Pangolin PASS User manual

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PASS
Professional Audience Safety System
User Manual for PASS version 1.5 March 2015
Important Information
PLEASE READ THIS ENTIRE MANUAL VERY CAREFULLY, INCLUDING THE LICENSE AGREEMENT AND
LIMITED WARRANTY FOUND IN THE BACK OF THIS MANUAL. FAILURE TO FOLLOW THESE INSTRUCTIONS
VERY CAREFULLY COULD LEAD TO AN INCREASED RISK OF AN UNSAFE LASER EXPOSURE.
This manual contains important information on how to install PASS in a laser projector, how to perform
adjustments, and how to make sure that the show remains safe – including a requirement to test your
laser projectors before each show and log the test results.
Introduction
Congratulations on selecting Pangolin’s Professional Audience Safety System, an important step toward
helping to keep your audiences safe from the potential hazards that laser projection systems may pose.
You have purchased a powerful and patented laser projector safety monitoring system for laser light
show usage.

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This manual serves as a brief introduction to PASS, so you can install it and get started.
Pangolin provides you with the PASS hardware board, connection cables, and this manual.
You must provide a laser projector including laser, scanners, shutter and power supply.
You must also use a light sensor to ensure maximum protection. An optional control panel may also be
used for maximum flexibility.
PASS is a sophisticated system which, when properly integrated into a laser projector and used with the
proper show presentation techniques and Pangolin software, can assist in maintaining the safety of
Audience Scanning laser shows.
PASS is barely bigger than a credit card, and yet it includes a set of very sophisticated and complete
protection systems.
PASS hardware is designed with multiple levels of redundancy and with circuitry that is designed to fail-
safe. In fact PASS is designed to maintain safety even in the face of several simultaneous failures.
Although the PASS hardware circuit board itself is designed with redundant circuitry, some of the
redundancy of the entire system is provided by external elements, such as the shutter, light sensor, and
projector interlock. This is why these additional items are very important, and mandatory for most uses
of PASS.
This manual discusses how to install, connect, and adjust PASS. You must read and fully understand this
manual before installing and using PASS. Pangolin also conducts private training sessions that integrators
must attend, before Pangolin will sell the PASS hardware.
NOTICE! Pangolin will only guarantee the proper operation of PASS when it is used in conjunction with
Pangolin software and control hardware (i.e. QM2000, FB3 or FB4). In addition, Pangolin strongly
recommends the use of only ScannerMAX series of scanners and servo drivers, or alternatively
Cambridge model 6210 or 6215 scanners with associated servo drivers made by Cambridge Technology.

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Brief Theory of Operation
Ideally the PASS circuit is installed inside the projector, rather than externally. PASS may be inserted into
the ILDA (analog signal) signal stream, or alternatively inserted into the signal stream after your own
projector electronics (such as differential color receivers or scanner invert switches) but before the
scanner servo drivers and laser modulators or drivers. Given this location within the signal path, PASS is
able to interrupt the flow of the color signals, as well as forcibly close the shutter and open the projector
Interlock circuit if necessary.
PASS monitors the following projector-health-related properties:
Scanner power supply and internal PASS power supplies
Scanner position signals to derive:
Scanning velocity
Effect size
Horizon( “Protected Area”)
PASS logic system
Beam Power during both blanked and non-blanked periods
Control Panel signals, including ESTOP and Manual Reset (optional)
Power Supply monitor and critical fault response
When power is not applied to PASS, or when PASS detects that the power supply is not sufficient to
properly operate the laser projector, PASS will crowbar (short-circuit) the color signal inputs, and forcibly
close the shutter and intensity outputs. PASS will also open the projector interlock signal path (ILDA pins
4 and 17). As long as a fast shutter is located within the beam path and as long as the interlock signal
path is used within the projector, this dual action will prevent light from being emitted from the projector
under all circumstances.
Since the shutter is closed and projector interlock are opened during critical fault conditions, these two
external elements are able to work in a redundant fashion, incase either of these were to fail individually.
Because of this, PASS requires the use of both the shutter, and projector interlock.
Scanner Position Signal monitoring
PASS monitors the X and Y position signals and derives Euclidian vector velocity as well as effect size. If
the vector velocity is found to be below the Minimum Velocity (the minimum speed that the beam is
required to sweep, in X and/or Y, in order to be considered to be safe), and found to remain there for a
period longer than the Dwell Time (the time that a beam may remain at or below the minimum velocity
see page), PASS will blank (pull to zero volts) all color signals and the intensity signal. PASS will only do
this for the period of time that the beam is below the “Minimum Velocity”. As soon as the beam speeds
back up, or the beam enters a non-protected area (i.e. above the horizon if enabled), PASS will allow the
color signals to flow from the Input to the Output. The Effect Size has a similar result, and this is included

