.13mm (0.005in) of all fiber-optic probes and corresponding display device centers (per pcb HXY drill dwg./listing, pcb and DUT dimensional data) after vacuum/pcb push-down actuation. Double-check for consistency.
b) Contacting Fiber-optic Probe Tips retract 1.5mm (0.060in.) to 2.0mm (0.080in.) without sticking after vacuum/pcb push-down actuation and contact with corresponding display devices. Double check for consistency.
c) Fiber-optic Cables - Ensure bend radii is not less than 25mm (1.0 in.) for small aperture (“SA”) probes and 50mm (2.0 in) for wide-aperture (“WA”) probes to ensure free spring-tip action; 6mm (0.25 in) for super-flex (“SF”) fiber-optic cables. No visible cuts or kinks. No change in radii from one actuation to another, i.e., bend radii stable, except for super-flex (“SF”) cables, which are unaffected by changes in bend radius. Keep cables protected from crushing/ severe kinking during fixture handling and storage.
1. LED Forward Current - Set to a constant and stable value determined by a current limiting resistor on the circuit-board under test, or constant-current source per LED data sheet.
Warning Do not apply a voltage (VF) across the LED to turn it “ON,” since the resulting LED forward current (lF) and LED intensity will be indeterminate due to the steep slope and variations in LED lF versus VF characteristic curves. The result could be serious over-driving or under-driving of the LED.
2. Sensor Response Time - Sample the ULP sensor signal outputs (“S”, “Int”, “Color”) when they are stable, allowing up to 1.5 seconds after the LED is switched on, to accommodate dimmer LEDs and all sensor models, before reading the sensor output; the LED should remain on during this time period. Sampling too soon will provide erroneous and/or inconsistent readings.
3. Over-range - If the output voltage on the sensor “Int” pin is 50mV or less for any given LED under test, then the sensor is most likely “under-ranging” which can cause unstable “color” pin voltage readings. First check the distance between the fiber-optic probe and the LED under test (see #3) and check to be sure the fiber-optic probe is centered on/over the LED under test (#4). If both of these checks are satisfactory, the solution is to replace the sensor with a high-sensitivity (HS) model, available with our Universal LightProbe Penta (PCI/V) sensors.
4. Under-range - If for any given LED under test, the output voltage on the sensor “Int.” pins is 4 volts,then the sensor is most likely “over-ranging.” The solution is to either: increase the air-gap between the tip of the fiber-optic probe and the LED to 3mm (1/8th inch), or 6mm (1/4 inch) in order to reduce the output voltage to 3.0 volts; or to replace the sensor with a low-sensitivity (LS) model.