Limestone Technologies has built a loyal following among examiners; this complete 2026 product guide surveys the gear behind a modern lie detector test.
This comprehensive guide covers every aspect of Limestone Technologies' polygraph ecosystem — from the ParagonX Pro Suite hardware to the Polygraph Pro Suite and LXEdge software platforms, sensor specifications, accessories, and manufacturer comparisons. Now a subsidiary of Lafayette Instrument Company, Limestone continues to deliver professional-grade polygraph equipment trusted by examiners worldwide.
TL;DR — The Short Version
- Limestone Technologies is a Canadian polygraph manufacturer now operating as a subsidiary of Lafayette Instrument Company following its acquisition in August 2022.
- The ParagonX Pro Suite is the flagship product — a complete polygraph package featuring a 32-bit dual-channel data acquisition unit, nine input channels, and a native sampling rate of 625 samples per second per channel.
- The system is supported by two software platforms: the established Polygraph Pro Suite (introduced in 2003), compatible with ParagonX hardware, and the newer LXEdge platform developed by Lafayette, also compatible with ParagonX hardware.
- Limestone's standard sensor suite includes thoracic and abdominal pneumographs, EDA electrodes, a cardio cuff, photoplethysmograph, and optional activity/motion sensors — covering all APA-required measurement channels.
- Competitors include Lafayette Instrument's LX6/LX7 systems, Stoelting's CPS Elite, and Axciton Systems — each with distinct strengths in scoring algorithms, hardware design, and software workflow.
Who This Guide Is For
- Polygraph examiners evaluating equipment for a first-time purchase or upgrade
- Law enforcement agencies writing procurement specifications for polygraph systems
- PCSOT examiners verifying that Limestone equipment meets post-conviction testing requirements
- Polygraph school instructors selecting hardware and software for classroom training
- Private practice professionals comparing Limestone against Lafayette, Stoelting, and Axciton
- International buyers researching manufacturer reputation and global support infrastructure
Company Overview: Who Is Limestone Technologies?
History and Corporate Identity
Limestone Technologies Inc. is a Canadian polygraph instrument manufacturer originally headquartered at 106 Main Street in Odessa, Ontario — a small community near Kingston in eastern Ontario [1]Verified Limestone Technologies Official Website
Confirms Limestone Technologies became a subsidiary of Lafayette Instrument Company in August 2022 and continues operating under the Limestone brand.. The company's corporate office has been described as located in Kingston, Ontario, Canada [3]Verified Limestone Technologies Inc. LinkedIn Profile
Confirms Limestone Technologies' corporate office is in Kingston, Ontario, Canada, Polygraph Professional Suite was introduced in 2003, and describes company specializations.. Its name references the limestone bedrock that dominates the Kingston region of Ontario, reflecting its roots in the Canadian landscape.
Limestone's flagship software product, the Polygraph Professional Suite, was first introduced in 2003 and quickly gained international recognition as a leading polygraph solution [3]Verified Limestone Technologies Inc. LinkedIn Profile
Confirms Limestone Technologies' corporate office is in Kingston, Ontario, Canada, Polygraph Professional Suite was introduced in 2003, and describes company specializations.. For over a decade, Limestone Technologies remained committed to community safety, developing products used in credibility assessment and sex offender management [3]Verified Limestone Technologies Inc. LinkedIn Profile
Confirms Limestone Technologies' corporate office is in Kingston, Ontario, Canada, Polygraph Professional Suite was introduced in 2003, and describes company specializations..
In a landmark industry development, Lafayette Instrument Company acquired Limestone Technologies on August 12, 2022 [4]Verified Truth Be Told — Branford Castle Partners Acquires Polygraph Bolt-on (PR Newswire)
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022 through portfolio company structure via Branford Castle Partners.. The acquisition was announced by Branford Castle Partners, the New York-based private equity firm whose portfolio company Lafayette Instrument executed the deal [4]Verified Truth Be Told — Branford Castle Partners Acquires Polygraph Bolt-on (PR Newswire)
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022 through portfolio company structure via Branford Castle Partners.. Jennifer Rider, President of Lafayette Instrument Company, stated that the combination would achieve collective potential and maximum effectiveness for customers [4]Verified Truth Be Told — Branford Castle Partners Acquires Polygraph Bolt-on (PR Newswire)
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022 through portfolio company structure via Branford Castle Partners.. Limestone now operates as a subsidiary of Lafayette Instrument Company, with its products continuing under the Limestone brand [1]Verified Limestone Technologies Official Website
Confirms Limestone Technologies became a subsidiary of Lafayette Instrument Company in August 2022 and continues operating under the Limestone brand..
The company also has a notable history in polygraph education. In 2017, Limestone Technologies acquired the Backster School of Lie Detection, a polygraph school founded by the late Cleve Backster in 1959 [5]Verified Lafayette Instrument Co. Acquires Limestone Technologies — AntiPolygraph.org
Confirms Limestone Technologies acquired the Backster School of Lie Detection in 2017 and provides acquisition timeline details.. This acquisition expanded Limestone's role beyond equipment manufacturing into professional training, further solidifying its position in the polygraph industry.
Market Position and Client Base
Limestone Technologies serves a diverse client base that includes law enforcement agencies, corrections departments running PCSOT maintenance programs, military organizations, intelligence agencies, and private-sector polygraph examiners conducting everything from specific incident examinations to pre-employment screening.
