VCC Glossary

Status Indicator Glossary

The Ultimate Status Indicator Glossary

Core Capabilities

There’s a lot of lingo in the world of light pipes, PMIs and status indication. So we created your go-to glossary for all things indicator. 

Feel free to bookmark this page and check back often, as new definitions are continually being added.

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Acrylic Light Pipes

Typically made of PMMA (polymethylmethacrylate), acrylic light pipes are the preferred solution for a range of status indication applications. These optical-grade light pipes provide superior light transmission compared to other light pipe materials. 

They’re also much more cost-effective, can withstand UV’s damaging rays and operate in temperatures ranging from 80-110°C.



A bezel is a ring that encases the LED in order to hold the lens in place or connect the lamp to the housing. This element provides a secure, mechanical fit that can provide protection from moisture and dust. The material used for a bezel can be plastic, stainless steel, nickel or other types. Bezels can also be used to change the aesthetic of a design.

Depending on the design, a bezel can be flush with the panel, prominent or even recessed.

types of panel mount indicator bezel




A bi-color LED is one that can change from one color to another within the same LED / status indicator.  Red/green or Red/yellow are common bi-color combinations. VCC can also customize a color combination to accommodate any visual language.
red green bi-color led



AKA: Bipin, bipin cap, bipin socket, two-pin

A bi-pin is a type of lamp fitting that uses two pins to connect the bulb to the device. This lamp fitting is commonly used in lighting technologies including LED, incandescent, halogen, neon and fluorescent.

Board-Mount Light Pipes

Like the name implies, board mount light pipes are affixed to the PCB of the device, as opposed to attaching to the control panel or HMI. 

In some instances, a board-mount light pipe may also attach to the HMI for added security, such as the VBL Series.

In addition to providing design flexibility, board-mount light pipes can also protect components from electrostatic discharge (ESD).

lpcm series light pipe on pcb with smd led


AKA: Full Brightness

The brightness of any type of led, indicator or lamp is measured in lumens. The higher the lumens, the brighter the light. Unlike other lighting technologies, an LED can achieve full brightness in milliseconds.
vcc ip61 a21 emergency led bulb incandescent

Bulk Scatter Material

AKA: Bulk Scattering Fillers

Bulk scatter is a technique used to diffuse light throughout a light pipe and create better uniformity by applying bulk scatter materials, such as treated powders to the light pipe. These materials can help reduce hotspots.


Cable Crimping

When using connectors instead of soldering electronic components to the device, the cables must be crimped where the bare cable is terminated inside the connector. 
This process can save a step in production when it’s handled by the manufacturer of the indicator. Learn more here.

cable connector with cable crimp

Cable Cutting

Before a connector can be used, the bare wire just be sized appropriately and stripped at the connection point. OEMs like VCC offer cable cutting and crimping as value-add services that increase production and assembly.

Capacitive Touch

AKA: Capacitive Touch Sensor Displays, Cap Touch

Capacitive touch combines touch-sensing and display technology to provide a more intuitive experience for end-users. For example, VCC’s CSM Series uses surface mount (SMD) technology to mount LED sensor displays to the HMI. These cap touch sensors can be solid colors or include an icon overlay. By combining icons and colors, operator reaction times are increased.

CSM Series surface mount capacitive touch LED sensor



CE Mark

A product labeled with the CE mark indicates it meets all safety, health and environmental standards and laws required for sale within Europe.

CE Certification


AKA: Electronics Chassis, Electronics Enclosure

A chassis is an enclosure that helps protect the sensitive, yet critical electronic elements of a device. A variety of materials can be used to make the chassis, including stainless steel, plastic, aluminum and polycarbonate. Working conditions and exposure to moisture and dust should be determining factors when selecting a chassis material.

Color - Light Pipe Color

Light pipes are usually clear or white, yet the color used can help determine the visual language of a device, which makes it easier (or harder) for the end-user during operation. 

Some colors help carry more of the light from Point A to Point B. Others help focus the light so it doesn’t bleed into a different color on the control panel and cause confusion. Common color options are red, yellow, blue, and orange.

Whether the light pipe is made of polycarbonate or acrylic, the color can be customized.


Panel mount indicators can be connected by soldering the components to a device, or by using modular wire-to-wire connectors to establish a secure connection. Connectors help speed up production and assembly by making the process more efficient. There are several types of connectors that can be added as part of the PMI production process, including:

  • 2-position 
  • Crimp housing connector
  • Micro-fit connector
  • Micro rectangular power connector
  • Wire-to-wire crimp housing

panel mount indicator connectors

Control Panel

See also: Human-Machine Interface

A control panel is the interface on a device where the operator can monitor status, and in some cases, use buttons or knobs to operate the machine. 
There are many design and development techniques that can improve the communication between operator and machine. Learn more here.

human machine interface examples

Crimp Housing Connector

AKA: Crimp Connector Housings 

Crimp housing connectors are used to create solderless connections between terminated wires. The stripped wire is inserted into the connector, then “crimped” to provide a mechanically sound bond. 

