532nm Bandpass Filter

  • BP532-1: Ultra-narrow 1nm FWHM for ultimate spectral precision in LiDAR and Raman spectroscopy
  • BP532-2: 2nm FWHM optimized for frequency-doubled Nd:YAG laser line cleanup
  • BP532-3: 3nm FWHM for ultra-precision laser applications requiring absolute spectral purity
  • BP532-10: 10nm FWHM with OD6 blocking, ideal for Raman spectroscopy and laser line isolation
  • BP532-15: 15nm FWHM for high-precision fluorescence microscopy and analytical systems
  • BP532-20: 20nm FWHM balancing spectral selectivity with good light collection efficiency
  • BP532-35: 35nm FWHM for fluorescence microscopy and GFP detection applications
  • BP532-50: Wide 50nm FWHM for machine vision and maximum light collection
  • US Patent Application 2005 0162648 -System and Method for Multiple Laser Flow Cytometry

    US Patent Application 2005/0162648 - System and Method for Multiple Laser Flow Cytometry

    Context: This patent application describes a flow cytometer, a device used to count and analyze microscopic particles (like cells) by suspending them in a stream of fluid and passing them through an electronic detection apparatus.

    Usage of Filter: The 532nm bandpass filter is placed specifically in front of a photodiode detector.

    Function: It is used to isolate the scattered light or fluorescence that matches the 532nm excitation source. When a particle passes through the 532nm laser beam, it scatters light. The filter ensures the detector only sees this specific wavelength, blocking ambient light or signals from other lasers (like red or blue lasers used simultaneously in the system).

    Result: The filter allows the system to accurately trigger a detection event. "When the photodiode with the 532 nm bandpass filter detects a response, the particle is [confirmed to be] in front of the 532 nm laser," allowing for precise timing and sequencing of data acquisition.

  • US Patent 145 08 DE112004002460 related - Nonlinear Optical Molecular Orientation

    US Patent 7,145,108 / DE112004002460 (related) - Nonlinear Optical Molecular Orientation

    Context: These patent documents often relate to measuring Second Harmonic Generation (SHG), a nonlinear optical process where two photons interact to form a new photon with twice the energy (half the wavelength).

    Usage of Filter: A 532nm bandpass filter is placed in front of a Photomultiplier Tube (PMT) detector.

    Function: In this setup, an infrared laser (1064nm) hits a sample. The sample generates a weak "second harmonic" signal at exactly half the wavelength—532nm. The bandpass filter is crucial here because it blocks the intense 1064nm pump laser light while allowing only the faint 532nm signal to pass to the detector.

    Result: It achieves a high Signal-to-Noise Ratio (SNR), enabling the detection of molecular orientation in materials like zeolites or biological tissues without blinding the sensitive PMT with the original infrared laser beam.

  • US Patent 11,175,232 - Standoff Ultra-Compact Micro-Raman Sensors

    Context: This patent, assigned to NASA, describes a compact Raman sensor designed for planetary exploration (e.g., lunar rovers) to identify unknown minerals and substances remotely ("standoff" detection) without needing to collect a sample physically.

    The Bandpass Filter is used as: A Laser Line Clean-Up Filter in the excitation path.

    In this optical setup, a 532nm pulsed laser is used to illuminate the target. The 532nm bandpass filter is placed immediately after the laser source but before the beam expander or the target.

    Its specific job is to transmit only the narrow 532nm laser line while blocking any unwanted "spectral noise," such as plasma glow or spontaneous emission (fluorescence) generated by the laser hardware itself.

    Achieving this result:

    High Signal Purity: By stripping away non-532nm wavelengths before they hit the sample, the filter prevents "false peaks" from appearing in the data.

    Improved Sensitivity: Since Raman signals are incredibly weak (1 photon in a million), even faint background noise from the laser source can drown them out. The bandpass filter ensures that any light detected at wavelengths other than 532nm is genuinely from the sample (Raman scattering), not leakage from the laser.

  • Light Sources for getting 532nm

    Why not use an LED to get 532nm?

    Standard green LEDs typically peak around 520–525 nm or 550–570 nm (lime/yellow-green).

    • The "Green Gap": It is physically difficult to manufacture high-efficiency semiconductor materials that emit exactly at 532 nm.
    • Spectral Width: Even if an LED is centered near 532 nm, its light is "blurry" (broadband), whereas a laser is a single, sharp frequency.

    Is there any direct diode creating 532nm light?

    The short answer is no. There is currently no commercially available semiconductor diode that generates 532 nm light directly.

    Why doesn't a direct 532 nm diode exist?

    Creating a direct semiconductor laser depends on the "bandgap" of the material used.

    • The Material Gap: Direct green diodes are typically made from Indium Gallium Nitride (InGaN). While engineers can "tune" this material to produce different colors, it becomes very inefficient as you move toward the longer green wavelengths.
    • The 520 nm Limit: Currently, the "sweet spot" for direct InGaN green diodes is around 515 nm to 525 nm. Pushing the chemistry to hit exactly 532 nm results in diodes that have very short lifespans or extremely low efficiency.

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