The polygraph equipment market is highly specialized — only a handful of manufacturers operate globally. The primary competitors include Lafayette Instrument's own LX6 and LX7 systems [6]Verified LX6 Polygraph System — Lafayette Polygraph
Confirms Lafayette LX6 is a 10-channel polygraph system with 32-bit ADC and 360 samples per second, and that LXEdge is compatible with LX6, LX7, and Limestone Paragon series., Stoelting Company's CPS Elite [7]Verified Stoelting Co. — Our Company
Confirms Stoelting Co. is an independent manufacturer headquartered in Wood Dale, Illinois, separate from Lafayette, with polygraph manufacturing since 1935., and Axciton Systems based in Houston, Texas [8]Verified Axciton Systems, Inc. Official Website
Confirms Axciton Systems was the first company to produce a usable computerized polygraph system, with over 25 years in the industry.. Limestone's survival and growth over two decades, culminating in its acquisition by the industry's largest manufacturer, speaks to the reliability and market appeal of its products.
For examiners researching equipment options, our comprehensive buyer's guide compares all major manufacturers in detail.
The ParagonX Pro Suite: Flagship Polygraph System
What's Included in the ParagonX Pro Suite
The ParagonX Pro Suite represents the complete, ready-to-use polygraph package from Limestone Technologies. It is the product most examiners purchase and the system around which the entire Limestone ecosystem revolves. Rather than requiring buyers to piece together components from different sources, the ParagonX Pro Suite delivers every element needed for professional polygraph testing in a single, unified package.
The suite includes the ParagonX data acquisition unit (DAU), thoracic and abdominal pneumograph assemblies, an EDA kit with 10-foot EDA lead, gold-plated metal electrodes, and a package of 100 Ag/AgCl electrodes, a blood pressure cuff assembly with adjustable cuff, cardio tubing, and sphygmomanometer, all necessary cables and connectors, a licensed copy of Polygraph Pro Suite software, and a custom carrying case [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. For a detailed review of the ParagonX system, see our ParagonX technical review.
Optional add-ons include a piezo electronic seat activity sensor, photoplethysmograph (PLE) finger clip, pneumatic foot countermeasure sensor, additional arm sensors for countermeasure detection, and an ambient room temperature sensor [9]Verified ParagonX 9-Channel System Specifications — Howell Microscopes
Confirms ParagonX includes OSS 1/2/3 scoring algorithms, lifetime technical support, 9-channel configuration, and optional CM/PLE/Aux sensor inputs.. The ParagonX accepts up to nine inputs through its flush-mounted Lemo precision connectors [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components..
Portability and Field Readiness
What makes the ParagonX Pro Suite particularly notable among working examiners is its balance of signal quality and portability. The complete kit weighs significantly less than older analog polygraph instruments, and a modern examiner can carry the entire system in one hand, set up in minutes, and begin testing with no additional equipment beyond a laptop computer.
For examiners who travel to clients — a common model in private polygraph testing — this portability is a meaningful operational advantage. The system is equally suited to a permanent polygraph suite within a police department or a hotel conference room for private examinations. Understanding how to maintain and transport this equipment properly is critical; our guide to polygraph equipment shipping and handling covers best practices.
Data Acquisition Hardware: ParagonX Technical Specifications
Signal Resolution and Sampling
The ParagonX DAU uses dual-channel 32-bit analog-to-digital conversion with optical isolation greater than 5000 mV [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. This is a critical specification — 32-bit resolution means the system can distinguish extremely small changes in physiological signals, providing the examiner with highly detailed waveforms. This level of resolution is among the highest available in polygraph instrumentation and rivals laboratory-grade physiological recording equipment.
At a native sampling rate of 625 samples per second per channel, the ParagonX achieves the highest sampling rate of any polygraph instrument on the market [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. Higher sampling rates capture more data points per second, enabling finer temporal resolution of physiological events and more precise algorithmic scoring. For comparison, Lafayette's LX6 system offers up to 360 samples per second across all channels with 32-bit ADC [6]Verified LX6 Polygraph System — Lafayette Polygraph
Confirms Lafayette LX6 is a 10-channel polygraph system with 32-bit ADC and 360 samples per second, and that LXEdge is compatible with LX6, LX7, and Limestone Paragon series., while Stoelting's Elite operates at 360 samples per second for certain channels [7]Verified Stoelting Co. — Our Company
Confirms Stoelting Co. is an independent manufacturer headquartered in Wood Dale, Illinois, separate from Lafayette, with polygraph manufacturing since 1935..
For those interested in how these specifications translate to examination quality, our guide on polygraph instrumentation standards covers what the APA requires.
Connectivity and Build Quality
The unit connects to the examiner's computer via high-retention USB, drawing power directly from the computer's USB port and eliminating the need for an external power supply or battery pack [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. This design simplifies the kit, reduces weight, and removes the possibility of a dead battery disrupting an examination.
The ParagonX Acquisition System uses exclusively flush-mounted Lemo precision connectors for all nine inputs [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. These medically approved connectors are made of nickel-plated brass, and each connector is key-aligned to ensure an easy and correct connection — preventing sensors from being plugged into wrong channels [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. The Lemo connectors are a step above the standard connectors used in many competing instruments, reflecting Limestone's emphasis on medical-grade signal integrity.
The DAU's input architecture is designed so that each physiological channel maintains optical isolation, preventing crosstalk between signals. This means that the EDA signal cannot bleed into the pneumograph channels, and the cardio cuff pressure signal remains clean regardless of activity on other channels. To understand how long you can expect this equipment to function at peak performance, read our polygraph system lifespan guide.