Learn more about VCC’s connector solutions here.

cclb series custom connector on wires

Critical Angle

The critical angle is the angle of incidence or limiting angle that creates refraction. Depending on the medium used for the light pipe, the critical angle will vary. Exact calculations are required for the best outcomes, utilizing total internal reflection (TIR) to help the maximum amount of light reach the desired exit point.

light pipe design refraction

Learn more about the critical angle’s crucial role in light pipe performance in this blog post.

CSA Mark

Similar to the CE mark in Europe, the CSA mark on a product indicates it has met the safety and testing requirements of the Canadian Standard Association Group, which includes standards written or administered by the American National Standards Institute (ANSI), Underwriter Laboratories (UL), CSA Group (CSA), NSF International (NSF), and other North American and global organizations.
CSA logo

cULus Mark

A CULus mark ensures products that have met safety and all UL standards and requirements for Canada and the United States.

cULus Logo

Custom Light Pipe

Every device is different — from the footprint inside it to the operating conditions and optical properties required.

While VCC offers thousands of standard light pipes, sometimes a customized solution is the ideal one for the job at hand.

Whether it’s a light engine or a light pipe, customizing can help reduce costs in the long run by delivering the viewing angle, color, length, and brightness for the specific use.

Custom light pipe design can range from $500 to $5,000 (not including tooling costs), depending on the complexity.

Complex: Read Case Study
non surgical medical device

Custom PMI

A custom PMI is one that is either designed from the ground up using customer specifications or requirements, or the modification of an existing panel mount indicator. 

VCC can create a new PMI design or customize its thousands of standard products by changing the color, wattage, length of leads, lens options and IP rating. You can build your own PMI here.


Daylight Visibility

Daylight visibility is crucial in devices used outdoors where the sun’s glare could impact how well the end-user interprets the status indicator. 

The face or lens can impact a device’s daylight visibility. Look for devices that can achieve full brightness in milliseconds, even in daylight viewing conditions.

Dome Face

Light pipes are available with different tops or faces on the end where the light shines through the indicator or HMI, each their own unique advantages.

The dome face provides the widest viewing angle of all face shapes, making it a great fit for visibility where operators need to see the indicator from different perspectives, such as bending down or from the side

dome face light pipe


ESD Protection

Electrostatic discharge, or ESD, can cause surges in electricity that will damage a device. Even static can produce ESD with the power to do harm. Depending on the design of the device, protection from ESD can be achieved.

For example, board-mounted light pipes provide a base level of ESD protection because they are attached at the board rather than at the surface of the HMI, where static typically would occur.

Smart Parking Meter with Built-in ESD Protection. Read case study.



Also Known As – Exit Face or Exit Surface

See also: What is the exit face of a light pipe?

The face of the light pipe is where the light shines through an indicator. At the opposite end of the light pipe, you’ll find the LED or light source. 

The shape of the lens or face can impact how well the light travels from the light source to the exit surface.

Flat Face

When a light pipe has a flat face, its exit surface does not include a dome or semi-dome shape. Instead, the face is flush with the panel, which can provide a sleek, modern design.

When the light needs to travel a longer distance from the PCB or hot spots are a concern, a flat face can provide superior performance. The flat design focuses the light while delivering a 160-degree viewing angle.
flat face light pipe

Flammability Rating

See also: V-0 Vertical Burn Flammability Rating, V-1 Vertical Burn Flammability Rating, V-2 Vertical Burn Flammability Rating

The flammability rating is used to calculate the UL94V-0 flammability standard, the industry standard for the safety of our products.

To determine the flammability rating, UL (formerly Underwriter Laboratories) conducts a series of vertical and horizontal tests. A flame is held to a component for a specified amount of time, then UL assesses how the product reacts to the applications and gives it a rating from V-0 to V-2.

Flexible Light Pipe

See also: What is a flexible light pipe?

Light pipes typically fall into two main categories: flexible or rigid.

Flexible light pipes are made to bend and move to carry light around corners and even sharp angles. They’re also helpful when light needs to travel longer distances from the PCB or light source to the panel.

Flexible light pipes which one to select VCC

Flex Voltage

AKA: Flexible Voltage 

Flexible voltage products are those where the power consumption can accommodate a range of voltage instead of a fixed power setting. Indicators with flex voltage help reduce inventory cost by allowing OEMs to purchase only one indicator that can work in multiple designs with varying power needs.  

For example, VCC’s PLM50 Series can operate with power ranges between 5 VDC to 28 VDC. 

