Stem LED

Stem LEDs – Metal Can TO-Packaged Emitters (UV–IR)

The Stem LED category refers to LEDs packaged in metal stem (or can) packages, typically with a glass lens or window – essentially similar to traditional transistor‑style or lamp‑style hermetic packages. These often go by names like TO‑18, TO‑46, TO‑5, etc., depending on size. Tech‑LED’s Stem LEDs are characterized by their robust construction and precision optics. They usually consist of an LED die mounted on a metal header (the “stem”), with leads for electrical connection, and capped with a metal enclosure with a lens (like a tiny bulb) or a flat window. These packages offer hermetic sealing, protecting the LED die from moisture and contaminants, and can incorporate features like internal reflectors or ball lenses to collimate the light. Stem LEDs are typically used in applications requiring high reliability and often in conjunction with fiber optics or sensing – such as optical sensors, scientific instruments, medical devices, and high‑end industrial systems. Tech‑LED produces stem LEDs across a broad wavelength range, including infrared emitter diodes, visible colored diodes, and even UV LEDs in stem packages for specialty uses.

Key Features of Tech‑LED Stem LEDs

• Hermetic Sealing & Reliability: Stem LEDs are packaged in metal/glass cans that are hermetically sealed – no plastic to degrade, and no path for moisture ingress. This makes them extremely reliable in harsh environments (military, aerospace) and over long lifetimes. For example, our TO‑18 packaged IR LED can operate in high humidity or even under vacuum without performance change, outlasting typical epoxy‑encapsulated LEDs. They also handle wider temperature ranges. This reliability is why stem LEDs are often used in safety‑critical sensors and long‑term deployments (like oil well sensors or space instruments). Tech‑LED ensures all our stem LEDs are sealed to spec; many follow MIL‑STD hermeticity standards (with He leak tests, etc.) if required. We also use high‑purity materials (Kovar or alloy headers, hard glass lenses) that match thermal expansion for the seal integrity.
• Narrow Beam / Precision Optics: Many stem LEDs come with built‑in lenses or reflectors that create a focused, narrow beam output. Unlike an epoxy LED where lens shaping is more limited, in a metal can we can integrate a spherical lens (often molded glass) directly over the die, achieving beam divergences as low as a few degrees. For instance, our 5 mm can package with ball lens can produce a ~±5° beam – useful for fiber coupling or long‑distance sensing. Some designs include an internal reflector cup under the die to gather sideways emission and a lens for forward collimation, maximizing on‑axis intensity. This is beneficial for IR remote transmitters or sensor emitters can be enhanced with our LED stem technology for improved performance. Where you want most light going straight, LED stem lights provide optimal directionality. Tech‑LED’s stem LED lineup includes versions specifically optimized for fiber‑optic injection (the LED sits at the focal point of a tiny lens to shoot light into a fiber core efficiently) and versions for free‑space signaling (like an IR LED with a narrow 3° beam for communication across a factory floor). The metal can also allows easier attachment of additional optics if needed, like threading on a small collimator, something you can’t do with plastic LEDs easily.
