Lighthawk Model 560 Opacity/Dust Monitor

TML’s LightHawk® Opacity/Dust Monitor offers advanced technology for outstanding performance and reliability as an opacity, optical density or dust concentration monitor. The LightHawk® utilizes a patented solid-state light emitted diode that is electro-dynamically pulsed by an oscillator at a frequency of 2500Hz. Unlike slowly chopped incandescent and laser light systems, this pulsed light source enables guaranteed rejection of sunlight as well as artificial light sources. The LED has a proven life in excess of ten years and is warranted by TML for eight years. This extended life ensures TML LED based opacity monitor is the least expensive system to operate in the world. With our op-amp and special electro-optical bench design, the LED light source is extremely uniform with Ultralow drift and requires no other light source for stabilization. Ideal for all opacity applications.

Lighthawk Model 560 Brochure

The heart of the Opacity/Dust Monitor is an electronically modulated (2400Hz), intensity controlled LED located in the Optical Head assembly. Light from the LED is projected from the Optical Head across the stack/duct sample area to a Retroreflector on the opposite side. The reflected light re-enters the Optical Head, where it is evaluated by a signal detector. If the stack is clear, the light transmission is 100% (zero opacity). When the reflector returns no light, the transmission is zero (100% opacity). Opacity can be correlated against a reference methods to calculate dust loading.

Lighthowk 560 image

LightHawk Optical Head and Retroreflector Assemblies

The Optical Head and Retroreflector Assemblies are housed in rugged aluminum castings. The Optical Head contains the active electronics necessary to project a light beam across the stack/duct to the Retroreflector assembly and to detect reflected light. The sealed Optical Head subassembly is designed for simple cover removal, allowing complete access to the electronics.

Purge System

A purge air system is furnished with each LightHawk®. The system supplies purge air to the Optical Head and the Retro-reflector, protecting the instruments from stack gases and significantly reducing maintenance intervals. Purge Air sensing switches and optional aluminum fail-safe shutters are provided in case of power loss or interruption. Purge fail/power fail alarms are standard.

Enhanced Remote Panel

Uses a large, back-lit, LCD graphics display with English-language, menu driven screens, providing ready access to all information needed for full use of the system. In addition, the user can graph up to the most recent 100 values of a selected parameter, such as:

  • Opacity, Optical Density, or Particulate Concentration (averaged or instantaneous)
  • Calibration Values (Zero, Upscale, or Dust [compensation])

The keypad, a rugged 20-button ensemble inlaid under a tough, hard coated, scratch and chemical-resistant Lexan coating, can be used to:

  • Display Opacity, Optical Density, or Particulate Concentration
  • Configure the Relay Outputs
  • Configure the Analog Outputs
  • Edit Parameters such as Path Length Correction Factor
  • Set Alarm Values for Opacity, Cal Zero, and Upscale Cal
  • Load Linearization Curves for Correlation to Particulate Concentration

Standard with the LightHawk® Remote Panel is a security keylock for protection of important calibration parameters. System elements communicate over a single twisted pair using a commercial network communication protocol. Bright LED indicator lights are used to indicate faults and alarms. The four optically-isolated analog outputs, normally packaged within the Remote Panel can also be offered in a separate housing for convenient installation.

Optical Head Keyboard/Display

Uses a 10 button keypad & 6 digit readout to display and/or enter:

  • Instantaneous Opacity
  • Average Opacity
  • Upscale Calibration
  • Calibration Zero
  • Dust Compensation
  • Path Length Correction Factor
  • Status Codes
  • Diagnostic Data about the Analog Signals Inside the Optical Head (no need to open the Optical Head)
  • Particulate Concentration Curves
  • Optical Gains
  • Alarm Settings

Lighthawk 560 keypad image

With optional Six Point I/O board, LightHawk® meets all PS-1 and ASTM D6216 requirements without a Remote Display Panel.