FlexVolt Technology

To accommodate a range of power needs in a single indicator, VCC developed FlexVolt technology for panel mount indicators and light pipes. With ranges from 5V to 28V, FlexVolt tech provides greater flexibility for engineers and OEMs alike.

Flush Lens

See also: Wide Flush Lens

A wide flush lens is an indicator lens that is attached to a human-machine interface or control panel and is “flush” or level with the panel as opposed to a raised indicator lens that would stick up above the panel’s surface.

Fresnel Pattern Lens

AKA: Fresnel Lens, Light Pipe with Fresnel Lens, PMI with Fresnel Lens

A Fresnel lens is an LED lens that has a flat top and uses concentric circles to help focus the light that is shining through it. Fresnel lenses can also soften the light beam and can be used in conjunction with various lens shapes like semi-dome, dome or flat. HMIs that use light pipes or PMIs can leverage the Fresnel lens to meet design and optical requirements.
rigid light pipe40 series panel mount indicator group



Harsh Environments

Working conditions can impact the life and performance of a PMI or status indicator. Harsh environments can include anything from being outdoors to exposure to harsh cleaning chemicals, dirt, vibration, heat or humidity.

Certain PMIs are designed for harsh environments, and others can be ruggedized with the addition of certain accessories, like O-rings or gaskets.

Explore the PMIs made for harsh environments in this brochure.

High-Dome Lens

AKA: Hi-Dome Lens

A high-dome lens is an LED indicator cover that sits prominently above the plane of the control panel and is rounded at the top. The dome shape provides the widest viewing angle, which improves visual communication when end-users need to maintain status from multiple positions, such as standing or bending down.

Hi-hat Lens

See also: Wide Hi-hat Lens

A hi-hat lens is an indicator cover that extends well beyond the surface of the control panel or HMI in a consistent shape with a flat top. Benefits of a hi-hat lens include a wider viewing angle that can also increase daytime visibility.

Read Ventless Grill Case Study

High-Vibration Environment

Some machines naturally move and vibrate during operation. For example, heavy industrial machinery can encounter a lot of vibrations during operation. 

To help keep the indicator in place, accessories like hex nuts can be added to secure them. Other design elements, like mounting type and device design can also prevent indicators from shifting in high-vibration environments.


AKA Human-Machine Interface

The HMI, or human-machine interface, is the control panel or surface where the indicator(s) of a device visually communicates the status to operators.


AKA hot spot

Proper light pipe design ensures uniform illumination of the indicator. When part of the indicator shines brighter than the rest, that is called a hot spot. 

In some applications, a hot spot is just an eyesore. In others, it can cause errors in readings and operations, depending on the design and how severe the hot spot is.

There are techniques to reduce hotspots, such as using a Fresnel lens to diffuse the light.


Ingress Protection or International Protection Ratings

See also: IP Rating

Ingress Protection or International Protection is a rating system used to indicate how protected a PMI is from both solids and liquids based on a numeric scale. Example: IP54

Solids are rated in the first number on a scale from 1-6)

Liquids are rated in the second number on a scale from 1-8

The higher the number, the greater the protection.

Download this IP rating chart for quick reference.

IP Rating

AKA: Ingress Protection, or IP

The IP rating or ingress protection rating is a numerical system used to indicate how protected a component is from particles such as dust or moisture. 

The first number indicates the level of protection from solids, and the second number indicates the level of protection from liquids. (The higher the better.)

Illumination Intensity

The illumination intensity of an LED or PMI is how bright the light shines. An LED’s intensity can be measured in many ways – watts, lumens, wavelengths, or even candelas, to name a few. 

Several factors contribute to the overall intensity of an LED, from the number of candelas or watts to the viewing angle of the lens.

Illuminated Communicator Control Panel

AKA: Control Panel, HMI

The illuminated communicator control panel is the interface of a machine or device where the end-user can view the machine’s status. It’s also called a control panel or human-machine interface. Using color, images and icons, the illuminated communicator control panel helps the user operate the machine safely.

Incandescent Indicator

An incandescent indicator is a status light that uses incandescent technology, the same tech used in a traditional light bulb. While cheaper than LEDs, incandescent indicators require more energy and burn out much faster. Often, OEMs can retrofit an incandescent indicator with LED technology for enhanced efficiency.




Lamp Life

See also: Life Expectancy

A bulb’s lamp life is the estimated duration of the light’s performance, as measured in hours. For LEDs, the lamp life is typically 50,000 – 100,000 hours, while an incandescent bulb’s lamp life may be 1,000 hours.


