A holographic observation method includes: casting a light beam generated by driving a semiconductor laser light source with an electric current with an alternating-current component superimposed or a light beam having a predetermined spectral width and predetermined spectral intensity to have predetermined coherency to an observation object; forming a hologram by causing a light beam transmitted through or reflected by the observation object to interfere with a reference light beam; and obtaining information on the observation object by performing image processing on the hologram.

In a drive unit according to an embodiment of the present disclosure, in each of a plurality of current pulses, a rising crest value is the largest, and after the rising, the crest value is damped. Further, a rising crest value of a pulse of an n+1-th wave is smaller than a rising crest value of a pulse of an n-th wave. Furthermore, rising crest values of the current pulses of a second wave and waves after the second wave are determined by a mathematical function expressed as an electric potential change caused by ON-OFF of an RC time constant circuit that is single-end grounded. Moreover, in the mathematical function, a time constant at an OFF time is larger than a time constant at an ON time.

The laser projection display device (1) includes a laser beam source (5), a laser driver (4) driving the laser beam source, and an image processing unit (2) supplying a display image signal to the laser driver. The image processing unit applies a preliminary emission signal (53) to perform preliminary emission to an image signal (50) in a predetermined period (t0 to t1) immediately before a black pixel signal is switched to a signal except for the black pixel signal when the image signal has a black pixel duration. In particular, the preliminary emission process is performed when the laser beam source is operated in a dark image region while being reduced in maximum light intensity, and, as the preliminary emission signal, a signal (L0) corresponding to a light intensity which is 1/10 or less a maximum light intensity (La) in the dark image region.

A driver circuit 11 includes a plurality of cascode-connected NMOS transistors, a modulating signal V.sub.GN1 is applied to a gate terminal of a lowermost stage transistor T.sub.N1 located at a lowermost stage out of the NMOS transistors, and an upper stage bias potential V.sub.GN2 that is a sum of a minimum gate-source voltage V.sub.GN1min and a maximum drain-source voltage V.sub.DS1max of a transistor (T.sub.N1) located immediately below an upper stage transistor located at an upper stage above the lowermost stage transistor of the NMOS transistors is applied to the upper stage transistor T.sub.N2.

An LD driver circuit includes an adjustment circuit, to which a power supply voltage is applied, which receives an input signal through an input terminal, and which generates a shifted input signal shifted in voltage from the input signal by a predetermined shift amount and outputs the shifted input signal from an output terminal; and a transistor, in which a base receives the shifted input signal, in which a collector is electrically connected to an anode of an LD, in which an emitter is electrically connected to a cathode of the LD and a ground, and which varies an amount of a shunt current flowing the collector to the emitter in accordance with the shifted input signal. The adjustment circuit includes a comparator which compares a voltage in the collector and a threshold voltage, and increases or decreases the predetermined shift amount in accordance with an output of the comparator.

An analyzer includes a quantum cascade laser that converts a cyclic driving signal to laser light; an optical receiver that receives the laser light having passed through a sample and outputs a detected signal depending on intensity of the laser light; and a data calculation portion that outputs information representing absorption characteristics of the sample. The data calculation portion includes a delaying unit that produces a time-delayed waveform by applying a time delay to a reference driving signal; an adding unit that produces a symmetrical waveform by adding the time-delayed waveform and the detected signal; a time inversion unit that produces a time-inverted waveform by time-inverting the symmetrical waveform; and a subtracting unit that produces a waveform difference between the time-inverted waveform and the symmetrical waveform. The data calculation portion repeatedly calculates the waveform difference by changing the time delay until the waveform difference is minimized.

A speckle laser device based on low time coherence and low spatial coherence, and a preparation method therefor. The speckle laser device comprises a radio frequency modulator (1), a laser device (2), a diffracting optical element (3) and a focusing lens (4) that are coaxially and sequentially disposed on a same optical platform. The diffracting optical element (3) is located in the emergent direction of the laser device (2), the radio frequency modulator (1) modulates the laser device (2), and laser (001) modulated by the radio frequency modulator (1) enters the diffracting optical element (3). Laser beams emerging from the diffracting optical element (3) are zero-coherent speckle laser beams (002), the laser beams (002) enter the focusing lens (4), and the laser emerging from the focusing lens (4) forms a focused speckle laser (003). Speckle laser output beams are obtained by using a time coherence and spatial coherence reduction technology, and the problem of speckle production due to time coherence and spatial coherence is resolved.

A wavelength beam combining device includes: a light source unit comprising a plurality of laser light sources, each being configured to emit a laser beam with a predetermined wavelength width; a light condensing member configured to condense the laser beams emitted from the light source unit; a diffraction grating on which the laser beams condensed by the light condensing member are incident; a resonator mirror disposed in an optical path of a diffracted beam from the diffraction grating; and an output control unit configured to turn off, among the plurality of laser light sources, at least laser light sources located farthest from an optical axis of the light condensing member, to reduce an output of the wavelength beam combining device relative to an output of the wavelength beam combining device when all the plurality of laser light sources are turned on.

A semiconductor laser device includes a laser region including an active layer and configured to generate light, an amplification region including the active layer and configured to amplify the light, the amplification region being adjacent to the layer region, and an electrode provided to extend over the laser region and the amplification region.

A semiconductor laser driving circuit that ensures the satisfied extinction ratio, the accuracy of the light output, and enables the light output dynamically to change based on a modulation signal. The semiconductor laser driving circuit includes a semiconductor laser LD of which the laser light is modulated by the analog modulation signal v_MOD, the differential pair circuit having impedance elements 11, 12 and transistors Q1, Q2, a power source 13, a differential driver 22 that generates a differential voltage to switch on-and-off the transistors Q1, Q2 by an analog modulation signal, a threshold electric current generation element that generates the threshold electric current to flow the threshold that the semiconductor laser emits, a slope signal generation element 32 that generates a slope signal V_SLOPE by executing a level conversion by a predetermined slope coefficient relative to the analog modulation signal, and an adder 35 that adds a slope signal, which the slope generation element generates and the threshold electric current that the threshold electric current generation element and controls the electric current or the power source by the addition output.