SPM100 Light Guide
SPM100 PMMA Light Guide for Scintillation Detector Coupling
SPM100 Light Guide is a cast PMMA optical guide used to transfer scintillation light from a scintillator to a light sensor such as a photomultiplier tube, SiPM, silicon photodiode or custom readout module. It is used when the scintillator shape, active area or detector housing does not directly match the photosensor geometry.
Unlike SP101, SP102, SP121, SP122 or SP123 plastic scintillators, SPM100 is not the primary radiation-sensitive material. Its role is optical coupling: collecting, shaping and guiding visible scintillation photons from the detector element to the readout device with controlled geometry, polished surfaces and suitable refractive-index matching.
ATR Crystal can machine SPM100 light guides into rectangles, cones, fishtails, wedges, strips, tapered blocks and drawing-defined shapes. Custom dimensions, optical polishing, edge treatment, coupling-face quality, wrapping method and detector assembly requirements can be reviewed for radiation monitoring instruments, large-area detector systems and OEM scintillation detector designs.
Light Guide Role in Plastic Scintillator Detectors
SPM100 is an optical light guide rather than the active scintillator material. It is used when scintillation light from a plastic scintillator panel, bar or block needs to be transferred to a PMT, SiPM or photodiode. For the full detector material selection path, review the plastic scintillator selection guide.
Applications of SPM100 Light Guide
Scintillation detector light collection and optical coupling
PMT, SiPM and photodiode readout assemblies
Plastic scintillator paddles, panels and bars
Crystal scintillator detector modules with geometry transition
Radiation monitors, portal monitors and custom detector housings
Automotive lighting and optical light-pipe prototypes requiring PMMA guides
Advantages of Cast PMMA Light Guides
- Good optical clarityPMMA provides useful visible-light transmission and a refractive index around 1.49, making it suitable for many scintillator coupling designs.
- Low densityThe low density of PMMA helps reduce weight in large-area detector panels, portable instruments and long light-guide structures.
- Custom geometryRectangular, conical, fishtail, wedge, strip and tapered designs can be machined according to sensor area and scintillator size.
- Cost-effective processingPMMA light guides are generally more economical than many optical crystal or glass coupling components.
- Mechanical practicalityCast PMMA can be machined, polished and integrated into detector housings when mechanical stress and chemical exposure are properly controlled.
- Detector assembly supportCoupling face quality, optical grease interface, wrapping method, reflective film and mechanical housing can be reviewed together.
Available SPM100 Light Guide Shapes
SPM100 can be supplied as a simple light guide or as part of a detector coupling assembly. Final geometry should be matched to scintillator size, sensor area and housing design.
| Shape / Format | Common Use | Design Notes |
|---|---|---|
| Rectangular block | Direct coupling between flat scintillator and sensor window | Useful when the input and output areas are similar or when a short optical spacer is needed. |
| Tapered block | Area transition from scintillator panel to smaller photosensor | Taper angle should be reviewed to reduce avoidable light loss and total internal reflection issues. |
| Conical guide | Circular PMT or SiPM array coupling | Used when a round sensor window must be matched to a different detector geometry. |
| Fishtail guide | Wide scintillator strip or panel readout | Helps transition a wide input face to a smaller sensor area in large-area detector designs. |
| Wedge guide | Space-limited detector housing and angle coupling | Useful when detector mechanics require an offset or angled optical path. |
| Flat strip / bar | Simple light transport or edge readout | Can be used with plastic scintillator strips, panels or custom readout layouts. |
| Drawing-defined part | OEM detector module or prototype assembly | Provide CAD drawing, tolerance, polishing, coupling face and packaging requirements for review. |
Properties of SPM100 Light Guide
The following values are based on the original SPM100 page and typical cast PMMA behavior. Final limits depend on PMMA grade, thickness, machining, surface finish and operating environment.