An LED is lighting technology that uses light-emitting diodes to illuminate a bulb. LEDs are very popular in indicators of all industries because of their:

  • Brightness – LEDs achieve full brightness in milliseconds and often shine brighter than other bulbs that use 10-20x the wattage
  • Reliability – LEDs don’t burn out and can last for several years, even in harsh conditions (with appropriate ruggedization)
  • Long life – an average of 50,000-100,000 hours
  • Energy efficiency – LEDs use a fraction of the energy incandescent bulbs do, making them a green alternative
  • Low power needs – can be powered with as little as 2V
  • Design flexibility – used with light pipes, light engines, and PMIs and are available in many color options
LED Adapter

Depending on the design of the device, an adapter may be used to secure the LED to the light pipe. Different adapters may be needed for through-hole and surface mount LEDs.

LED Holder

LED holders are the foundation of a panel mount indicator, used to encase the LED lamp for attachment to the device. The diameter of the mounting hole, working condition, and other design considerations will help determine the appropriate LED holder. Some include additional accessories for protection against moisture. Explore VCC’s LED holder options here.

LED Light Pipe

An LED light pipe is a tube made of plastic, acrylic, or glass that sits over an LED on one end of the device and carries light from the light source to the control panel or HMI.

LED light pipes coming in a range of colors and lengths, plus mounting options with their own pros and cons. For additional info on light pipes, check out our light pipe FAQs page.

red and green light pipe  light showing refraction



Lens Shape

LED lenses, or the caps at the top of them that are visible on the HMI, can take multiple shapes. Each one has its own benefits for the end-user, including:

  • High daytime visibility 
  • Wide viewing angle
  • Diffusing the light/uniform illumination
  • Aesthetic appeal

1092 series harsh environment 120 VAC VCC

Life Expectancy

See also: Lamp Life

Life expectancy of an indicator or bulb is the estimated duration of its performance. This number is typically measured in hours.

Sample bulb life expectancies: 

  • LED: 50,000 to 100,000 hours
  • Neon: 25,000 hours
  • Incandescent: 1,000 hours to 1,500 hours
Light Diffuser

In the world of opto-engineering and light pipe design, a light diffuser can be any material that softens or diffuses the light as it transmits it. This could be the lens of an LED or the face of a light pipe. The term light diffuser is often interchanged with light pipe.

Light Leaks

AKA – Light Loss

See also: What are light leaks?

Light leaks occur when some of the light that is meant to be transmitted to the exit point escapes at other places in the device, resulting in reduced efficiency and can cause errors in readings. 

Proper light pipe design techniques can be used to minimize light leaks, including:

  • Spacing of the LED and light pipe
  • Viewing angle of the light pipe face 
  • Angles and dimensions of the light pipe 

Learn more about how to minimize light leaks with the Light Pipe Design Guide.

light pipe light loss illustration


Light Pipe

See also: 

How do light pipes work?

What is a light pipe or light diffuser?

A light pipe is a cylindrical rod made of glass or synthetic materials that carries light from the light source to the desired exit point. 

Typically made of acrylic or polycarbonate, light pipes come in a variety of shapes, sizes, lengths and optical characteristics to meet any design specifications. 

Light pipes may seem simple at first glance, but there’s a lot of science and key design decisions that go into them, influencing production efficiencies, visual communication, safety and costs. Learn everything you need to know about light pipes here.

types of light pipes flexible light pipe and rigid light pipe

Light Pipe Position

The light pipe position is where and how it sits in relation to the light source. The closer the light pipe is to the LED or light source, the more you can minimize light loss. A general guideline is to use an LED with a narrow viewing angle of 160 degrees or less and make sure there’s no more than 0.05” between the LED and the light pipe position.

vcc light pipe design guide

Light Ray Simulation

Optical light simulations are used to calculate how a light pipe will perform within its device. This technique uses advanced software to project how and where any light leaks may occur for the purpose of optimizing and validating the design. 

Conducting light ray simulation can dramatically improve the design and efficiency of a status indicator or device.

light ray study for custom light pipe design

Long PMI Body

The body, or length of the PMI encasement or area that is threaded through the hole of the panel. Some control panels or HMIs on heavy-duty or ruggedized devices require a PMI with a longer body to accommodate the additional thickness of the panel itself. 

For example, VCC’s CDLB Series has a PMI body with longer threads that can accommodate panels up to .256” (6.5mm) thick.

long body indicator IP67



Light pipe design requires an understanding of how light travels when it shines through a medium, or material, such as water, acrylic, polycarbonate, silicone resins, and more.

The amount of light that travels, how the light bends and other factors will vary by the medium due to a phenomenon called refraction.

Micro-Fit Connector Dual Row

AKA: Dual Row Micro-Fit Connector

Connectors are used to bind electronic components together in lieu of soldering. A micro-fit connector dual row can be used to join board-to-board, wire-to-board or wire-to-wire configurations. 

For production efficiencies, VCC can add a dual row micro-fit connector to indicators rather than having to outsource that step to a third-party.

Learn more about connectors here.