• Heat Dissipation and Higher Drive: The metal stem packages typically have the LED die mounted on a metal slug that is thermally conductive, enhancing the efficiency of LED light output. Combined with being often larger in volume than a plastic LED package, they can handle higher drive currents and dissipate heat better. A LED in a TO‑5 can might be driven to, say, 100 mA continuous where the same die in a plastic 5 mm might only do 20–30 mA safely because the can acts like a heatsink. This means LED light can significantly enhance visibility in various applications. Brighter output is achieved with our advanced LED stem technology, ideal for various lighting applications. when needed. We exploit this for certain IR LEDs: our LED stem technology provides improved performance. high‑power 940 nm stem LED can be pulsed at high currents (like 1 A) for use in things like active IR illuminators or rangefinders, delivering strong bursts without damaging the die due to the thermal mass of the package. For laser diode replacements at short range, high‑drive LEDs in cans are attractive for eye‑safe systems. Additionally, the robust leads and package allow easier aerospace or automotive integration where vibrations exist – the die is solidly bonded to metal, less risk of fatigue or cracks vs wire‑bonded plastic parts under constant vibration.
• Customization for Sensors (LED+PD combos): Stem LED packages are often used not just for emitters but also detectors (photodiodes, phototransistors). Tech‑LED can create matched emitter‑detector pairs in identical or complementary can packages, which is useful for reflective or transmissive sensor assemblies (like a modulated IR LED and a photodiode across a gap for object detection). Moreover, the stem format sometimes allows two chips in one can – for example, an LED and a photodiode in one hermetic package, aligned in a specific geometry. We have capabilities in producing custom two‑in‑one packages (much like our two‑tone photodiode concept, but LED+PD), which can be used for compact optocouplers or analytical devices. While not a standard product, this flexibility underscores how the stem platform can integrate multiple components. More commonly, we ensure our stem LEDs and photodiodes have optical axes that can be easily aligned. For instance, an LED in a TO‑18 and a photodiode in a TO‑18 can be placed facing each other in a tube to make a very stable optical switch that’s impervious to ambient light – a design often used in industrial automation. We ensure the mechanical tolerances so that these align correctly when assembled in customer hardware.
• Special Wavelengths and High Radiance: Stem LEDs are available in all wavelengths we cover, but they especially shine (pun intended) at unusual wavelengths where maximum performance is needed. For example, our 280 nm UVC LED in a metal can is offered for scientific instruments (the can protects the LED and the lens focuses the output for, say, a water quality tester). Similarly, we have blue and green stem LEDs that provide very pure color with narrow beam for optical pumping or calibration light sources. In general, whenever an LED needs to behave almost like a point source (high radiance), the combination of a small die and a focusing lens in a stem package achieves that. This is why, historically, small visible LEDs in cans were used in early fiber‑optic communications before lasers – the tiny emitting area and lens allowed decent coupling into multimode fiber, similar to how LED light is used in modern displays. We continue this legacy with our modern LED dies: a 650 nm red stem LED of ours can launch significant light into a plastic fiber for short‑distance communication (used in some industrial comms and automotive MOST networks). For calibration, say an optical tachometer Uses a stem red LED to get a clean spot on a rotating reflector – the precision ensures consistent results each use, particularly in LED light displays.