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in PASS as a measure of redundancy. If there is an effect that is scanning very quickly, and which would
satisfy the “Minimum Velocity”, but if this is a very small effect, PASS will blank the color and intensity
signals until the Effect Size resumes a safe level. The Effect Size is not adjustable on this version of PASS.
Note that during momentary interruptions of color and blanking signals, PASS does not affect the Shutter
output.
Control Panel Signals
A control panel may optionally be used with PASS. The control panel may have a ESTOP switch (i.e.
mushroom emergency stop switch), as well as a manual reset button, which may be embodied as a
keyswitch or push button. When a control panel is used with PASS, a Manual Reset is required in order to
activate PASS, and thus, start projector operation. In most cases, this is a simple keyswitch action but
could also be a simple momentary push button. And when a Control Panel is used, PASS continually
monitors the ESTOP button. If the ESTOP is pressed, PASS will immediately terminate all color and
intensity signals, and forcibly close the shutter. PASS will also open the projector interlock signal path
(ILDA pins 4 and 17).
Beam Power Monitor
The Beam Power Monitor is perhaps the most unique and important aspect of PASS. The Beam Power
Monitor is able to make sure that the light coming out of the projector conforms to what is expected.
When PASS commands that no light should be emitted from the projector, PASS will verify that this is so,
by observing the Beam Power Monitor. If light is coming out of the projector when it is not supposed to
be, PASS will forcibly blank the color and intensity signals, close the shutter, and open the projector
interlock signal path. PASS does this because this would be considered a critical problem. Likewise, if
PASS detects that light is commanded from the computer, but is not coming out of the projector, PASS
will take this same kind of critical action, because this could be a sign that the light sensor is not working.
And finally, PASS will measure the Beam Power against a “Maximum Safe Beam Power” adjustment, and
if it is exceeded, PASS will take the same critical action, forcibly blanking the color and intensity signals,
closing the shutter, and opening the projector interlock. Any of these conditions requires the power to be
recycled, or a Manual Reset. Under normal circumstances, this will never occur. There should always be
congruence between commanded power and actual light coming from the projector. And light coming out
of the projector above the “Maximum Safe Beam Power” level is, of course, also a sign of trouble. See the
section on “Using PASS with a light sensor” below for additional information.

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PASS Logic System monitor
The PASS circuitry is implemented almost entirely in analog circuitry. There are logic circuits within PASS,
but these logic circuits are entirely combinatorial in nature. This means that the logic is made up of
simple AND and OR statements, which can be easily understood by peers in the safety community. There
are no sequential-logic circuits within PASS, nor are there any microprocessors, which could not be fully
validated.
In addition to the logic used by PASS to implement the basic safety features, PASS also includes a
separate layer or logic that actually watches the first logic layer, and verifies sanity. If there is a problem
within the PASS logic, the color and intensity signals are blanked, the shutter is closed, and the projector
interlock signal path is opened. The system will remain in that state until power is recycled, or until a
Manual Reset is performed.
Layout and Connections
The general layout of PASS is shown above, with connectors identified.
Pangolin includes connectorized ribbon cables with PASS. These ribbon cables can be used directly,
allowing minimal effort to integrate PASS within a projector. When ribbon cables have a red stripe on one
side, the red stripe indicates the side of the cable associated with pin 1.
J801: Projector-Signal-Input
The Projector-Signal-Input to PASS may come directly from the DB- 25 input on the projector, or may
come after projector internal electronics that condition the color signals (for example, allow adjustment
of intensity for each color or scanner axis inversion and rotation). When PASS is used for direct projector

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input, a simple crimp-on DB-25 connector may be used, and crimped onto the Projector-Signal-Input
ribbon cable provided with PASS.
J802: Projector-Signal-Output
The Projector-Signal-Output connector on the PASS board should be parsed out into pairs of signals, and
then directed to various components within the projector. The signals and recommended connections are
discussed below. Note that since this is an IDC connector, the pin numbers do not correspond to the ILDA
pin-out on a DB-25. HOWEVER, if you crimp a DB-25-connector onto the output ribbon cable, then the
pins will correspond directly to the ILDA pin-out. This is because the pin designations of a DB-connector
are “in-line” while the pin designations of an IDC connector are “even and odd”.
Pins 1 and 2 correspond to the X+ and X- signal respectively. These should be connected to the
X+ and X- input on the X-axis scanner amplifier.
Pins 3 and 4 correspond to the Y+ and Y- signals respectively. These should be connected to the
Y+ and Y- input on the Y-axis scanner amplifier.
Note: There should NOT be a connection to the “signal ground” of any scanner amplifier. The only
“ground” connection to the scanner amplifier (or amplifiers) should be from the power supply itself.
Connecting to the “signal ground” on a scanner amplifier will introduce a ground loop, which may cause
distorted images. See the “Power and X-Y Position Signal Connections” on the following pages.
Pins 5 and 6 correspond to the Intensity/Blanking+ and Intensity/Blanking – signals respectively.
These may be used for a single-color projector or projectors that use a PCAOM for color.
Pins 7 and 8 correspond to the Projector Interlock loop pins 4 and 17 from the ILDA connector.
Note that PASS will interrupt this interlock signal loop in the event of a critical fault and
when power is insufficient, therefore it is MANDATORY that projector manufacturers
implement an interlock scheme that makes use of these signals. Ideally this interlock loop
should interrupt power to the lasers themselves, thus, in the event of a major problem, PASS can
interrupt power to the lasers. Alternatively the interlock loop may be routed to a SEPARATE shutter
placed just before the X-Y scanners and after the PASS light sensor.
Pins 9 and 10 correspond to Red+ and Red – color signals respectively. These should be
connected to the RED input on a PCAOM driver or directly to a laser diode driver.
Pins 11 and 12 correspond to Green+ and Green – color signals respectively. These should be
connected to the GREEN input on a PCAOM driver or directly to a laser diode driver.
Pins 13 and 14 correspond to Blue+ and Blue – color signals respectively. These should be
connected to the BLUE input on a PCAOM driver or directly to a laser diode driver.
Pins 15 and 16 correspond to Deep Blue+ and Deep Blue – color signals respectively. These are
most often not used by modern RGB laser projectors and thus, can be left unconnected. If they are
used, they should be connected to the DEEP BLUE input on a PCAOM driver or directly to a laser
diode driver.
Pins 17 and 18 correspond to Yellow+ and Yellow – color signals respectively. These are most
often not used by modern RGB laser projectors and thus, can be left unconnected. If they are used,
they should be connected to the YELLOW input on a PCAOM driver or directly to a laser diode
driver.
Pins 19 and 20 correspond to Cyan+ and Cyan – color signals respectively. These are most often
not used by modern RGB laser projectors and thus, can be left unconnected. If they are used, they