Minimal Light Loss

In light pipe design, minimal light loss is the ultimate goal. While there will always be some minuscule amount of light loss, minimizing the light loss, or light bleed, is achieved with proper design and testing.

light pipe light loss animation

Moisture-Sealed Light Pipe

There are many indoor and outdoor applications where an indicator may be exposed to moisture — from raindrops to harsh cleaning chemicals. 

A moisture-sealed light pipe is one that includes additional security measures designed to keep moisture out so it doesn’t hamper performance. 

Examples include:  LMS Series and FLX_322 Series
Panel Mount Moisture-sealed Linear Light Pipesmoisture sealed flexible light pipe


  • Threaded mounting 
  • Additional seals or retainer rings

IP Ratings of IP65 or higher are moisture-sealed and dust-proof.

Mounting Hole Sizes

Mounting hole sizes are used to determine the appropriate PMI to accommodate a panel or interface. Every product will vary slightly in size. VCC’s offerings include indicator mounting hole sizes ranging from 0.16” (3.98mm) to 0.88” (22mm). 

PMIs with custom mounting hole sizes are available if a minimum quantity is ordered.


Narrow Viewing Angle

The viewing angle can indicate how focused the light will be, and is determined by several factors, including device design, spacing of LED and the light pipe and the lens face or shape of the light pipe. 

As a general rule, LEDs with narrow viewing angles are ideal for illuminating a small area on the panel, or if the light needs to travel longer distances from the LED to the exit surface.

narrow viewing angle led light pipe illustration


Operating Temperature

The operating temperature is the temperature range for safe operation of an indicator or light pipe. Factors like humidity, weather and stress can have a huge impact on operating temperature. 

In low-stress working environments, operating temperatures typically range from -100℃ to 100℃ for acrylic and -100℃ to 125℃ for polycarbonate. 

Operating temperatures will vary by product. Be sure to review the manufacturer’s specifications.


An O-ring is a gasket that goes around the indicator at the panel to keep out water, dust, debris, oil and other contaminants that could impact performance.


Panel Mount Indicator (PMI)

A panel mount indicator is a status indicator that affixes directly to the control panel or HMI instead of the inner components of the device. PMIs are used to communicate a device’s status, and can leverage LED, incandescent or neon technology.

PMIs are best suited for control panels with only a few status indicators and come in a variety of colors, sizes, mounting styles. Features such as the lens shape can help determine visibility. 

Explore VCC’s PMI selection here.

Panel-Mount Light Pipes

The opposite of board-mount light pipes, panel-mount light pipes are affixed to the control panel of the device instead of the PCB board. Panel-mount light pipes can be attached to the panel, or HMI, using “crushable” ribs or a retainer ring to seal off the surface.

LFB Series, LFC Series, LMC Series and LPCR Series

round rigid light pipe


AKA: Printed Circuit Board

A printed circuit board or PCB is a board that acts as the foundation of a device. It holds a chip or other electronic components in place. To address a range of design requirements, PCBs can be:

  • Single-sided
  • Double-sided
  • Rigid
  • Flexible
  • Multiple layers
  • Various shapes
  • Linked together in a single device

The PCB by itself is just the starting point. It must be designed and fitted with the proper electronic components, then tested and manufactured. At that point, it’s called a printed circuit board assembly.
custom pcb Assembly production manufacturing nearshore VCC


AKA: Printed Circuit Board Assembly

A printed circuit board assembly, or PCBA, is the printed circuit board with all of the electronic components installed, typically by soldering them. PCBAs are made up of several layers, each with its own job connecting the proper electrical charges to the right switches and other components.

They deliver a host of benefits, including: 

  • Space and production efficiencies
  • Easy installation & assembly
  • Reliable power source

Creating a full PCBA is a complex, multi-step process. VCC has in-house capabilities for design, fabrication and assembly.

vcc pcba nearshoringvcc medical device custom solution pcba

Pilot Light

AKA: Pilot Lamp

See also: Panel Mount Indicator

A pilot light is an illuminated lamp used to communicate a device’s status with end-users. Commonly referred to as a panel mount indicator, this light can leverage LED, incandescent or neon technology to communicate the device is on or some other machine function.


AKA polymethacrylmethylimid

PMMA is a material that can be used to make light pipes. It isn’t as malleable as acrylic or polycarbonate. Because of PMMA’s thermal resistance up to 170°C, the material is best suited for devices with heavy thermal loads.

Polycarbonate Light Pipe

Polycarbonate, or PC, is a one of the most popular materials used to make light pipes. 

Benefits include:

  • Excellent light transmission
  • Low UV transmission 
  • Can be easily molded
  • Durable and scratch-resistant
  • Relative low cost
  • Suitable for a wide range of applications

Press-fit is a mounting style where the PMI is attached to the panel using friction to create a secure bond. The indicator is pressed to the panel rather than using hardware to mount it in place.
Panel Mount Indicator

Prominent Bezel

See also: Bezel

A bezel is the housing or encasement around a panel mount indicator that can be made of steel or plastic. A prominent bezel is one that is longer and/or wider, typically to accommodate a thicker panel or for aesthetic purposes.