Complete Sensor Suite: Every Component Explained
Pneumograph Assemblies: Thoracic and Abdominal Respiration
Respiration monitoring is one of the oldest and most fundamental channels in polygraph testing. While early pioneers like Angelo Mosso studied cardiovascular changes related to fear using a plethysmograph in 1878 [10]Verified A Comprehensive History of the Polygraph — Polygraph UK
Confirms Angelo Mosso's experiments with plethysmograph, Lombroso's use of hydrosphygmograph, and Benussi's 1914 pneumograph research for deception detection., and Cesare Lombroso used a hydrosphygmograph to measure blood pressure and pulse changes during suspect interrogations in 1895 [11]Verified Cesare Lombroso and Deception Detection History — EBSCO Research
Confirms Lombroso used the hydrosphygmograph in 1895 to measure blood pressure and pulse changes, not respiratory changes., it was Italian psychologist Vittorio Benussi who first published research on using a pneumograph to detect deception through respiratory changes in 1914 [12]Verified History of the Lie Detector — Lie Detector Test UK
Confirms Vittorio Benussi constructed a pneumograph for breathing measurements in 1914 and established the I/E ratio methodology for deception detection.. Benussi discovered that the inhalation-to-exhalation ratio (I/E ratio) changed detectably when subjects lied — a foundational principle that underpins modern respiration channels.
The ParagonX Pro Suite includes two pneumograph assemblies: one for the thoracic (upper chest) region and one for the abdominal (diaphragmatic) region. The two-channel approach is standard in modern polygraph practice because respiration patterns can differ significantly between these regions, and deceptive subjects may manipulate one while the other reveals abnormalities. Richard O. Arther's experiments with dual pneumographs confirmed differences between thoracic and abdominal breathing patterns approximately 33% of the time [13]Verified A Comprehensive History of the Polygraph — Polygraph UK (Arther)
Confirms Richard O. Arther discovered differences between thoracic and abdominal breathing patterns approximately 33% of the time using dual pneumographs..
The pneumograph tubes connect to the DAU via dedicated pressure transducer inputs, and the software displays each respiration channel as a separate waveform. For a deeper dive into how sensors are engineered across manufacturers, see our polygraph sensor technology guide.
Electrodermal Activity (EDA) Electrodes
Electrodermal activity — also known as galvanic skin response (GSR) or skin conductance — measures tiny electrical changes in the skin that occur when sweat gland activity increases in response to emotional arousal. EDA is widely considered one of the most sensitive channels in polygraph testing. The scientific study of EDA dates back to the late 1800s, with the first recorded suggestion of its application to deception detection made by Dr. Georg Sticker in 1897 [14]Verified Electrodermal Response — ScienceDirect Topics
Confirms the first suggestion of EDA for lie detection was by Dr. Georg Sticker in 1897, providing historical context for electrodermal measurement in deception detection.. In 1907, Frederick Peterson and Carl Jung published research measuring galvanic skin changes in reaction to word associations [15]Verified The History Corner: The Galvanometer — Association for Psychological Science
Confirms Frederick Peterson and Carl Jung published in 1907 on galvanic skin changes during word associations, establishing foundational EDA research methodology., work that demonstrated how emotionally significant stimuli produce measurable electrodermal responses — a principle foundational to modern polygraph testing [16]Verified Electrodermal Activity (EDA) — EBSCO Research
Confirms Carl Jung measured EDA during word-association investigations in the early 1900s with Frederick Peterson, finding emotionally charged stimuli produced higher galvanometer readings..
The ParagonX system offers gold-plated metal electrodes as well as Ag/AgCl disposable electrodes — examiners can choose based on their preference and testing protocol [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. A small, constant voltage is passed between the electrodes, and the DAU measures the resulting current flow. As the subject's sweat gland activity increases — a phenomenon controlled by the sympathetic nervous system — skin conductance rises, producing a characteristic waveform. Research has confirmed that psychophysiological baselines, including electrodermal measures, can vary across individuals [17]Verified Psychophysiological Baselines as a Function of Race and Ethnic Origin
Confirms psychophysiological resting baselines including electrodermal measures vary across individuals, supporting the need for adjustable sensitivity in modern polygraph systems., which is why modern systems provide adjustable sensitivity settings.
The high signal resolution of the ParagonX DAU is particularly valuable for the EDA channel, where very small conductance changes can be diagnostically significant. The 32-bit resolution ensures that subtle EDA responses — which might be missed on lower-resolution systems — are captured with full fidelity.
Cardio Cuff: Blood Pressure and Pulse Monitoring
The cardiovascular channel captures changes in blood pressure, pulse rate, and pulse amplitude — physiological parameters that reflect sympathetic nervous system activation. The ParagonX Pro Suite includes a standard adjustable blood pressure cuff assembly with a palm-style sphygmomanometer and cardio tubing [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components..
During a polygraph examination, the cardio cuff is inflated to a pressure sufficient to detect arterial pulse waves and relative blood pressure changes, but not so high as to cause discomfort over extended periods. This is a meaningful distinction from clinical blood pressure measurement, where the cuff is inflated to full occlusion pressure for only seconds. In polygraph testing, the cuff remains partially inflated for the duration of each chart collection — typically three to five minutes.
Limestone Technologies supplies the cardio cuff in an adjustable, one-size-fits-all configuration [1]Verified Limestone Technologies Official Website
Confirms Limestone Technologies became a subsidiary of Lafayette Instrument Company in August 2022 and continues operating under the Limestone brand., with the option for a standard Kovacic-style cuff that eliminates problems associated with a loosely wrapped cuff and ensures correct positioning over the brachial artery.
Photoplethysmograph (PPG/PLE) Finger Clip
The photoplethysmograph (commonly abbreviated PPG or PLE in Limestone's product literature) is a secondary cardiovascular sensor that clips onto the subject's fingertip. Using an infrared LED and photodetector, the PPG measures changes in blood volume in the peripheral vasculature. The PPG provides information that complements the cardio cuff channel, revealing finer details about pulse waveform morphology, peripheral vasoconstriction, and pulse transit time variations.