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should be connected to the CYAN input on a PCAOM driver or directly to a laser diode driver.
Note that for the color signals above, ideally, any Laser Diode Driver should have differential input, and
you should connect both the + and – color signals from the PASS board directly to those drivers.
Pins 21 and 22 correspond to the Z+ and Z – signals respectively. In most cases, laser projectors
do not use these signals directly and in fact, when used with certain pieces of Pangolin software,
these signals correspond to a Safety Coordinate System. It is recommended that these be left
unconnected.
Pin 23 is connected to the ILDA input connector pin 12. This signal is reserved by ILDA for a light
sensor output, but it is essentially unused by all manufacturers. It is recommended that this pin be
left unconnected.
Pin 24 is connected to the ground connection of PASS. It is recommended that this only be used as
a ground reference for the shutter driver, and nothing else.
Pin 25 is the main Shutter output. Under normal circumstances the state of this signal will
correspond directly to pin 13 on an ILDA input connector. However, in the event of a major fault,
PASS will forcibly close the shutter using this signal. It is therefore MANDATORY that this be
connected to a shutter driver. For maximum safety, the shutter should be a fast type of shutter,
and one that also will fail-safe. This means that in the event of a mechanical or electrical failure of
the shutter, it will remain closed due to the mechanical design of the shutter. Pangolin highly
recommends shutters manufactured by the company called nm Laser Products
(http://www.nmlaser.com).
J803: Scanner Position and Light Detector Inputs
Pin 1 provides +5V output, which should only be connected to the PASS light sensor.
Pin 2 is the PASS light sensor input, which ranges from 0V to +5V.
Pin 3 and Pin 5 correspond to the Signal Ground connection of PASS. Pin 3 should be connected
to the PASS light sensor. Pin 5 may or may not be connected to the scanner amplifier, depending
on circumstances described below.
Pin 4 corresponds to the X Position Signal. This should be connected to the X-axis scanner
amplifier.
Pin 6 corresponds to the Y Position Signal. This should be connected to the Y-axis scanner
amplifier.
J804: Control Panel Signals

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PASS may be controlled by, and may illuminate LEDs on an external control panel that is connected to
PASS. Below is a description of the control panel connections. When PASS is not connected to an external
control panel, then PASS will automatically reset into a “ready” state shortly after power up. When PASS
is connected to an external control panel, then PASS will not power up in a “ready” state and instead, will
wait for the “Manual Reset” from the control panel.
Note that some jurisdictions including the U.S.A. require a manual reset in order to activate the projector
after power up. The PASS control panel connector may be used to help facilitate this feature.
Also note that the signals presented to this connector are generally connected directly to PASS logic
circuits. The signals are not protected from ESD or other electrical faults. For that reason, it is
recommended that any external signals that are connected to this connector be short (i.e. don’t connect
a 30 meter long cable from the external box to the PASS board…)
Pin 1 is the active input that corresponds to an external Emergency Stop (ESTOP) switch, such as a
pushbutton or red “mushroom” type switch. When this pin is connected to Pin 2 (ground), ESTOP is
activated. When Pin 1 is left floating, then ESTOP is inactive and the projector will be allowed to
operate normally.
Pin 3 is the active input that corresponds to a Manual Reset. This may be connected to pin 4
(ground) through a momentary pushbutton switch or a key-switch.
Pin 5 is an active input that indicates that a control panel is being used. Pin 5 must be connected
to Pin 6 when a control panel is used. If Pin 5 is not connected to Pin 6, then PASS will not wait for a
manual reset when power is first applied.
Pins 7 and 8 provide +5V to the control panel. These may be used in conjunction with LEDs on the
control panel.
Pins 9 and 10 correspond to Ground. These may also be used in conjunction with LEDs on the
control panel.
Pin 11 is an output, which corresponds to the horizon detector within PASS. If this signal is LOW, it
indicates that the Y position is below the horizon (within the audience area). If this signal is HIGH
(approximately 4 volts), it indicates that the Y position is above the horizon. This signal may be
routed through a resistor to an LED or pair of LEDs (bi-color pair) to give an indication on the
control panel as to where the beam is within the Y space.
Pin 13 is an output, which corresponds to the velocity detector within PASS. If this signal is LOW, it