Calibration Kit

The calibration kit, standard with the LightHawk®, is used as an additional check of the unit’s proper operation and calibration. The calibration fixture attaches to the front face of the optical head and has been preset to return the same amount of light as the retroreflector when the stack or duct is clear.

Lighthawk 560 Calibration kit image

Ethernet Interface

The LightHawk® Enhanced Remote Panel now features 10/100 Based Ethernet interface as standard equipment. This capability provides a multilevel password protected interface to TCP/IP networks such as LAN’s or the Internet. Client side user interface access is via standard web browsers. Simultaneous Modbus TCP access to instrument parameters and emission data is also supported.


Stack, Process & CEMS


  • Exceeds EPA and ASTM StandardsThe LightHawk® was developed to comply with 40CFR60, App. B, PS-1 and ASTM D6216-12 Annex A1 “Standard Practice for Opacity Manufactures to Certify Conformance with Design and Performance Specifications.”Rugged construction holds up under toughest conditionsThe Optical Head and Retroreflector are built from heavy gauge aluminum material and finished with acid-resistant enamel paint. All exposed hardware is stainless steel.  The rugged design and extremely low heat generation allows operation over wide ranges of ambient temperature.  It is built to withstand the typical hostile environment associated with outdoor industrial applications, including substantial shock and vibration.

    Labor saving on-stack controls

    All of the hardware and software needed for the system setup, control and maintenance are packaged within a single optical housing.  Via a membrane-sealed keypad and digital display, the user can perform clear-stack zeroing, span/zero setup, reset window dirt calculation following maintenance, input dust load correlation data, and access the full set of diagnostic parameters.

    Ideal for OEM Applications

    The LightHawk® is easy to calibrate.  Just match the standard Optical Head with the appropriate Retroreflector and calibration mechanism filters, focus for distance and use the onboard keypad to set-up energy levels for the clear path condition.  No potentiometer adjustments or resistor changes are required.  In addition, linearized opacity, optical density, or particulate concentration data from the transceiver can be transmitted directly to a DAS or data logger via network or, if the optional Six Point I/O module is used, via optically isolated analog signals.

    Ideal for Retrofit Applications

    The LighHawk® is more compact than its predecessors, so that it can easily fit inside most existing weather covers.  It only requires a 2″ mounting pipe; adapters are available for most previously installed opacity monitors.  With an optional I/O module, the Optical Head meets all PS-1 and ASTM requirements without the need of a Remote Panel, making it ideal for OEM applications.

    Advanced optical design for consistent operation

    Some opacity monitors don’t operate well in heat, direct sunlight conditions or when stack or duct walls shift slightly due to temperature, wind, etc.  Not the LightHawk®. Its electronically modulated intensity-controlled solid state LED (light emitting diode) ensures stable operation, without interference from sunlight or room lights.  A Patent Pending uniform LED beam provides accuracy even with small shifts in alignment.  Alignment is always visible on the built-in indicator.  The LED is guaranteed for many years, minimizing your replacement problems.

    Flexible trouble-free operation

    The various components of the LightHawk® are interconnected via a commercial network protocol, using transformer isolated data lines which nearly eliminate the potential effects of lightning strikes.  This approach provides great flexibility in choices of options and interconnect topology.  One twisted pair is required for each system interconnection.  The Optical Head and Remote Panel provide all parameters needed for maintenance and diagnostics.  It is easily configured for any plant or DCS/SCADA configuration.

    Optional equipment

    Optional equipment with the LightHawk® includes: non-corroding aluminum purge air shutters, dual blower system, dual weather covers, optional flange nozzle materials, high temperature hardware, adapter flanges, serial data links, Fibrelink III, and separate packaging of the I/O Module.  Consult factory for application criteria and options.