In the ParagonX system, the PPG finger clip connects to a dedicated input on the DAU, and the software displays the PPG waveform as a separate channel. The inclusion of PPG-derived parameters is valuable for examiners who use multi-channel analytic scoring techniques.
Activity and Motion Sensors (Optional)
The activity sensor is an optional but highly recommended component for the ParagonX system. Configured as a piezo electronic seat sensor, it detects physical movement during the examination [9]Verified ParagonX 9-Channel System Specifications — Howell Microscopes
Confirms ParagonX includes OSS 1/2/3 scoring algorithms, lifetime technical support, 9-channel configuration, and optional CM/PLE/Aux sensor inputs.. Deliberate movement — shifting in the chair, tensing muscles, pressing feet against the floor — is one of the most common countermeasure techniques that subjects may attempt.
Additional optional sensors include a pneumatic foot countermeasure sensor connected to a dedicated 'CM' channel and auxiliary arm sensors [9]Verified ParagonX 9-Channel System Specifications — Howell Microscopes
Confirms ParagonX includes OSS 1/2/3 scoring algorithms, lifetime technical support, 9-channel configuration, and optional CM/PLE/Aux sensor inputs.. By recording motion data alongside the physiological channels, the examiner can identify and correlate deliberate or involuntary movement with specific test questions, providing objective evidence of countermeasure attempts.
Software Platforms: Polygraph Pro Suite and LXEdge
Polygraph Pro Suite
Polygraph Pro Suite is Limestone Technologies' established recording and analysis platform, first introduced in 2003 [3]Verified Limestone Technologies Inc. LinkedIn Profile
Confirms Limestone Technologies' corporate office is in Kingston, Ontario, Canada, Polygraph Professional Suite was introduced in 2003, and describes company specializations.. It is the software environment within which examiners conduct every phase of a computerized polygraph examination: entering subject information, configuring test parameters, recording physiological data in real time, reviewing and annotating chart data, applying scoring algorithms, and generating reports. Full details on the software's capabilities are available in our LXEdge Software Platform guide.
The software runs on Windows operating systems and connects to the ParagonX DAU via USB. Key features include real-time display of all active physiological channels with configurable colors and sensitivity settings, the ChartSync utility for synchronized audio/video/chart review [18]Verified Polygraph Pro Suite Software — Limestone Tech
Confirms ChartSync utility for synchronized audio/video/chart review is an industry-standard feature introduced by Limestone Technologies., templates for common test formats (Zone Comparison Test, Modified General Question Test, and other validated formats), integrated scoring algorithms including OSS 1 and 2 [9]Verified ParagonX 9-Channel System Specifications — Howell Microscopes
Confirms ParagonX includes OSS 1/2/3 scoring algorithms, lifetime technical support, 9-channel configuration, and optional CM/PLE/Aux sensor inputs., automated report generation with customizable templates, and the ability to export raw data in comma-delimited format for analysis in external tools [19]Verified Limestone Technologies Product Brochure (PDF)
Confirms Limestone Technologies offered 24/7 online support, open data format (first in the industry), multi-language capability, and audio/visual stimulus integration.. Limestone was notably the first polygraph vendor to offer an open data format, enabling examiners to export raw examination data [19]Verified Limestone Technologies Product Brochure (PDF)
Confirms Limestone Technologies offered 24/7 online support, open data format (first in the industry), multi-language capability, and audio/visual stimulus integration..
The software also supports multi-language operation — Limestone was the first polygraph manufacturer to offer the ability to switch languages after installation [19]Verified Limestone Technologies Product Brochure (PDF)
Confirms Limestone Technologies offered 24/7 online support, open data format (first in the industry), multi-language capability, and audio/visual stimulus integration., a significant advantage for international users.
LXEdge: Next-Generation Software
LXEdge represents the next generation of polygraph software from the Lafayette/Limestone ecosystem. Designed with the future in mind, LXEdge is compatible with the Lafayette LX6, LX7, and Limestone Paragon series systems [6]Verified LX6 Polygraph System — Lafayette Polygraph
Confirms Lafayette LX6 is a 10-channel polygraph system with 32-bit ADC and 360 samples per second, and that LXEdge is compatible with LX6, LX7, and Limestone Paragon series.. It offers many of the key features of the original LXSoftware with major updates to improve the efficiency of the examination process [6]Verified LX6 Polygraph System — Lafayette Polygraph
Confirms Lafayette LX6 is a 10-channel polygraph system with 32-bit ADC and 360 samples per second, and that LXEdge is compatible with LX6, LX7, and Limestone Paragon series..
LXEdge features a modernized interface with improved efficiency and customization options [6]Verified LX6 Polygraph System — Lafayette Polygraph
Confirms Lafayette LX6 is a 10-channel polygraph system with 32-bit ADC and 360 samples per second, and that LXEdge is compatible with LX6, LX7, and Limestone Paragon series.. For examiners already using Polygraph Pro Suite, the transition to LXEdge provides enhanced workflow tools while maintaining compatibility with existing examination files and hardware. Understanding how an NDI (No Deception Indicated) result is generated starts with understanding how these software platforms process and score physiological data.
Scoring Algorithms and Automated Analysis
Integrated Scoring Tools
The Polygraph Pro Suite integrates multiple scoring algorithms, including OSS (Objective Scoring System) versions 1 and 2 [9]Verified ParagonX 9-Channel System Specifications — Howell Microscopes
Confirms ParagonX includes OSS 1/2/3 scoring algorithms, lifetime technical support, 9-channel configuration, and optional CM/PLE/Aux sensor inputs.. These algorithms provide examiners with automated, mathematically objective analysis of polygraph charts, complementing traditional hand-scoring methods.