Quick-Connect Tabs

See also: Tab Terminals

PMIs can be connected to the power source within the device by wire leads or quick-connect tabs that use metal to conduct electricity and power the device. While slightly more expensive than wire leads, quick connect tabs provide greater flexibility in production and assembly.

Quick Installation

For OEMs, efficiencies in production and assembly can take place in a variety of ways. Quick installation of the PMI, light pipe or other components can occur with features including:

  • Quick-connect tabs
  • Connectors
  • Press-fit designs


Resistant to Shock and Vibration

AKA: Shock-Resistant, Vibration-Resistant

Many applications can put undue strain on a device due to electric shocks or vibration. Fortunately, there are tactics to help ensure an indicator is resistant to these harmful forces, such as:

  • Double-D mounting style
  • Hex nuts
  • Lock washers
  • O-ring gaskets

A resistor is a component that helps regulate and limit the electrical current that goes through a device. In some products, the resistor is optional, in others, it’s included. Be sure to view the specs on the manufacturer’s product datasheet. 

Resistors can also be customized for a range of indicator needs.

panel mount indicator with resistors

Rigid Light Pipe

Light pipes are either rigid or flexible. Rigid light pipes are designed to carry light a short, straight distance. They are also very inflexible and work well in devices where they don’t have to bend at all within the device to carry light from the light source to the HMI.
rigid light pipe example


Right-Angle Light Pipe

Some LEDs require 90-degree alignment to the light pipe. Those situations are where a right-angle light pipe is mounted directly to the PCB board directly over the LED. These rigid light pipes are available in multiple board-mount configurations, including:

  • 1-position
  • 2-position
  • 3-position  
  • 4-position 

board mount right angle light pipe

Right-Angle Through-Hole LED

An LED designed to be affixed to the PC board using two prongs that requires 90-degree alignment. Devices with wave solder circuit boards are ideal for right-angle through-hole LEDs.
Right Angle Thru-hole PCB Mount LED Indicators

Right-Angle Surface-Mount LED

An LED that is mounted to the HMI or panel that requires a 90-degree alignment with the light pipe. Flexible right-angle light pipes are a good fit for right-angle surface-mount LEDs, as they are affixed to the PC board.

Ruggedized Light Pipe

A ruggedized light pipe is one that includes additional features or components that make it more suitable for tough working conditions, such as high-humidity, moisture, or vibration.

moisture sealed light pipe

Ruggedized Indicators

When the working conditions are harsh due to weather, moisture or vibration, ruggedized indicators are those that use additional accessories or design features to help them provide reliable operation in bad working environments.

Discover VCC’s ruggedized indicator selection here.

Refractive Index

When light shines through a medium like acrylic, the ray of light shifts before at the exit point. It’s a phenomenon called refraction. To ensure the light traveling through a light pipe shines where it’s supposed to, the Refractive Index must be factored into the design decisions. 

It’s a measure of how much of the light ray gets bent when it hits the surface of the medium. 

Sample Refractive Indices:

Air = 1.003

Water = 1.33

Acrylic = ~ 1.49


AKA: Light Pipe Retainer

A retainer is an additional accessory used to secure a light pipe in place or provide added level of protection from dust, moisture or vibration.


Sealed Indicator

A sealed indicator is a PMI or light pipe that has added reinforcements to keep out dust and moisture. Methods for sealing include accessories, design features such as:

  • O-rings
  • Gaskets
  • Hex nuts
  • D mounting styles

Semi-Dome Face

A semi-dome light pipe face is the middle ground option between a full dome and a flat face that is flush with the panel. The semi-dome face provides a wide viewing angle and helps minimize hot spots that could disrupt visual communication.

Semi-Dome Lens

PMIs with a semi-dome lens split the difference between a full dome and a flat lens face. The semi-dome shape provides some of the advantages of a rounded lens without being too prominent on the panel. Benefits include minimizing hot spots and a wider viewing angle.

Shorter Supply Chains

Global supply chains are full of risk, as delays at any point in design, production, manufacturing and shipping could cause severe financial loss. By choosing suppliers nearshore instead of overseas, OEMs can take advantage of shorter supply chains which mean less distance products need to travel, saving time, money and potential disruptions. 

Learn how to shorten supply chains and reduce risk here.

Silicone Resins

Another material available for light pipe fabrication, silicone resins are also used for LED lenses. For outdoor applications or medical equipment, silicone resins are a great solution because they don’t yellow under UV and are safe when applied to skin.