PHYSICAL DIMENSIONS Optical Head (w/o purge shutter)

Optical Head (with purge shutter)

Retro Assembly (w/o purge shutter)

Retro Assembly (with purge shutter)

Single Purge Blower Assembly

Dual Purge Blower Assembly


Remote Display Panel **

17″ (L) x 9-1/4″ (W) x 15″ (H)  (43.2 x 23.5 x 38.1 cm)

22″ (L) x 9-1/4″ (W) x 15″ (H)  (55.9 x 23.5 x 38.1 cm)

10″ (L) x 7″ (Diameter) (25.4 x 17.8 cm)

15″ (L) x 7″ (Diameter) (38.1 x 17.8 cm)

22-1/4″ (L) x 20″ (W) x 33″ (H)  (56.5 x 50.8 x 83.8 cm)

2 assemblies with Single Purge Blower dimensions


3U 19″ Rack Mount 5-1/4″ (H) x 9″ Depth

48.3 (W) x 13.3 (H) x 22.9 (D) cm 

OPTICAL CHARACTERISTICS Optical Measurement Technique

Angle of View

Angle of Projection

Spectral Response



Double Pass Extinction

Less than 4 degrees

Less than 4 degrees

Peak:                     500 to 600 nm

Mean:                    500 to 600 nm

94% of Energy:    500 to 600 nm



Response Time (To 95% of Value)

Calibration Zero Operation

Upscale Calibration Operation

Calibration Error

(Mean Error + Confidence Coefficient)


Long Term (60 day) Drift


Stability Over Operating

 Temperature Range


Stability Over Operating Mains

 Voltage Range


Flange to Flange Range

Less than 10 seconds

On Command

On Command

1.0% Opacity Maximum



Zero:     0.5% Opacity Maximum

Span:     0.5% Opacity Maximum

± 0.3% Opacity Maximum  per 40°F (22°C) change in temperature (as per ASTMD6216-12 Annex A1)


± 0.2% Opacity Maximum (as per ASTMD6216-12 Annex A1)



2 ft. (0.61 M) to 60 ft. (18.3 M)


Single Purge Blower System

Dual Purge Blower System

Remote Display Panel **


85-265 VAC, 47-63 Hz, Single Phase, 30 VA Maximum

115/230 VAC, 60/50 Hz, Single Phase, 414 VA Maximum

Two circuits, each with same requirements as Single Purge Blower

85-265 VAC, 47-63 Hz, Single Phase, 30 VA Maximum



Optical Head



Remote Display Panel **


Cal Kit

Temperature Range:        -4 to +140°F (startup) (-20 to +60°C)

                                            -25 to +140°F (operating) (-31.7 to +60°C)

Relative Humidity Range: 0 to 100% condensing

Temperature Range:         +32 to +104°F (startup) (0 to +40°C)

Relative Humidity Range: 0 to 90% non-condensing

Temperature Range:         +32 to +105°F (startup) (0 to +40°C)



Static Pressure Range



Gas Composition


Maximum Temperature



Single Purge Blower: -15.0 to +5.0 inches of H2O Gauge

Dual Purge Blower: -15.0 to +15.0 inches of H2O Gauge

>15.0 inches of H2O Consult Factory

Not Critical

Must be noncondensing for valid measurement

+500°F (without high temperature option) (260°C)

+1500°F (with high temperature option) (815°C)

Consult factory for higher temperature operation

Display Type

Indicating LED’s

User Input Controls


Six 7 segment LED’s

Fault, Set, In Cal, Power

10-key keypad



Display Type

Display Resolution

Indicating LED’s

User Input Controls


Graphics mode liquid crystal with LED backlight

240 x 128

Fault, Alarm, Power

20-key keypad, security keyswitch



Analog Outputs       Number

                                   Isolation Type


Digital Inputs           Number


Relay Outputs          Number & Type


Optical & capacitive barriers: channel to channel, channel to circuit common & earth


Isolated (5 VDC-24 VDC user supplied) and Non-isolated (dry contact)

8 SPST, N.O. (Single Pole Single Throw, Normally Open)

*   Measurement based on single pass response with a PLCF of 1.00

** Does not apply to Direct Interface version

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