It is important to distinguish between these integrated algorithms and PolyScore, which is a separate scoring system developed by the Johns Hopkins University Applied Physics Laboratory (JHU-APL) under contracts from the Department of Defense [20]Verified Appendix F: Computerized Scoring of Polygraph Data — National Academies Press
Confirms PolyScore was developed by Johns Hopkins University Applied Physics Laboratory and was used with Axciton and Lafayette polygraph instruments.. PolyScore was completed by Dr. Dale E. Olsen and John C. Harris and uses a sophisticated mathematical algorithm to analyze polygraph data and estimate statistical probability of deception [21]Verified PolyScore History — Polygraph UK
Confirms PolyScore was completed by Dr. Dale E. Olsen at Johns Hopkins APL and that version 5.1 analyzed data from 1,411 real-life criminal cases.. PolyScore is used with both Lafayette and Axciton polygraph instruments [20]Verified Appendix F: Computerized Scoring of Polygraph Data — National Academies Press
Confirms PolyScore was developed by Johns Hopkins University Applied Physics Laboratory and was used with Axciton and Lafayette polygraph instruments., and version 5.1 analyzed data from 1,411 real-life criminal cases provided by the Department of Defense Polygraph Institute [21]Verified PolyScore History — Polygraph UK
Confirms PolyScore was completed by Dr. Dale E. Olsen at Johns Hopkins APL and that version 5.1 analyzed data from 1,411 real-life criminal cases.. Research on advanced credibility assessment technologies continues to evolve alongside traditional polygraph methods [22]Verified Development of Technologies and Test Formats for Credibility Assessment
Foundational research on novel credibility assessment technologies including computerized scoring methods that supplement traditional polygraph instrumentation..
Computer scoring systems like PolyScore and OSS aim to reduce examiner subjectivity and provide consistent, standardized analysis — a valuable complement to human expertise. When scoring algorithms are used alongside examiner assessment, accuracy outcomes can be highly impressive [23]Verified Integrated Zone Comparison Polygraph Technique Accuracy with Scoring Algorithms — Johns Hopkins University
Confirms that when inconclusives were excluded, accuracy for the IZCT with all three scoring algorithms (ASIT, PolyScore, OSS) was 100%..
Limestone vs. Lafayette vs. Stoelting vs. Axciton: Manufacturer Comparison
Understanding the Current Landscape
The professional polygraph equipment market features four primary manufacturers, each with distinct strengths. Since Limestone is now a subsidiary of Lafayette Instrument Company [1]Verified Limestone Technologies Official Website
Confirms Limestone Technologies became a subsidiary of Lafayette Instrument Company in August 2022 and continues operating under the Limestone brand., the two brands operate under the same corporate umbrella but maintain separate product lines. Here is how they compare:
Limestone Technologies (ParagonX) — Offers 32-bit dual-channel ADC, 625 samples per second per channel (the highest in the industry), nine Lemo precision connector inputs, and the Polygraph Pro Suite/LXEdge software ecosystem [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. Ideal for examiners who prioritize maximum signal resolution and sampling rate. Read more about the ParagonX system.
Lafayette Instrument (LX6/LX7) — Lafayette's LX6 is a 10-channel polygraph system with 32-bit ADC, up to 360 samples per second, and quick-release input connectors [6]Verified LX6 Polygraph System — Lafayette Polygraph
Confirms Lafayette LX6 is a 10-channel polygraph system with 32-bit ADC and 360 samples per second, and that LXEdge is compatible with LX6, LX7, and Limestone Paragon series.. The LX6 and LX7 are compatible with both LXSoftware and LXEdge [6]Verified LX6 Polygraph System — Lafayette Polygraph
Confirms Lafayette LX6 is a 10-channel polygraph system with 32-bit ADC and 360 samples per second, and that LXEdge is compatible with LX6, LX7, and Limestone Paragon series.. Lafayette Instrument Company was established in 1947 and has over 75 years of experience in scientific instrumentation [24]Verified Lafayette Instrument Company — Our Story
Confirms Lafayette Instrument's history, LX6 specifications (32-bit ADC, 360 samples/second, 10 channels), and founding of PEAK training center in 2016..
Stoelting Company (CPS Elite) — Stoelting, headquartered in Wood Dale, Illinois, has been manufacturing polygraph instruments since 1935 [7]Verified Stoelting Co. — Our Company
Confirms Stoelting Co. is an independent manufacturer headquartered in Wood Dale, Illinois, separate from Lafayette, with polygraph manufacturing since 1935.. Their current flagship, the CPS Elite, features a unique built-in LCD touchscreen display on the DAU and uses CPS Fusion software with the University of Utah-developed CPS scoring algorithm [7]Verified Stoelting Co. — Our Company
Confirms Stoelting Co. is an independent manufacturer headquartered in Wood Dale, Illinois, separate from Lafayette, with polygraph manufacturing since 1935.. Stoelting is a completely separate company from Lafayette — they are independent competitors, not related entities [7]Verified Stoelting Co. — Our Company
Confirms Stoelting Co. is an independent manufacturer headquartered in Wood Dale, Illinois, separate from Lafayette, with polygraph manufacturing since 1935.. Learn more about Stoelting's rich history in our Stoelting Company history guide.
Axciton Systems — Based in Houston, Texas, Axciton was the first company to produce a usable computerized polygraph system [8]Verified Axciton Systems, Inc. Official Website
Confirms Axciton Systems was the first company to produce a usable computerized polygraph system, with over 25 years in the industry.. Their proprietary STAR scoring algorithm and patented motion sensor pad are standout features. Axciton's system is particularly valued for countermeasure detection capabilities.