Snap-fit is a PMI mounting style where the PMI rests inside the panel mounting hole and snaps into place with a metal connector (rather than using wires). Because the PMI can fit securely to the HMI without additional hardware or steps, snap-fit panel mount indicators can save time and money during production.

Snap-Fit with “D” Mounting

Snap-fit with “D” mounting is an attachment method where the PMI is inserted into a D-shaped mounting hole on the panel. The shape helps protect the device from rotating or coming loose due to vibration. Ideal for industrial applications, the snap-fit with D mounting is simple to install.

Speed Nut

A speed nut is a push-on accessory for panel mount indicators that helps protect them in high-vibration working environments. Sometimes the speed nut is included with the PMI, others, it’s an add-on part. Refer to the specific product’s datasheet for details.

speed nut led1092 Blue LED Indicator with Speednut

Surface, exit

See also: What is the exit surface of a light pipe?

A light pipe contains two openings: one at the light source, and one where the light needs to shine at the interface or control panel. The location where the light shines out is the exit surface.

Surface-Mount LED


A surface-mount LED is one that affixes to the PC board. Also known as SMD (surface-mount devices) LEDs, these components can provide production efficiency during installation and assembly. Because SMD LEDs don’t contain wire leads, they are soldered directly to circuit boards using tiny metallic contacts.

SMD LEDs are smaller and more energy efficient, making them ideal for compact designs. 

Surface-Mount Technology


Surface-mount technology or SMT is the method used to attach surface-mount LEDs or other electrical components on a printed circuit board’s surface. SMT delivers a range of benefits for OEMs and designers, including:

  • Reduced size
  • Lighter weight 
  • Cost efficiencies
  • Design flexibility
  • Automated production

Storage Temperature

Not to be confused with operating temperature, the storage temperature is the range at which the light pipes can be warehoused with minimal degradation. In low-heat, low-humidity environments, storage temps for acrylic and polycarbonate light pipes are typically between -100℃ and 25℃.  

Storage temperatures will vary by product. Refer to your manufacturer’s specifications.


Tab Terminals

Panel mount indicators can be attached to the motherboard or power source in a few different ways. One of those ways is by using tab terminals. The metal on the tabs transfers the current from the power source to the PMI. Tab terminals are faster to install, delivering production efficiencies for OEMs.

Threaded Housing

A threaded housing is the plastic or metal sheath that goes over the PMI that is ribbed so it can be “threaded” into the panel, and secured with mounting hardware such as a lock washer or hex nut to provide additional stability through high-vibration operation.
panel mount indicator

Through-Hole LED

A through-hole LED is one that is mounted from the panel or the back of the device instead of the printed circuit board. The LED is mounted using two leads and can be a great fit for PCBA devices.

Depending on the design of the device, flexible light pipes are best for through-hole LEDs.
led through hole1.65 mm through hole led5mm through hole led

Total Internal Reflection


Light pipes must reflect light if the goal is to carry it around corners. Total internal reflection occurs when the angle at which light is reflected when it shines through a surface is greater than a certain limiting angle known as the critical angle.

TIR helps the light bounce back toward its intended exit point instead of being lost or leaked. Learn more about TIR in this blog post.

light pipe design refraction


AKA: Semitransparent

Translucent is a visual characteristic used to describe objects that allow a lot of light to shine through but are not fully see-through.


AKA: See Through

Objects that are transparent, such as a lens or bulb, completely see-through, allowing light and objects behind them to be clearly visible.

Tri-Color LED

A tri-color LED is a lamp that has the ability to change color three times without requiring additional space on the HMI or panel. Typical color combinations for tri-color LEDs include: red, yellow, and green. 

Need a different color combination? VCC can help with a custom PMI design.


UL Listing

If a finished product meets all of the UL standards and requirements for safety, it earns a UL listing for display on product specs and marketing collateral to reflect it has been tested and is approved for consumer use in a specific category.
ul listed logo 

UL-Recognized Component

Because UL, a third-party testing company, can’t certify an entire product based on one aspect of the electronic elements, individual products, like LEDs or PMIs that meet the safety standards are designated UL-recognized components.

ul logo

UL Rating

UL is a third-party certification company that conducts testing and sets the industry standard for safety for a range of product categories worldwide. 

Depending on the type of device or product, different ratings will be used. For example:

UL Listed – certification of the entire product vs. its components 

UL-Recognized – for components only – not complete, market-ready products

Different marks are used to indicate UL status by country or region, such as Canada, US and Europe.

User Experience


User experience is the type of outcome operators will have with your product. Designing for the user experience should work along with designing for the user interface — the look, feel and functionality of the device. 

For an ideal user experience, design for an interface with these attributes:

  • Useful
  • Usable
  • Desirable
  • Findable
  • Accessible
  • Credible

Learn how in this our user interface and experience design guide.

