Hemoglobin detection device (100) includes spectrum adjustable emitter detector cell (102), it is configured to emit or detection electromagnetic radiation spectrum selectively and periodically covers spectral modulation interval modulation frequency at different wavelengths, and provides function of the detector signal for indicating detected electromagnetic radiation as the time. The equipment further includes processing unit (116), is configured to receive detector signal and provides output signal, indicates the contribution of at least one frequency component, the modulating frequency of the second or higher even-order harmonic is consequently formed to detector signal. Hemoglobin detection device can be used for photoplethysmography application.