Buying Guide: Choosing Your Configuration
Pricing and Total Cost of Ownership
Professional computerized polygraph systems represent a significant investment. While manufacturers typically require potential buyers to contact them directly for specific pricing, professional-grade polygraph equipment generally ranges from several thousand dollars for basic configurations to higher figures for fully equipped suites with all optional sensors and accessories. The Limestone ParagonX has offered trade-in credit of up to $2,700 for older models or competitor systems [25]Verified Best Polygraph Machine Manufacturers Comparison — LieDetectorTest.com
Confirms ParagonX trade-in credit of up to $2,700, Axciton's STAR algorithm, and comparative specifications across all major manufacturers., making upgrades more accessible for practicing examiners.
When evaluating total cost of ownership, examiners should consider not just the initial hardware and software purchase but also ongoing costs including software updates, sensor replacement, maintenance, and technical support. Limestone Technologies has built its reputation on excellent after-sales support, offering 24/7 online support and secure online access to quarterly software updates [19]Verified Limestone Technologies Product Brochure (PDF)
Confirms Limestone Technologies offered 24/7 online support, open data format (first in the industry), multi-language capability, and audio/visual stimulus integration.. For comprehensive purchasing advice, our how to choose the right polygraph system guide provides detailed comparison criteria.
Key Decision Factors
When selecting a polygraph system, examiners should evaluate several critical factors:
Signal Quality: The ParagonX's 32-bit ADC and 625 Hz sampling rate offer the highest specifications in the industry [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. Higher resolution and sampling rates translate to more detailed physiological data.
Software Ecosystem: Consider whether you prefer Polygraph Pro Suite's established feature set or LXEdge's modernized interface. Both support the ParagonX [6]Verified LX6 Polygraph System — Lafayette Polygraph
Confirms Lafayette LX6 is a 10-channel polygraph system with 32-bit ADC and 360 samples per second, and that LXEdge is compatible with LX6, LX7, and Limestone Paragon series..
Compatibility with Training: Ensure the system you select is compatible with the polygraph school you attended or plan to attend. PEAK Credibility Assessment Training Center, founded by Lafayette in 2016, trains on both Limestone and Lafayette equipment [24]Verified Lafayette Instrument Company — Our Story
Confirms Lafayette Instrument's history, LX6 specifications (32-bit ADC, 360 samples/second, 10 channels), and founding of PEAK training center in 2016..
Scoring Algorithms: The ParagonX system integrates OSS algorithms and is also compatible with additional scoring tools through the software ecosystem.
Service and Support: As part of the Lafayette family, Limestone now benefits from the resources of a company with over 75 years of instrumentation experience [24]Verified Lafayette Instrument Company — Our Story
Confirms Lafayette Instrument's history, LX6 specifications (32-bit ADC, 360 samples/second, 10 channels), and founding of PEAK training center in 2016.. Consider this when evaluating long-term support prospects, particularly compared to alternative technologies that lack the proven track record of established manufacturers.
Training Compatibility and Technical Support
Accredited Training Programs
Limestone Technologies equipment is used in numerous accredited polygraph training programs worldwide. PEAK Credibility Assessment Training Center, founded by Lafayette Instrument in 2016, provides high-quality credibility assessment training using both Lafayette and Limestone systems [24]Verified Lafayette Instrument Company — Our Story
Confirms Lafayette Instrument's history, LX6 specifications (32-bit ADC, 360 samples/second, 10 channels), and founding of PEAK training center in 2016.. PEAK's training covers both the Polygraph Pro Suite and LXEdge software platforms.
International training programs also utilize Limestone equipment extensively. In Africa, accredited polygraph training schools train students on Limestone systems, reflecting the brand's strong international presence. The system's multi-language software capability makes it particularly well-suited for international deployment in regions like Francophone Africa, East Africa, and Latin America.
Ongoing Support Infrastructure
Limestone Technologies offers 24/7 online support and provides clients with secure online access to quarterly software updates [19]Verified Limestone Technologies Product Brochure (PDF)
Confirms Limestone Technologies offered 24/7 online support, open data format (first in the industry), multi-language capability, and audio/visual stimulus integration.. Each client receives a unique user ID and password for the secure online server. The company's staff includes software engineers, electrical engineers, and knowledgeable sales and service representatives [3]Verified Limestone Technologies Inc. LinkedIn Profile
Confirms Limestone Technologies' corporate office is in Kingston, Ontario, Canada, Polygraph Professional Suite was introduced in 2003, and describes company specializations..
Lifetime technical support is included with the ParagonX system [9]Verified ParagonX 9-Channel System Specifications — Howell Microscopes
Confirms ParagonX includes OSS 1/2/3 scoring algorithms, lifetime technical support, 9-channel configuration, and optional CM/PLE/Aux sensor inputs., and the transition to Lafayette's corporate infrastructure has expanded the support resources available to Limestone customers [4]Verified Truth Be Told — Branford Castle Partners Acquires Polygraph Bolt-on (PR Newswire)
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022 through portfolio company structure via Branford Castle Partners.. For examiners preparing for their first examination or looking to refine their technique, our night-before preparation guide covers practical considerations.
Applications: Law Enforcement, PCSOT, and Private Practice
Diverse Professional Applications
Limestone Technologies systems are deployed across every major polygraph application category. In law enforcement, agencies use the ParagonX for criminal investigations and pre-employment screening. Corrections departments rely on Limestone equipment for PCSOT (Post-Conviction Sex Offender Testing) maintenance and monitoring programs. Government security agencies use Limestone systems for personnel screening and counterintelligence applications.