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indicates that the beam velocity is OK, and that PASS will not actively suppress laser output
because of velocity (PASS may suppress laser output for other reasons however). If this signal is
HIGH (approximately 4 volts), it indicates that the beam velocity is too slow, and that PASS will
actively suppress laser output. This signal may be routed through a resistor to an LED or pair of
LEDs (bi-color pair) to give an indication on the control panel as to the disposition of the velocity.
Pin 15 is an output, which corresponds to the light detector within PASS. If this signal is LOW, it
indicates that the light that is detected by PASS is above the “Maximum Safe Laser Power”
threshold setting. If this signal is HIGH (approximately 4 volts), it indicates that the light detected is
below the “Maximum Safe Laser Power” threshold setting. Under ordinary circumstances, this will
never be LOW. This signal may be routed through a resistor to an LED or pair of LEDs (bi-color pair)
to give an indication on the control panel as to the disposition of the light detected by the light
sensor.
Pin 17 is an output, which corresponds to whether or not PASS is “ready”. Once PASS has given a
“armed” indication on Pin 19, and then once the “Manual Reset” is activated (by connecting Pin 3
to Pin 4), this signal will go HIGH, indicating that PASS will allow color signals to flow through the
PASS board to the internal laser projector components. This signal will remain HIGH as long as
there are no major faults detected, such as a Power Supply fault, Light Detector fault, other
detectable major fault, or ESTOP being activated. This signal may be routed through a resistor to
an LED or pair of LEDs (bi-color pair) to give an indication on the control panel as to whether or not
PASS is active.
Pin 19 is an output, which corresponds to whether or not PASS is ready to be activated (“armed”).
If this signal is HIGH, it indicates that the power supply is OK, ESTOP is not activated, and light is
not detected and thus, PASS may be activated by performing a “Manual Reset”. This signal may be
routed through a resistor to an LED or pair of LEDs (bi-color pair) to give an indication on the
control panel as to whether or not a Manual Reset can be performed. If used, this LED should
ideally be placed near the “Manual Reset” push button or keyswitch.
Pin 12 is an output, which corresponds to whether or not the computer feeding the ILDA input has
commanded that light come out of the laser projector or not. If this signal is HIGH, it indicates that
the light that PASS has detected that the computer has requested more than approximately 50%
beam power from the computer. If this signal is LOW, it indicates that the computer is commanding
50% or less beam power from the computer. This signal may be routed through a resistor to an
LED or pair of LEDs (bi-color pair) to give an indication on the control panel as to whether or not the
computer has commanded light to come out of the projector.
Pin 14 is an output, which corresponds to the condition of the power supply, both within PASS and
supplying the scanner amplifiers. If this signal is HIGH, it indicates that the power supply feeding
the scanner amplifiers is 19 volts or higher. It also indicates that all of the power supplies within
PASS itself are also within their acceptable ranges. If this signal is LOW, it indicates that there is a
power supply problem of some kind. This signal may be routed through a resistor to an LED or pair
of LEDs (bi- color pair) to give an indication of the state of the power supplies.
Status LED signals on the Control Panel connector
Pin 16 is a “Status LED number 1”. If this signal is LOW, it indicates that a power supply fault has
been detected.
Pin 18 is a “Status LED number 2”. If this signal is LOW, it indicates that the PASS light sensor
detected a light level that exceeded the “Maximum Safe Light Level” while the Y position was
below the horizon.

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Pin 20 is a “Status LED number 3”. If this signal is LOW, it indicates that PASS tried to extinguish
light from coming out of the projector, but that the PASS light detector still detected light output.
This would occur if a PCAOM or Laser Diode Driver continued to output light after being told not to.
This would also occur if the “Minimum light level” adjustment of PASS is not set correctly. And
finally, this might also occur if PASS did not detect light coming out of the computer even though
the computer commanded light output. This would indicate either a laser failure or light detector
failure.
Note that unlike the other LED outputs on the control panel connector, the “Status LED” outputs will
“latch” in the event that a fault is detected. They will remain in the latched state until a Manual Reset
occurs. This allows you to determine the cause of any detected faults.
The “Status LED” signals may be routed through a resistor to an LED on the control panel to give an
indication of any faults that have been detected.
PASS Power and X-Y position signal connections
PASS monitors the power supplies that feed the scanner amplifiers. This voltage can be between +/-20
volts and +/- 30 volts. The manor in which you connect PASS to the power supply and to the scanner
amplifiers depends heavily upon whether you are using two separate single-axis scanner amplifiers, or
one dual-axis scanner amplifier.
If you are using two separate single-axis scanner amplifiers, the recommended connections are shown

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below:
Note that each scanner amplifier, as well as the PASS circuit board itself must each have their own power
wires going back to the power supply. These wires should all meet at the power supply itself. If you have
two power supplies (one for +24V and the other for –24V) then these power supplies should establish a
central connection where all wires meet. This is called a “single-point grounding scheme. Wiring the
power supply in any other way will cause a ground loop, which may cause distorted images during
projection.
Also note that when using two separate single-axis scanner amplifiers, you run only the POSITION signal
to the PASS position input. DO NOT connect any additional ground wire from each scanner amplifier to
the PASS board. Doing so would introduce a ground loop, which may cause distorted images.
If you are using a one dual-axis scanner amplifier, the recommended connections are shown below:
Since there is only one scanner amplifier in this case, the scanner amplifier is connected directly to the
power supply. If you have two separate power supplies (one for +24V and one for –24V), these can be
connected at the scanner amplifier itself. The PASS board is also connected at the scanner amplifier
itself.
Note that in this case, it is permitted to connect a separate “position signal ground” from the scanner
amplifier to the PASS board if you wish.
PASS Switches
PASS includes a number of switches that must be configured to customize operation to a particular
projector or projection scenario. Below you will see the PASS board and location of the switches. The
operation of each switch is described below.

