1. Features
- High Transmission: Long Pass Filters exhibit high transmission properties across specified wavelength ranges, ensuring minimal energy loss in the desired spectral region.
- Broad Range of Wavelengths: Available across various cut-on wavelengths from 335 nm to 1600 nm, catering to a wide range of applications.
- Customizable Specifications: Custom options available for optical density (OD), cut-on wavelength, and specific transmittance requirements.
- Durability: Conforms to high standards for adhesion, abrasion, and environmental testing, ensuring long-lasting performance even in demanding conditions.
- Versatile Applications: Widely used in fields such as biomedical imaging, digital imaging, fingerprint recognition, and environmental monitoring.
2. General Description
Shape Optics Technologies Pte Ltd (SOT) offers a range of high-performance Long Pass Filters designed for precision optical applications. These filters allow light transmission above a certain wavelength while blocking shorter wavelengths, making them ideal for a variety of scientific, industrial, and security applications. SOT’s long pass filters are crafted to meet the highest standards, with exceptional transmission capabilities and robust physical characteristics.
The filters are primarily utilized in fields like biomedical imaging, fingerprint recognition, color measurement, and environmental monitoring, where accurate detection in the infrared or visible spectrum is required. Whether you are looking for high optical density or specific wavelength cut-off properties, these filters can be customized to meet the unique needs of your project.
3. Spectrum Transmission Curves
The following spectrum transmission curves illustrate the effectiveness of SOT’s long pass filters across different wavelength ranges. For standard models or customization based on specific wavelength ranges, SOT can cater to your needs.
4. Coating Quality
- Adhesion Test: Compliant with MIL-C-675C military standards, an adhesion test involves applying a tape that meets LT-90 specifications onto the lens film layer. The tape was affixed fully and then removed vertically. This procedure was performed three times, resulting in no blistering or peeling.
- Temperature Test: Test pieces were subjected to temperatures of -62±1℃ and 71±1℃. After maintaining them at room temperature (16℃~32℃) for two hours, the adhesion test was repeated, confirming no film detachment.
- Abrasion Resistance Test: Conforming to MIL-C-675C and CCC-C-440 standards, the abrasion resistance test involved a gauze tester applying a minimum force of 1.0 lbs (0.45 kg) to the film. This was repeated 25 times with gauze widths of 1/4 inch (6.4mm) and 3/8 inch (9.5mm), ensuring no damage occurred to the film surface.
- Humidity Test: The test piece was placed in a controlled temperature and humidity chamber set to 49 ±2℃ and 95%~100% humidity for 24 hours. The film remained intact, with no peeling, scratches, or other defects.
- Solvent and Cleaning Testing: Following MIL-C-675C specifications, test pieces were exposed to room temperature conditions (16℃~32℃) and tested with acetone and alcohol for at least 10 minutes each. After air drying and subsequent cleaning with a cotton cloth soaked in alcohol, the film surface showed no signs of peeling or scratches.
- Salt Spray Test: After 100 hours in a 35°C environment with a 5% saltwater concentration, the film showed no signs of damage.
5. Standard Specifications
| Model | Cut-on Wavelength (nm) | Transmittance | Wavelength Range | Optical Density (OD) |
| NH-LP335 | 335±5 | T≥90% | 340-500 | OD≥3@200-320 |
| NH-LP400 | 400±5 | T≥90% | 410-1100 | OD≥3@350-380 |
| NH-LP410 | 410±5 | T≥90% | 420-1100 | OD≥3@350-390 |
| NH-LP420 | 420±5 | T≥90% | 430-1100 | OD≥3@350-410 |
| … | … | … | … | … |
(Additional models are available and can be customized as required.)
6. General Applications and Examples
Long pass filters are utilized across a wide spectrum of applications. The primary industries and uses for SOT’s long pass filters include:
- Biomedical Imaging: Long pass filters are used in medical imaging equipment to block unwanted light and focus only on the relevant wavelengths for enhanced diagnostic clarity.
- Fingerprint Recognition: In security and biometric applications, long pass filters help improve the contrast between fingerprint features and the background.
- Digital Imaging and Color Measurement: Essential in applications that require accurate color differentiation and high-resolution imaging, such as in photography, cinematography, and industrial inspections.
- Environmental Monitoring: Used in environmental sensors to filter specific wavelengths for accurate measurement of pollutants and other environmental factors.
7. SOT Strengths and Capabilities
Shape Optics Technologies Pte Ltd (SOT) has established itself as a leader in optical technology, specializing in precision filters that are tailored to meet the specific needs of its clients. With years of experience in the field, SOT offers extensive customization capabilities, high-quality manufacturing standards, and unparalleled customer support. Their products are designed for use in critical applications, ensuring exceptional durability and reliability.
8. Standard Products
| Model | Cut-on Wavelength (nm) | Transmittance | Wavelength Range | Optical Density (OD) |
| NH-LP470 | 470±5 | T≥90% | 480-1100 | OD≥3@350-460 |
| NH-LP480 | 480±5 | T≥90% | 490-1100 | OD≥3@350-470 |
| NH-LP490 | 490±5 | T≥90% | 500-1100 | OD≥3@350-480 |
| … | … | … | … | … |
(Further models available on request, customized to meet specific application needs.)