Applications of Stem LEDs

• Optical Sensors and Encoders: Many industrial and consumer sensors rely on stem LEDs. An example is the smoke detector: a common design uses an IR LED and photodiode in a T‑shaped chamber; often these IR LEDs are in a can package (for stability over years) emitting into the chamber, and when smoke particles scatter the IR, the photodiode picks it up. Tech‑LED’s hermetic IR emitters ensure the device remains calibrated over a decade without LED degradation (critical for life safety). Another example is rotary and linear encoders for motion control – a stem IR LED shines through a code wheel and a photodiode array reads it. The collimated beam from the stem LED yields crisp shadows and hence precise position readings, making it ideal for display applications. Reflective optical sensors In things like line‑following robots or paper edge detectors, stem lights are used because they can focus the light to a small spot and receive a small spot, increasing resolution. Essentially, any sensor that historically might have used a small incandescent lamp often has a stem LED replacement now – older lab instruments replaced tungsten bulbs with our broadband white or specific‑color stem LEDs to reduce heat and maintenance.
• Fiber Optic Communication (short range): While lasers dominate long‑distance telecom, short‑range fiber links (like those inside aircraft or cars, or industrial interlocks) sometimes use LED sources for simplicity and eye safety. Our 1300 nm and 820 nm stem LEDs are designed to couple into multimode fibers for data rates of a few tens of Mbps over maybe tens to a couple hundred meters (like in proprietary network loops). For instance, some avionic systems send signals over fiber using an 820 nm LED in a TO‑46 can and an Si photodiode at the other end – this avoids electrical interference in the plane. Similarly, in automation, a controller might have plastic fiber runs to sensors using red or green stem LEDs as transmitters. We provide the consistency and longevity needed so these LED‑based links remain stable (LED center wavelength shifts very little with time compared to, say, VCSEL lasers). The automotive MOST (Media Oriented Systems Transport) network used a red LED at ~650 nm in a lens can to send audio data via plastic optical fiber – a canonical example of mass deployment of stem LEDs in a data context.
• Medical & Scientific Instruments: Laboratory devices often include LED sources in hermetic packages to ensure measurement stability. For example, a blood oximetry bench device might use stem red and infrared LEDs to precisely measure absorption of blood samples (as opposed to disposable probes which use cheap parts; the lab unit uses high‑precision hermetic parts for calibration and long‑term use). We supply calibration LEDs (with known intensity and spectrum) in hermetic cans for spectrophotometers – e.g., a 470 nm and 635 nm LED in cans are used to calibrate the wavelength accuracy of certain spectrometers because their output is stable and lineshape known. In dental or dermatological tools, UV stem LEDs might be used (hermetic sealing protects the UV die longevity). Another interesting field is biophotonics: devices that measure tissue properties or do imaging might incorporate a bank of stem LEDs of various wavelengths (since they often need narrowband light). The hermetic LED ensures no contamination of samples (some plastic might outgas or leach under certain conditions; metal‑glass won’t). Additionally, space and defense scientific applications (like a satellite needing a small beacon LED or a light source for an optical sensor in orbit) will choose hermetic LEDs due to radiation hardness and reliability – our stem LEDs can be and have been radiation‑tested for such scenarios.
• Infrared Remote and Ranging: Many consumer IR remotes just use plastic 940 nm LEDs, but high‑end or long‑range IR communications sometimes upgrade to a stem LED for a tighter beam and more power. For example, an IR audio transmitter for assistive listening in a theater may use a cluster of stem IR LEDs behind lenses to cover the audience – the hermetic LED can be driven harder to get the necessary distance (covering a whole auditorium) and its lens ensures the IR is directed. In LiDAR‑like applications where lasers are too costly or dangerous, a pulsed stem LED array at 850 nm or 940 nm can do low‑resolution ranging (for security perimeters or vehicle backing sensors). The advantage is the wide safe beam – an array of our narrow‑beam stem LEDs can flood an area with invisible light and a synchronized detector times reflections. Not as precise as a laser LiDAR, but much cheaper and eye‑safe. Our ability to supply matched emitter‑detector pairs in hermetic packages greatly benefits such designs.

What are the features of stem LED lights?

Stem LED lights are known for their bright illumination and energy efficiency. They provide excellent visibility for various applications, including outdoor lighting and bicycle safety. These lights are often designed to be durable and weather-resistant, making them ideal for outdoor use.

How do I install a valve stem cap with LED technology?

Installing an LED valve stem cap is straightforward. First, remove the existing valve stem cap from your bicycle or vehicle tire. Next, take the LED valve stem cap and screw it onto the valve stem, ensuring a snug fit. The battery inside the cap will activate the light, providing enhanced visibility during rides.

What is the description of a universal LED fixture for outdoor lighting?

A universal LED fixture for outdoor lighting typically includes a durable housing that can adapt to various environments. It often features adjustable angles for optimal light placement and is equipped with energy-efficient LED technology. These fixtures are designed to provide bright illumination while enhancing the appearance of outdoor spaces.

In summary, Stem LEDs remain indispensable for specialized roles that demand top-tier reliability, optical precision, and often integration into legacy optical layouts. Tech-LED’s offerings, backed by examples and references, highlight how these “classic” LED packages continue evolving – from enabling smoke detection to providing precise lab measurements to serving communications in novel environments. Our commitment to quality (often exceeding standard LED qualification) in this category ensures that when a design calls for a hermetic or stem LED, Tech-LED delivers a component that will perform consistently, accurately, and durably, often for the entire life of the product in which it’s embedded.