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With the PASS board in the physical orientation shown above, Switch 4 is at the top. When this
switch is moved to the left (on), the light sensor input is ignored. You should move the switch
to this position only during the setup operation described below, or in those rare
circumstances that PASS could legitimately be used without a light sensor. When this
switch is moved to the right (off), the light sensor input is monitored, and the maximum level of
safety is provided.
With the PASS board in the physical orientation shown above, Switch 3 is next in line. When this
switch is moved to the left (on), the Horizon control is monitored and PASS will only allow static or
slow beams above the horizon. If there is a slow-moving, or non-moving beam below the horizon, it
will be extinguished by PASS. When this switch is moved to the right (off), the Horizon control is
ignored, and PASS will not allow a slow-moving or non- moving beam anywhere within the entire
scan field.
With the PASS board in this orientation, Switch 2 is next in line. This switch controls the
interpretation of an advanced feature of PASS called the S-coordinate. At this time, we recommend
this switch be placed in the left position (on).
With the PASS board in this orientation, Switch 1 is on the bottom. This switch controls where PASS
gets the light sensor signal. ILDA pin 12 is defined by the ILDA standard as possibly providing
feedback from a light sensor. However, since the vast majority of projectors do not use this part of

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the ILDA standard, we recommend that this switch be moved to the right (off).
PASS Adjustment Potentiometers
As was the case with the switches, PASS includes five potentiometers that must be adjusted to customize
the operation of PASS to a particular projector or projection scenario. Below you will see the PASS board
and location of the five adjustment potentiometers. The operation of each potentiometer is described
below.
The Minimum Velocity controls the minimum speed that the beam is required to sweep, in X
and/or Y, in order to be considered to be safe. At the factory, Pangolin sets this to around 5 radians
per second. Note that the scale of this control (in radians per second) depends on the actual
position scale factor of the scanner amplifier being used. Turning this control clockwise increases
the minimum velocity (requiring faster scanning in order to be considered safe).
The Dwell Time controls the time that a beam may remain at or below the minimum velocity,
before PASS extinguishes the beam. At the factory, Pangolin sets this to around 1.5 milliseconds,
but you must adjust this yourself by using a calibration procedure, such as the one described
below. Turning this control counter-clockwise reduces the Dwell Time, and turning this control

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clockwise increases it. The Dwell Time can be adjusted between approximately 100 microseconds
and 10 milliseconds.
The Horizon adjusts the “Protected Area” (if Switch 3 is moved to the “on” position). At the
factory, Pangolin sets this control to approximately the center of the vertical scan field, but this
may be adjusted clockwise or counter-clockwise to set the horizon of the protected area as desired.
Note that this control is very sensitive to rotation. You will not need to turn this control very much
to explore the entire vertical area. Also note that the horizon adjustment is completely ignored if
Switch 3 is turned off. (See the section about PASS Switches for more information.)
The “Maximum Safe Beam Power” adjustment controls the maximum power that can be allowed
into the “Protected Area”. For example, if the beam is scanning within the audience area, PASS will
monitor the beam power and make sure that this beam power is not exceeded. If the beam is not
scanning within the “Protected Area” (for example, above the horizon), then this control is ignored
and full-power beams can be projected overhead.
The “Minimum Power” adjustment controls the minimum light level that is detectable by the light
sensor. Generally this is adjusted so that no light is detected by PASS when the laser is off.
You can adjust the “Maximum Safe Beam Power” and “Minimum Power” adjustments by looking at D208
“Light Sensor State” bi-color LED on the PASS board.
Also note that the “Maximum Safe Beam Power” and “Minimum Power” adjustments are ignored if the
switch 4 is turned “on” (see switches on page 20).
PASS Adjustment Procedure
NOTE: The information contained in this section must be understood and followed very
carefully in order to ensure that PASS operates correctly, and to minimize the risk of an
unsafe laser exposure.
Since the procedure described below involves projecting patterns into an area that an audience will
eventually occupy, and since the light levels experienced during adjustment procedure may exceed the
MPE under some circumstances, it is highly recommended that you perform the procedure below when
the venue is only occupied by trained technical staff, and communicate very clearly when the laser will
be turned on so that staff will know how to react. To avoid the possibility of illuminating people who may
not understand the technology or potential risks that a laser projector may present, the adjustments and
procedures described below should preferably be done in a laboratory environment, not in the venue
where personnel (for example waitresses, etc.) may be walking around before the venue opens.
Step 1: Adjust the Horizon (whether you will ultimately use it or not)
During this first test, it is important to use the lowest amount of laser power possible. This will reduce the
chance of illuminating personnel that might be in the room during these tests. For the next few tests and
adjustments, the beam power is best reduced by using the software brightness level setting – rather than
potentiometers that might reside on the back of a laser projector.
First, set PASS Switch 3 to “Protect only the bottom portion” (switch moved to the left, if the board is