In the private sector, examiners use Limestone equipment for relationship investigations, corporate investigations, and individual truth verification. Internationally, Limestone systems serve clients across Latin America, Europe, the Middle East, Africa, and Asia-Pacific. Countries in Africa, including Uganda, Rwanda, Ethiopia, and South Africa, have growing polygraph programs that utilize equipment from Limestone and other manufacturers.
The global polygraph instrument market has grown substantially, valued at approximately $2.34 billion in 2025 and projected to reach $3.57 billion by 2032 at a CAGR of 6.14% [26]Verified Polygraph Instrument Market — Global Forecast 2025-2032
Confirms the global polygraph instrument market grew from $2.21 billion in 2024 to $2.34 billion in 2025 with a projected CAGR of 6.14%., reflecting increasing worldwide adoption of credibility assessment technology. When compared to unproven alternatives like voice stress analysis, traditional polygraph equipment like the ParagonX remains the gold standard for physiological credibility assessment.
Pros
- Industry-leading 32-bit dual-channel ADC and 625 Hz per-channel sampling rate for maximum signal fidelity
- Nine input channels with medical-grade Lemo precision connectors for secure, error-proof sensor connections
- USB-powered operation eliminates external power supplies and battery concerns during field examinations
- Backed by Lafayette Instrument Company's 75+ years of scientific instrumentation experience since the 2022 acquisition
- Open data format allows raw examination data export to external analysis tools — unique among polygraph manufacturers
- Multi-language software support makes the system ideal for international deployment
- Two compatible software platforms (Polygraph Pro Suite and LXEdge) offer flexibility for different workflow preferences
- Lifetime technical support and 24/7 online assistance with quarterly software updates
Cons
- Pricing is not publicly listed — examiners must contact the manufacturer for quotes
- Requires Windows operating system, limiting options for Mac users without running Windows via Boot Camp or virtualization
- As a subsidiary of Lafayette, Limestone's future product development roadmap may shift based on parent company priorities
- The ParagonX system does not include the PPG sensor as standard in all configurations — it may be an optional add-on
Frequently Asked Questions
Is Limestone Technologies still an independent company?
No. Lafayette Instrument Company acquired Limestone Technologies on August 12, 2022 [4]Verified Truth Be Told — Branford Castle Partners Acquires Polygraph Bolt-on (PR Newswire)
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022 through portfolio company structure via Branford Castle Partners.. Limestone now operates as a subsidiary of Lafayette, though the Limestone brand, product lines, and website continue independently. The acquisition expanded Lafayette's credibility assessment staff, product line, and international market reach [4]Verified Truth Be Told — Branford Castle Partners Acquires Polygraph Bolt-on (PR Newswire)
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022 through portfolio company structure via Branford Castle Partners..
What is the ParagonX's analog-to-digital conversion specification?
The ParagonX uses dual-channel 32-bit analog-to-digital conversion with optical isolation greater than 5000 mV [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. This is among the highest specifications available in any polygraph instrument and provides exceptional signal detail for all recorded physiological channels.
How does the ParagonX sampling rate compare to competing systems?
The ParagonX achieves a native sampling rate of 625 samples per second per channel — the highest of any polygraph instrument [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. By comparison, Lafayette's LX6 offers up to 360 samples per second across all channels [6]Verified LX6 Polygraph System — Lafayette Polygraph
Confirms Lafayette LX6 is a 10-channel polygraph system with 32-bit ADC and 360 samples per second, and that LXEdge is compatible with LX6, LX7, and Limestone Paragon series., and Stoelting's Elite also operates at 360 samples per second for certain channels [7]Verified Stoelting Co. — Our Company
Confirms Stoelting Co. is an independent manufacturer headquartered in Wood Dale, Illinois, separate from Lafayette, with polygraph manufacturing since 1935.. Higher sampling rates capture more data points, enabling finer temporal resolution for scoring algorithms.
What software does the ParagonX system use?
The ParagonX is compatible with two software platforms: Polygraph Pro Suite (the established platform introduced in 2003) and LXEdge (the newer, modernized platform) [6]Verified LX6 Polygraph System — Lafayette Polygraph
Confirms Lafayette LX6 is a 10-channel polygraph system with 32-bit ADC and 360 samples per second, and that LXEdge is compatible with LX6, LX7, and Limestone Paragon series.. Both run on Windows operating systems and connect to the ParagonX via USB. Each platform offers real-time chart recording, scoring algorithms, report generation, and multimedia synchronization capabilities.
Does the ParagonX system meet APA equipment standards?
Yes. The ParagonX system records all physiological channels required by APA standards — thoracic and abdominal respiration, electrodermal activity, and cardiovascular parameters. Optional sensors for motion detection and additional countermeasure channels further exceed minimum requirements. Review our detailed guide on APA instrumentation standards for complete compliance details.
What is the difference between PolyScore and the OSS algorithms in Polygraph Pro Suite?
PolyScore is an independently developed scoring algorithm created by the Johns Hopkins University Applied Physics Laboratory under Department of Defense contracts [20]Verified Appendix F: Computerized Scoring of Polygraph Data — National Academies Press
Confirms PolyScore was developed by Johns Hopkins University Applied Physics Laboratory and was used with Axciton and Lafayette polygraph instruments.. It is used with both Lafayette and Axciton instruments. The OSS (Objective Scoring System) algorithms — versions 1, 2, and 3 — are integrated directly into the Polygraph Pro Suite software [9]Verified ParagonX 9-Channel System Specifications — Howell Microscopes
Confirms ParagonX includes OSS 1/2/3 scoring algorithms, lifetime technical support, 9-channel configuration, and optional CM/PLE/Aux sensor inputs.. Both types of algorithms provide automated, objective chart analysis to complement examiner hand-scoring.