| Parameter | Value / Option | Engineering Notes |
|---|---|---|
| Material | PMMA, polymethyl methacrylate | Optical acrylic material used for visible-light guidance and detector coupling. |
| Density | 1.19 g/cm3 | Consistent with typical cast acrylic / PMMA data. |
| Refractive index | 1.49 | Typical visible-light refractive index of PMMA; coupling medium should be selected accordingly. |
| Manufacturing technique | Casting | Cast PMMA is suitable for machined and polished optical light-guide parts. |
| Operating temperature | Low-temperature use to -95 C may be reviewed | The original page listed -95 C only. Maximum service temperature, thermal cycling, adhesive, grease and housing stress must be confirmed for the final assembly. |
| Common shapes | Rectangle, cone, fishtail, wedge, strip and custom geometry | Geometry is normally defined by detector area, sensor area and housing constraints. |
| Surface processing | Optical polishing, edge treatment and coupling-face control | Surface finish and edge quality influence light collection efficiency. |
| Integration options | Scintillator coupling, wrapping and detector housing support | Can be reviewed together with PMT, SiPM, photodiode or custom readout plans. |
Detector Coupling Design Notes
A light guide should be specified together with the scintillator and sensor, not as an isolated mechanical part. Important design factors include scintillator emission wavelength, sensor active area, optical grease or adhesive, refractive-index matching, wrapping material, surface finish, guide length, taper angle, edge polish, housing pressure and expected operating temperature.
For large plastic scintillator detectors, a fishtail or tapered PMMA light guide is often used to collect light from a wide scintillator strip and deliver it to a smaller PMT or SiPM readout area. For compact crystal detector modules, a short rectangular or conical guide may be used as a spacer, geometry adapter or optical coupling element.
SPM100 vs. Related Plastic Scintillator Products
SPM100 should be selected when the detector needs optical coupling or geometry transition. If the requirement is direct radiation detection, choose the appropriate plastic scintillator material or coated scintillator product instead.
| Product | Main Role | Typical Structure | Best Fit |
|---|---|---|---|
| SPM100 Light Guide | Optical light transfer and sensor coupling | Cast PMMA light guide | PMT/SiPM coupling, geometry transition and custom detector assemblies |
| SP101 Plastic Scintillator | Active plastic scintillator | Blue-emitting plastic scintillator | Gamma-ray, X-ray and general ionizing-radiation detection panels |
| SP102 Plastic Scintillator | Active thin plastic scintillator | Polystyrene-based scintillator, typically 0.25-1 mm thick | Beta-ray measurement and thin charged-particle detector designs |
| SP121 Plastic Scintillator | Alpha/beta detection | SP102 base with ZnS(Ag) coating, typically 4.5 mg/cm2 | Dual alpha and beta radiation measurement |
| SP122 Plastic Scintillator | Low-energy gamma detection | SP101 base with ZnS(Ag) coating, typically 8-10 mg/cm2 | Low-energy gamma-ray detection down to about 40 keV according to product design |
| SP123 Plastic Scintillator | Alpha detection | PMMA substrate with ZnS(Ag) coating, typically 4.5 mg/cm2 | Large-area alpha-ray detection panels and custom formats |
How to Specify a PMMA Light Guide
For an accurate SPM100 quotation, provide the scintillator type, scintillator dimensions, emission wavelength if known, sensor type, sensor active area, light-guide shape, input/output face size, total length, taper angle, polishing requirement, optical coupling method, wrapping requirement and housing drawing. If the guide will be used at low temperature, high temperature or in a chemically exposed environment, that condition should be stated clearly.
SPM100 can be supplied for prototype testing or recurring production. For detector systems, ATR Crystal can also review the complete optical path, including scintillator material, PMMA guide, coupling surface, reflective film, sensor interface and mechanical housing.
SPM100 Light Guide RFQ Checklist
Providing the following information helps ATR Crystal review feasibility and quote more accurately.
| RFQ Item | Information to Provide |
|---|---|
| Application | Radiation detector, plastic scintillator panel, crystal detector module, PMT/SiPM coupling, automotive lighting or other optical guide use. |
| Scintillator and sensor | Scintillator material, scintillator size, sensor type, sensor active area and required coupling method. |
| Geometry | Rectangle, cone, fishtail, wedge, strip, tapered part or custom drawing-defined shape. |
| Dimensions | Input face, output face, total length, thickness, taper angle, chamfer and tolerance. |
| Optical processing | Surface polish, edge finish, coupling face quality, wrapping material, optical grease or adhesive requirement. |
| Operating condition | Temperature range, thermal cycling, vibration, chemical exposure, housing pressure and assembly method. |
| Order information | Prototype quantity, batch quantity, inspection requirement, packaging and delivery schedule. |