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physically oriented as shown on Page 20). Also, set Switch 4 to “Light sensor not used” (switch moved to
the left.) These switch positions are necessary for the next few adjustments.
Next, output a slow-moving circle (for example, somewhere in the 1Hz to 5Hz range) using a function
generator or abstract generator feature of the software. The circle should be somewhere between 50%
and 100% size for this test. Note that while doing this and if PASS is not set correctly, the laser beam will
probably be allowed to enter the audience area. Therefore it is once again important to make sure there
are no untrained or non-technical personnel present in the room during this setup.
At this point and with this kind of pattern being projected, you should see that – while the beam is above
the audience area, it is visible, and while the beam is within the audience area, it is extinguished. If you
do not see this, then it is possible that the Horizon potentiometer is set so far in one direction, that PASS
thinks the entire scan field is above the horizon. In such a case, turn the Horizon potentiometer several
turns clockwise, and then several turns counterclockwise, until you see that there is an area where the
beam is blanked. If you never reach a point where the beam is not extinguished, then stop right there
and make sure PASS is wired correctly – particularly with respect to the scanner position signals.
Next, adjust the Horizon potentiometer clockwise, and counter- clockwise, to position the area (horizon)
such that the beam is extinguished when it is in the audience area.
Once this is done with the slow-moving circle, COLLAPSE the Y axis (change Y size to zero in the
software), which will project essentially a slow-moving horizontal beam – centered on the Y-axis. You will
want to make sure that the beam is extinguished in this configuration, because it is important when the
projector has no scanning input (i.e. X and Y projector inputs at zero) that no light will come out of the
projector.
Now adjust the Y position control in the software upward, to the point where the beam becomes visible
again. You want this to be at least 2% upward. If the beam becomes visible at 1% upward position on Y,
adjust the Horizon control again to extinguish the beam.
Once the Horizon is verified above, return the Y position control in the software to 0.
Step 2: Determine the Maximum Beam Power allowable in the audience area
Now that the PASS horizon has been adjusted, it can be used to aid in preparing to evaluate the
maximum laser power that will be allowed in the audience.
At this point it will be necessary to configure the software to output a stationary, non-modulated laser
beam. In LD2000 this can be done by going to the Abstract Generator (menu SFX/Abstract Generator),
and then reducing the size of the default abstract to zero, and then pressing OK.
If you have adjusted the horizon properly, you should see NOTHING coming out of the laser projector.
Otherwise, go back and repeat the steps above, ensuring that the Horizon potentiometer is adjusted
properly.
Since the point is to determine the maximum amount of laser power that will be safe in the audience,
this should be done with any projector-based power-level adjustments defeated. For example, if the
projector has potentiometers (or digital adjustments) accessible from the rear, that can be used to

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reduce the beam power, these adjustments should be set all the way at maximum, so that the power
level coming out of the laser projector is entirely controlled by the software input.
Now – in the Projector Settings dialog box, make sure that the brightness level is turned down – perhaps
to 10%.
Slowly move the Y Position control upward, until the beam hopefully becomes visible. If the beam does
not become visible after a substantial upward movement of Y Position, then adjust the brightness level
upward until a beam is seen.
Now, using a laser power meter that has a 1 square centimeter (or approximately 11mm round) detector,
place the detector of the power meter into the stationary beam – AT THE CLOSEST POINT OF AUDIENCE
ACCESS. It might be handy to mount the detector head of the power meter onto a tripod stand, so that it
can be held into the stationary beam.
The laser beam should be larger than the 1 square centimeter power meter detector area. If it is not,
then you will need to increase the divergence of the laser beam, for example, using one of Pangolin’s
SafetyScan lenses. (A beam smaller than 11mm round in the audience will certainly not be safe, unless
the power is around 10 milliwats…)
When the laser beam is larger than the 1 square centimeter active area on the power meter, then the
power meter will read in terms of Watts Per Square Centimeter (also known as “irradiance”), instead of
Watts (also known as “radiant power”). This is an important concept that must be understood. The laser
safety standards are based on irradiance, not radiant power!
Using the software brightness control, increase the beam power upward and upward and upward until
the laser power meter reads the desired level of irradiance – according to the MPE that you are trying to
accomplish. Although PASS allows for a large degree of adjustment, laser industry best practices
generally assume that the irradiance will be no greater than 10 milliwatts per square centimeter for a 1
millisecond pulse width described below.
Now that you have determined the maximum brightness level that the software can output to accomplish
the desired irradiance, you should write this down on a piece of paper, or otherwise record it. For
example, this might be a brightness level of 27%. This means that you will need to paint a brightness
level of 27% into the Beam Attenuation Map, or use other software features to ensure that the beam
power never exceeds the maximum safe power level determined in this step.
Step 3: Enable the light sensor, and adjust the Maximum Beam Power
potentiometer
Adjust the Maximum Beam Power potentiometer on PASS, many turns clockwise. The idea is to set this to
a level that won’t immediately trip once you enable it using Switch 4.
Now, go to the Abstract Generator and increase the size to project a circle. Any other pattern may be
projected, but it’s best to keep the pattern simple.
If you have done everything correctly and followed the instructions carefully, at this point you should see