User Interface

See also: HMI

A user interface is the control panel or other location where device status is communicated with an end-user. The more intuitive and seamless a user interface is, the safer the operation of that machine will be. There are many methods designers can use to enhance the user experience through the user interface.

Get tips on how to design a better user interface here.

User Interface Design


User interface (UI) design encompasses the look, feel and functionality of the device. From product aesthetics to the visual communication and controls used within the device, user interface design can really make or break a product. Using user-centric design (UCD) principles is a great way to develop, test and optimize your interface until you land on a design that will work well in its actual environment, being seamless, reliable and intuitive.

Uniform Illumination

A goal of any light pipe’s design, uniform illumination is where the entire indicator surface has even light instead of hot spots in certain areas.

UV-Resistant Lens

The sun’s UV rays can be damaging to equipment as well as our skin. UV-resistant lenses prevent PMIs from fading or discoloration in outdoor applications and can help extend their life and maintain accurate status indication.


V-0 Vertical Burn Flammability Rating

See also: Flammability Rating

To attain the UL94V-0 flammability standard — the best in the industry — a series of burn tests are conducted on electronic components.

The V-0 vertical burn flammability rating occurs when the burning stops within 10 seconds after two applications are applied of a flame to a test bar, each being 10 seconds. No flaming drips are allowed. V-0 is the best rating possible for this test.

V-1 Vertical Burn Flammability Rating

To attain the UL94-V0 flammability standard a series of burn tests are conducted. The V-1 burn rating occurs when the burn stops within a minute after a flame is held to a test bar for two applications that are ten seconds each. No flaming drips are allowed for the V-1 rating, which is the second-highest score for this test.

V-2 Vertical Burn Flammability Rating

The UL94-V0 flammability standard is the highest in the industry for safety. The V-2 vertical burn rating occurs when burning stops after 60 seconds when two flame tests are conducted, each for 10 seconds. Flaming drips are allowed. V-2 is the lowest rating in this series, with V-0 being the best.

Vandal Resistant

Indicators that are vandal resistant are designed in such a way that they have added protection from intentional tampering that could impact performance. Techniques such as additional accessories or designing a product with key electronic components located far away from the HMI are ways to enhance the vandal resistance.

Visual Communication

AKA: Visual language

Visual communication is the combination of color, icons and light cadence within an HMI or control panel that helps the end-user maintain safe operation. There are several best practices designers can implement to achieve safer, more intuitive visual communication. 

Learn how in our Status Light Indicator Guide.

Visual Language

AKA: Visual Communication

In status indicator design, visual language is the collective experience of elements that work together to communicate with the operator or end-user:

  • The LED colors used
  • Number of indicators
  • Light patterns (on-off, flashing, etc.)
  • Icons/visuals
  • Numbers

Effective visual communication can impact reaction times and safety.

status indicator design guide


Waterproof Light Pipe

As the name suggests, waterproof light pipes are those that have a high level of protection from liquids like sweat, blood, or rain. 

The IP rating of a component will help determine how well the product can withstand exposure, with ratings ranging from protection against water drops to full submersion up to 3.9 meters.  (See IP rating below for additional info)

LMS Series and FLXR Series

Panel Mount Moisture-sealed Linear Light Pipes


Wide Flush Lens

A wide flush lens is a type of indicator lens that is even or “flush” with the HMI or control panel. It’s also wide in diameter to accommodate larger panels and easy viewing.

Wide Hi-Hat

A wide hi-hat is a type of indicator lens that extends well beyond the control panel rather than being flush with it that is also prominent in width for better viewing.

Wide Viewing Angle

Several factors can determine the viewing angle, including the shape of the lens face, as well as additional textures like a Fresnel lens. 

The greater the viewing angle, the more light is shown and at different perspectives, but the overall intensity is decreased. A wide viewing angle, typically 160 degrees or higher, works best in devices where the LED will illuminate a large area or the light source is very close to the panel.


Wire Leads

Wire leads are one method of attaching PMIs to the board or power source of a device. These wires can be customized in length, and most PMIs with wire leads come in multiple standard length options.

Wire-to-Wire Crimp Housing

See also: Connectors

In order for the indicator to be installed and properly powered with the rest of the device, the wires must connect to the power source. Wire-to-wire crimping is one solution for ensuring all components are properly connected and secure. The other method is soldering the wires to the board or power source. 

VCC has in-house capabilities to provide added efficiencies in production. Learn more here.





A material used to make light pipes, Zeonex is biocompatible and highly resistant to moisture and humidity, making it ideal for medical applications.

Zero Light Loss

When no light is lost from Point A to Point B within a light pipe, zero light loss is achieved. While truly zero is impossible to obtain, there are several products available that get pretty darn close.

LPCM Series
no light loss light pipe illustration light bleed lpcm

Want to learn even more about status indicators?

Check out these handy design guides
Light Pipe Design GuidePCB Design Guide

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