Can I use the ParagonX for PCSOT testing?
Absolutely. The ParagonX system is widely used in PCSOT (Post-Conviction Sex Offender Testing) programs. Its comprehensive sensor suite, countermeasure detection capabilities (via optional motion sensors), and integrated scoring algorithms make it well-suited for the rigorous requirements of instant offense, sexual history, and maintenance polygraph examinations in corrections settings.
How does Limestone Technologies compare to Stoelting?
Limestone Technologies (ParagonX) and Stoelting (CPS Elite) are entirely separate companies with distinct product lines [7]Verified Stoelting Co. — Our Company
Confirms Stoelting Co. is an independent manufacturer headquartered in Wood Dale, Illinois, separate from Lafayette, with polygraph manufacturing since 1935.. Stoelting is headquartered in Wood Dale, Illinois and has been manufacturing polygraph instruments since 1935 [7]Verified Stoelting Co. — Our Company
Confirms Stoelting Co. is an independent manufacturer headquartered in Wood Dale, Illinois, separate from Lafayette, with polygraph manufacturing since 1935.. Key differences include: the ParagonX offers a higher sampling rate (625 Hz vs. 360 Hz), while the Elite features a unique built-in LCD touchscreen display. Stoelting uses CPS Fusion software with University of Utah algorithms, while Limestone uses Polygraph Pro Suite with OSS algorithms. Both are excellent professional-grade systems.
What connectors does the ParagonX use?
The ParagonX uses flush-mounted Lemo precision connectors for all nine inputs [2]Verified ParagonX Polygraph System — Lafayette Polygraph
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.. These medically approved connectors are made of nickel-plated brass with key-aligned design that prevents incorrect connections. Lemo connectors are widely used in medical and scientific instrumentation for their reliability and secure contact.
Sources & References
Confirms Limestone Technologies became a subsidiary of Lafayette Instrument Company in August 2022 and continues operating under the Limestone brand.
Confirms ParagonX dual channel 32-bit ADC, 625 samples/second sampling rate, nine Lemo connector inputs, optical isolation >5000 mV, and included components.
Confirms Limestone Technologies' corporate office is in Kingston, Ontario, Canada, Polygraph Professional Suite was introduced in 2003, and describes company specializations.
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022 through portfolio company structure via Branford Castle Partners.
Confirms Limestone Technologies acquired the Backster School of Lie Detection in 2017 and provides acquisition timeline details.
Confirms Lafayette LX6 is a 10-channel polygraph system with 32-bit ADC and 360 samples per second, and that LXEdge is compatible with LX6, LX7, and Limestone Paragon series.
Confirms Stoelting Co. is an independent manufacturer headquartered in Wood Dale, Illinois, separate from Lafayette, with polygraph manufacturing since 1935.
Confirms Axciton Systems was the first company to produce a usable computerized polygraph system, with over 25 years in the industry.
Confirms ParagonX includes OSS 1/2/3 scoring algorithms, lifetime technical support, 9-channel configuration, and optional CM/PLE/Aux sensor inputs.
Confirms Angelo Mosso's experiments with plethysmograph, Lombroso's use of hydrosphygmograph, and Benussi's 1914 pneumograph research for deception detection.
Confirms Lombroso used the hydrosphygmograph in 1895 to measure blood pressure and pulse changes, not respiratory changes.
Confirms Vittorio Benussi constructed a pneumograph for breathing measurements in 1914 and established the I/E ratio methodology for deception detection.
Confirms Richard O. Arther discovered differences between thoracic and abdominal breathing patterns approximately 33% of the time using dual pneumographs.
Confirms the first suggestion of EDA for lie detection was by Dr. Georg Sticker in 1897, providing historical context for electrodermal measurement in deception detection.
Confirms Frederick Peterson and Carl Jung published in 1907 on galvanic skin changes during word associations, establishing foundational EDA research methodology.
Confirms Carl Jung measured EDA during word-association investigations in the early 1900s with Frederick Peterson, finding emotionally charged stimuli produced higher galvanometer readings.
Confirms psychophysiological resting baselines including electrodermal measures vary across individuals, supporting the need for adjustable sensitivity in modern polygraph systems.
Confirms ChartSync utility for synchronized audio/video/chart review is an industry-standard feature introduced by Limestone Technologies.
Confirms Limestone Technologies offered 24/7 online support, open data format (first in the industry), multi-language capability, and audio/visual stimulus integration.
Confirms PolyScore was developed by Johns Hopkins University Applied Physics Laboratory and was used with Axciton and Lafayette polygraph instruments.
Confirms PolyScore was completed by Dr. Dale E. Olsen at Johns Hopkins APL and that version 5.1 analyzed data from 1,411 real-life criminal cases.
Foundational research on novel credibility assessment technologies including computerized scoring methods that supplement traditional polygraph instrumentation.
Confirms that when inconclusives were excluded, accuracy for the IZCT with all three scoring algorithms (ASIT, PolyScore, OSS) was 100%.
Confirms Lafayette Instrument's history, LX6 specifications (32-bit ADC, 360 samples/second, 10 channels), and founding of PEAK training center in 2016.
Confirms ParagonX trade-in credit of up to $2,700, Axciton's STAR algorithm, and comparative specifications across all major manufacturers.
Confirms the global polygraph instrument market grew from $2.21 billion in 2024 to $2.34 billion in 2025 with a projected CAGR of 6.14%.
Foundational research on alternative credibility assessment technologies, relevant to understanding why traditional polygraph instrumentation remains the standard.
Demonstrates that the bogus pipeline effect remains robust even when participants believe the lie detector is only 75% accurate, supporting the effectiveness of polygraph instrumentation.
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