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Complete Help Docs - https://wiki.pangolin.com/
a circle or pattern projected at what is essentially the maximum power that it will ever be in the
audience.
Next, using the brightness level setting in the software, increase it a one percent past the level
determined above. For example, if the maximum safe power was determined to be 27% brightness, you
should increase the brightness level setting to around 28%. This should output a power level a bit higher
than the maximum determined in the step above.
Next, enable the light sensor by moving PASS Switch 4 to the “Light sensor is used” setting (switch
moved to the right).
Next, slowly turn the Maximum Safe Power potentiometer counterclockwise, until PASS “trips”. Basically
what you are doing in this adjustment is bringing the threshold down to the point where PASS will trip if it
detects more beam power than was determined to be safe above.
Once PASS has “tripped”, it will need to be reset, either using the Manual Reset pins on the control panel
connector, or by cycling power to the projector.
Before resetting PASS using control panel pins (or cycling power to the projector), reduce the brightness
level setting in the software back to the level determined above (for example, 27%).
Once the projector is running again, you can verify the “trip” level, by adjusting the brightness level
upward until it trips. We also recommend that you run a number of test patterns and show program
material with the brightness set to the maximum safe power determined above (i.e. 27%). If the projector
occasionally trips, then you might want to examine any filter or combiners used to “flatten” the spectral
response curve of the light detector used in your projector. If PASS trips repeatedly, you may need to
reduce the brightness level determined above (for example to 26% or so)…
Step 4: Set PASS Switch 3 to the desired position
If it is your intention for PASS to protect the entire scan field, then now would be the time to move Switch
3 “Protect entire scanfield” position (to the right). Otherwise you can simply leave the switch where it is.
Preparing to perform further measurements and adjustments
At this point you will be adjusting the velocity detector and dwell timers inside PASS. To do this, connect
a fast photodiode to an oscilloscope. The photodiode should be the amplified type, so that the
oscilloscope will show voltage as a result of light entering the detector. The Thor Labs model PDA100A is
a good choice for an amplified photodiode.
A 7mm aperture must be placed in front of the photodiode entrance aperture. This might be done by
cutting a 7mm hole in a piece of “Black Wrap” foil, and then placing this over the entrance aperture. The
7mm pupil allows the photodiode to measure the pulse width as a scanning beam crosses a 7mm dilated
pupil.
The photodiode should be placed on a tripod, so that it can be moved into the beam path to perform
safety-related measurements.

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Once the photodiode is prepared as described above, use a function generator or software’s built-in
ability to project a circle. The circle should preferably be continuous, and non-modulated. In LD2000 this
is easily accomplished using the Abstract Generator. (Just go to SFX/Abstract Generator, and click OK.)
The size of the circle should be such that it scans within the area where the audience will reside.
As with some of the tests above, during these tests, it is important to use the lowest amount
of laser power possible. This will avoid overloading the photodiode and also reduce the
chance of illuminating personnel who might be in the room during these tests.
Move the tripod and photodetector such that the circle scans across the 7m aperture – AT THE CLOSEST
POINT OF AUDIENCE ACCESS – and look at the output on the oscilloscope. Preferably, the photodiode is
positioned roughly in the center of the beam path as it scans past the detector. This should also be the
brightest part of the beam. You should be careful, and be aware that photodiodes have shiny surfaces
which can create mirror-like back-reflections. Therefore you must be very careful while placing the
photodiode into the beam path, that the reflected stray beam will not accidentally wind up targeting
personnel or an undesired location.
Adjust the voltage input and time setting on the oscilloscope so that you can measure the height (i.e.
maximum voltage) of the pulses. During this part of the test, it is very important to make sure that the
photodiode is not overloaded with light, and merely delivering a “saturated” maximum voltage to the
oscilloscope, as this will artificially lengthen the pulse width. The PDA100A photodiode has an attenuator
dial on the side to adjust the gain. Make sure that this gain setting is adjusted properly, so that the
photodiode is not overloaded.
Step 5: Adjust the Minimum Velocity potentiometer
Once you have a reliable voltage measurement, the pulse width is determined at the “full width at half
maximum” points on the waveform. For example, if the voltage waveform slopes from 0 volts upward to
4 volts, and then downward to 0 volts, essentially this means that the pulse width is the amount of time
that the pulse is greater than 2 volts.
Since laser industry best practices are that audience scanning shows are done using the assumption of a
1-millisecond maximum pulse width, you should compare this against the pulse width seen on the
oscilloscope. If the pulse width is shorter than 1 millisecond, then you will need to slow down the function
generator (or Pangolin software abstract generator) until you get to a pulse width of 1 millisecond.
Generally, PASS should be adjusted to extinguish the laser beam for pulse widths greater than 1
millisecond. If you are able to slow down the function generator to obtain longer pulses, then this means
that the MINIMUM VELOCITY adjustment on PASS must be increased (turned clockwise).
Step 6: Adjust the Maximum Dwell Time potentiometer
Now that the Minimum Velocity adjustment has been setup, you can move to the next part of the test,
which ensures that the Maximum Dwell Time is adjusted properly. To do this, change the test pattern
from a circle to a Quadrature Squarewave. (A Quadrature Squarewave is a pattern where the beam stops
in four places, and jumps very quickly from place to place. The Abstract Generator in LD2000 has a drop-

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down list box where you can select the waveform that will be used.)
Move the photodiode and tripod into one of the corners of the quadrature squarewave, taking all of the
precautions mentioned above. Adjust the voltage level on the oscilloscope, and adjust the attenuator dial
on the photodiode to ensure that you have a reliable voltage measurement.
As described above, determine the pulse width at the “full width half maximum” points on the waveform.
If the pulse width exceeds 1 millisecond, adjust the MAXIMUM DWELL TIME potentiometer
counterclockwise.
Using PASS with a light sensor
When PASS is used with the “LIGHT SENSOR USED” switch setting, then a light sensor must be connected
to J803 Pin 1, Pin2, and Pin 3.
When a light sensor is not used, J803 Pin 2 should be connected to Pin 1. Note: it should be
understood that using PASS without a light sensor should only be allowed if you are using
the PASS hardware as a simple scan-fail safeguard AND if the laser power is low enough to
justify this AND if you implement additional safety-related systems down-stream from the
PASS hardware. Contact Pangolin for more information if you are interested in using PASS
without a light sensor.
When used, a light sensor must be installed within the beam path of the projector. Generally we
recommend that the light sensor be placed before the final shutter, but it may also be placed after, as
long as the final shutter opens faster than around 1/20th of a second.
Generally the light sensor is fashioned as a glass window that is used to “sample” the outgoing laser
beam at a 45-degree (or so) angle, and direct a small portion of the laser beam to light-sensitive
material.
The light sensor used with PASS must be a relatively fast sensor – one that is able to react as quickly as
the light can be modulated. Generally this means that the light-sensor must be based on silicon
photodiode or silicon PIN photodiode type technology.
If the projector is a multi-wavelength projector (e.g. an RGB projector), and a single light sensor is used in
the combined beam path, then the light sensor must have an additional “spectral flattening” filter to
make the light sensor provide the same output for all wavelengths. This is because the safety standards
treat all visible wavelengths the same. Since silicon detectors have a peak response in the near infrared
and since their response tends to trail off toward the visible blue spectrum, this filter appears to the
naked eye as a bluish piece of glass – allowing light in the blue end of the spectrum to pass freely, while
attenuating longer wavelengths more progressively. These tend to be specialized filters, generally
matched to a particular photodiode, and therefore we have not found a place that sells just the filter by
itself.
An alternative to using a single sensor in the combined beam path would be to put individual light
sensors after each separate- wavelength laser, and sum the output of all of the light sensors so that the
total output voltage sent to PASS corresponds linearly with wattage (i.e. delivers the same amount of

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voltage for the same amount of power from each separate wavelength).
The output of silicon photodiodes cannot be directly connected to PASS. Instead the photodiode output
must be amplified, and turned into a zero-to-5-volt analog signal, where zero volts represents no light
being detected and 5 volts represents the maximum voltage delivered to PASS. Note that PASS provides
a connector with 5 volts, so this is where the light sensor and amplifier can get its power.
Since PASS has adjustments for MINIMUM POWER and MAXIMUM SAFE POWER (see page 22), the output
of the sensor does not need to reach all the way to 5 volts when maximum light is coming out of the
projector. Likewise, the sensor may deliver 5 volts even before the maximum light power level is
reached. Any maximum-light-output scale factor can be used as long as around 4 volts or less represents
the maximum safe light level for audience scanning (which would generally be lower than 1 watt, but
could be more depending on the distance of the projector to the audience and other factors).
Under the most ideal circumstance, the photodiode should be amplified with a logarithmic amplifier (also
called “log-amp”), because when this is done, the voltage output from the amplifier will correspond to
light power (i.e. watts), not just light intensity. However, a simple op-amp amplifier may be used, as long
as it has enough dynamic range that a few milliwatts of power delivers a detectable voltage level (and
can satisfy the “MINIMUM POWER” adjustment) and also maximum safe light level is reached before
around 4 volts.
Presently, the only ready-made product that is readily available on the market, which has a silicon
detector with the “spectral flattening” filter attached and logarithmic amplifier board is the model SEL033
detector with model F “flat response” filer, and model A430 amplifier, all available from International
Light Technologies corporation. Note that these components are generally not stocked items, and
normally they have to be pre-ordered from the company. Also note that these are large and bulky, so
they may not be appropriate for compact projectors. And finally the combination of these parts does not
constitute a complete light sensor ready to be used in a laser projector. The sampling window and
mounting hardware are additional items that need to be fashioned within the projector to create a whole
light sensor package.
Using a light sensor with PASS can be tricky. When you enable the light sensor feature in PASS,
everything must be at least ready to operate correctly. Otherwise PASS will detect problems and “trip” –
forcibly shutting the projector down, requiring either a manual reset (i.e. by briefly shorting pin 3 to pin 4
on the Control Panel Connector) or the power being re-cycled.
PASS will forcibly shut the projector down under the following critical circumstances:
A voltage level less than the “MINIMUM POWER” adjustment indicates, being detected when the
software (via the color lines on the ILDA connector) commands light to be coming from the
projector.
A voltage level greater than the “MINIMUM POWER” adjustment indicates, being detected when the
software (through the color and intensity lines) indicates that the output is supposed to be blanked.
A voltage level greater than the “MAXIMUM SAFE POWER” being detected when the beam is
projected within an audience area. Of course the audience area may be the entire projected area,
or only the lower portion of the scan field, depending on the “PROTECTED AREA” switch setting
Using the light sensor with PASS affords the maximum level of protection, because if the laser power is
increased above the MAXIMUM SAFE POWER within the designated audience area (i.e. the entire scan